From 2a6e9c5e8ae259d6f286437352bfff06c040c9e7 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 30 May 2021 19:28:26 -0400
Subject: [PATCH 001/117] Add readme for Enterprise ROM names.

---
 ROMImages/Enterprise/readme.txt | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 ROMImages/Enterprise/readme.txt

diff --git a/ROMImages/Enterprise/readme.txt b/ROMImages/Enterprise/readme.txt
new file mode 100644
index 000000000..2b4947e52
--- /dev/null
+++ b/ROMImages/Enterprise/readme.txt
@@ -0,0 +1,5 @@
+ROM files would ordinarily go here; the copyright status of these is uncertain so they have not been included in this repository.
+
+Expected files:
+
+exos.rom

From 61c127ed2e888f58d1bb7a238b29a92906fe386e Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 20:55:39 -0400
Subject: [PATCH 002/117] Adds Enterprise as a File -> New... machine.

And, similarly, exposes it for the route used by SDL.
---
 Analyser/Machines.hpp                         |   1 +
 Machines/Enterprise/Enterprise.cpp            |  35 ++++++
 Machines/Enterprise/Enterprise.hpp            |  27 +++++
 Machines/Utility/MachineForTarget.cpp         |   9 +-
 .../Clock Signal.xcodeproj/project.pbxproj    |  34 ++++++
 .../xcschemes/Clock Signal Kiosk.xcscheme     |  10 +-
 .../Machine/StaticAnalyser/CSStaticAnalyser.h |   7 ++
 .../StaticAnalyser/CSStaticAnalyser.mm        |  12 +++
 .../Base.lproj/MachinePicker.xib              | 100 +++++++++++-------
 .../MachinePicker/MachinePicker.swift         |  16 +--
 Storage/TargetPlatforms.hpp                   |  15 +--
 11 files changed, 207 insertions(+), 59 deletions(-)
 create mode 100644 Machines/Enterprise/Enterprise.cpp
 create mode 100644 Machines/Enterprise/Enterprise.hpp

diff --git a/Analyser/Machines.hpp b/Analyser/Machines.hpp
index 7159408f8..5c8fb6602 100644
--- a/Analyser/Machines.hpp
+++ b/Analyser/Machines.hpp
@@ -19,6 +19,7 @@ enum class Machine {
 	AtariST,
 	ColecoVision,
 	Electron,
+	Enterprise,
 	Macintosh,
 	MasterSystem,
 	MSX,
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
new file mode 100644
index 000000000..ce793368d
--- /dev/null
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -0,0 +1,35 @@
+//
+//  Enterprise.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 10/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#include "Enterprise.hpp"
+
+#include "../../Analyser/Static/Enterprise/Target.hpp"
+
+namespace Enterprise {
+
+class ConcreteMachine:
+	public Machine {
+	public:
+		ConcreteMachine(const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) {
+			(void)target;
+			(void)rom_fetcher;
+		}
+};
+
+}
+
+using namespace Enterprise;
+
+Machine *Machine::Enterprise(const Analyser::Static::Target *target, const ROMMachine::ROMFetcher &rom_fetcher) {
+	using Target = Analyser::Static::Enterprise::Target;
+	const Target *const enterprise_target = dynamic_cast<const Target *>(target);
+
+	return new Enterprise::ConcreteMachine(*enterprise_target, rom_fetcher);
+}
+
+Machine::~Machine() {}
diff --git a/Machines/Enterprise/Enterprise.hpp b/Machines/Enterprise/Enterprise.hpp
new file mode 100644
index 000000000..3a42a70f5
--- /dev/null
+++ b/Machines/Enterprise/Enterprise.hpp
@@ -0,0 +1,27 @@
+//
+//  Enterprise.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 10/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#ifndef Enterprise_hpp
+#define Enterprise_hpp
+
+#include "../../Analyser/Static/StaticAnalyser.hpp"
+#include "../ROMMachine.hpp"
+
+namespace Enterprise {
+
+class Machine {
+	public:
+		virtual ~Machine();
+
+		static Machine *Enterprise(const Analyser::Static::Target *target, const ROMMachine::ROMFetcher &rom_fetcher);
+
+};
+
+};
+
+#endif /* Enterprise_hpp */
diff --git a/Machines/Utility/MachineForTarget.cpp b/Machines/Utility/MachineForTarget.cpp
index 0a576e867..0c1e92500 100644
--- a/Machines/Utility/MachineForTarget.cpp
+++ b/Machines/Utility/MachineForTarget.cpp
@@ -20,6 +20,7 @@
 #include "../ColecoVision/ColecoVision.hpp"
 #include "../Commodore/Vic-20/Vic20.hpp"
 #include "../Electron/Electron.hpp"
+#include "../Enterprise/Enterprise.hpp"
 #include "../MasterSystem/MasterSystem.hpp"
 #include "../MSX/MSX.hpp"
 #include "../Oric/Oric.hpp"
@@ -34,6 +35,7 @@
 #include "../../Analyser/Static/Atari2600/Target.hpp"
 #include "../../Analyser/Static/AtariST/Target.hpp"
 #include "../../Analyser/Static/Commodore/Target.hpp"
+#include "../../Analyser/Static/Enterprise/Target.hpp"
 #include "../../Analyser/Static/Macintosh/Target.hpp"
 #include "../../Analyser/Static/MSX/Target.hpp"
 #include "../../Analyser/Static/Oric/Target.hpp"
@@ -49,7 +51,7 @@ Machine::DynamicMachine *Machine::MachineForTarget(const Analyser::Static::Targe
 
 	Machine::DynamicMachine *machine = nullptr;
 	try {
-#define BindD(name, m)	case Analyser::Machine::m: machine = new Machine::TypedDynamicMachine<name::Machine>(name::Machine::m(target, rom_fetcher));	break;
+#define BindD(name, m)	case Analyser::Machine::m: machine = new Machine::TypedDynamicMachine<::name::Machine>(name::Machine::m(target, rom_fetcher));	break;
 #define Bind(m)	BindD(m, m)
 		switch(target->machine) {
 			Bind(AmstradCPC)
@@ -61,6 +63,7 @@ Machine::DynamicMachine *Machine::MachineForTarget(const Analyser::Static::Targe
 			BindD(Coleco::Vision, ColecoVision)
 			BindD(Commodore::Vic20, Vic20)
 			Bind(Electron)
+			Bind(Enterprise)
 			Bind(MSX)
 			Bind(Oric)
 			BindD(Sega::MasterSystem, MasterSystem)
@@ -127,6 +130,7 @@ std::string Machine::ShortNameForTargetMachine(const Analyser::Machine machine)
 		case Analyser::Machine::AtariST:		return "AtariST";
 		case Analyser::Machine::ColecoVision:	return "ColecoVision";
 		case Analyser::Machine::Electron:		return "Electron";
+		case Analyser::Machine::Enterprise:		return "Enterprise";
 		case Analyser::Machine::Macintosh:		return "Macintosh";
 		case Analyser::Machine::MasterSystem:	return "MasterSystem";
 		case Analyser::Machine::MSX:			return "MSX";
@@ -148,6 +152,7 @@ std::string Machine::LongNameForTargetMachine(Analyser::Machine machine) {
 		case Analyser::Machine::AtariST:		return "Atari ST";
 		case Analyser::Machine::ColecoVision:	return "ColecoVision";
 		case Analyser::Machine::Electron:		return "Acorn Electron";
+		case Analyser::Machine::Enterprise:		return "Enterprise";
 		case Analyser::Machine::Macintosh:		return "Apple Macintosh";
 		case Analyser::Machine::MasterSystem:	return "Sega Master System";
 		case Analyser::Machine::MSX:			return "MSX";
@@ -177,6 +182,7 @@ std::vector<std::string> Machine::AllMachines(Type type, bool long_names) {
 		AddName(AppleIIgs);
 		AddName(AtariST);
 		AddName(Electron);
+		AddName(Enterprise);
 		AddName(Macintosh);
 		AddName(MSX);
 		AddName(Oric);
@@ -226,6 +232,7 @@ std::map<std::string, std::unique_ptr<Analyser::Static::Target>> Machine::Target
 	Add(AppleIIgs);
 	Add(AtariST);
 	AddMapped(Electron, Acorn);
+	Add(Enterprise);
 	Add(Macintosh);
 	Add(MSX);
 	Add(Oric);
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index 5bdace657..6ef07aa80 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -17,6 +17,10 @@
 		4B051C93266D9D6900CA44E8 /* ROMImages in Resources */ = {isa = PBXBuildFile; fileRef = 4BC9DF441D044FCA00F44158 /* ROMImages */; };
 		4B051C95266EF50200CA44E8 /* AppleIIOptionsPanel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B051C94266EF50200CA44E8 /* AppleIIOptionsPanel.swift */; };
 		4B051C97266EF5F600CA44E8 /* CSAppleII.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4B051C96266EF5F600CA44E8 /* CSAppleII.mm */; };
+		4B051CA22676F52200CA44E8 /* Enterprise.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CA12676F52200CA44E8 /* Enterprise.cpp */; };
+		4B051CA32676F52200CA44E8 /* Enterprise.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CA12676F52200CA44E8 /* Enterprise.cpp */; };
+		4B051CA826781D6500CA44E8 /* StaticAnalyser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CA726781D6500CA44E8 /* StaticAnalyser.cpp */; };
+		4B051CA926781D6500CA44E8 /* StaticAnalyser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CA726781D6500CA44E8 /* StaticAnalyser.cpp */; };
 		4B05401E219D1618001BF69C /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B05401D219D1618001BF69C /* ScanTarget.cpp */; };
 		4B05401F219D1618001BF69C /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B05401D219D1618001BF69C /* ScanTarget.cpp */; };
 		4B055A7A1FAE78A00060FFFF /* SDL2.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 4B055A771FAE78210060FFFF /* SDL2.framework */; };
@@ -1028,6 +1032,11 @@
 		4B051C94266EF50200CA44E8 /* AppleIIOptionsPanel.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AppleIIOptionsPanel.swift; sourceTree = "<group>"; };
 		4B051C96266EF5F600CA44E8 /* CSAppleII.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = CSAppleII.mm; sourceTree = "<group>"; };
 		4B051C98266EF60500CA44E8 /* CSAppleII.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = CSAppleII.h; sourceTree = "<group>"; };
+		4B051CA02676F52200CA44E8 /* Enterprise.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = Enterprise.hpp; sourceTree = "<group>"; };
+		4B051CA12676F52200CA44E8 /* Enterprise.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = Enterprise.cpp; sourceTree = "<group>"; };
+		4B051CA526781D6500CA44E8 /* StaticAnalyser.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = StaticAnalyser.hpp; sourceTree = "<group>"; };
+		4B051CA626781D6500CA44E8 /* Target.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = Target.hpp; sourceTree = "<group>"; };
+		4B051CA726781D6500CA44E8 /* StaticAnalyser.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = StaticAnalyser.cpp; sourceTree = "<group>"; };
 		4B05401D219D1618001BF69C /* ScanTarget.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = ScanTarget.cpp; sourceTree = "<group>"; };
 		4B055A6A1FAE763F0060FFFF /* Clock Signal Kiosk */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = "Clock Signal Kiosk"; sourceTree = BUILT_PRODUCTS_DIR; };
 		4B055A771FAE78210060FFFF /* SDL2.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = SDL2.framework; path = ../../../../Library/Frameworks/SDL2.framework; sourceTree = SOURCE_ROOT; };
@@ -2090,6 +2099,25 @@
 /* End PBXFrameworksBuildPhase section */
 
 /* Begin PBXGroup section */
+		4B051C9F2676F52200CA44E8 /* Enterprise */ = {
+			isa = PBXGroup;
+			children = (
+				4B051CA02676F52200CA44E8 /* Enterprise.hpp */,
+				4B051CA12676F52200CA44E8 /* Enterprise.cpp */,
+			);
+			path = Enterprise;
+			sourceTree = "<group>";
+		};
+		4B051CA426781D6500CA44E8 /* Enterprise */ = {
+			isa = PBXGroup;
+			children = (
+				4B051CA726781D6500CA44E8 /* StaticAnalyser.cpp */,
+				4B051CA526781D6500CA44E8 /* StaticAnalyser.hpp */,
+				4B051CA626781D6500CA44E8 /* Target.hpp */,
+			);
+			path = Enterprise;
+			sourceTree = "<group>";
+		};
 		4B055A761FAE78210060FFFF /* Frameworks */ = {
 			isa = PBXGroup;
 			children = (
@@ -3185,6 +3213,7 @@
 				4B8944FB201967B4007DE474 /* Commodore */,
 				4B894507201967B4007DE474 /* Disassembler */,
 				4BD67DC8209BE4D600AB2146 /* DiskII */,
+				4B051CA426781D6500CA44E8 /* Enterprise */,
 				4BB4BFB622A4372E0069048D /* Macintosh */,
 				4B89450F201967B4007DE474 /* MSX */,
 				4B8944F6201967B4007DE474 /* Oric */,
@@ -4075,6 +4104,7 @@
 				4B7A90E22041097C008514A2 /* ColecoVision */,
 				4B4DC81D1D2C2425003C5BF8 /* Commodore */,
 				4B2E2D9E1C3A070900138695 /* Electron */,
+				4B051C9F2676F52200CA44E8 /* Enterprise */,
 				4B7F188B2154825D00388727 /* MasterSystem */,
 				4B79A4FC1FC8FF9800EEDAD5 /* MSX */,
 				4BCF1FA51DADC3E10039D2E7 /* Oric */,
@@ -5177,6 +5207,7 @@
 				4B055AB41FAE860F0060FFFF /* OricTAP.cpp in Sources */,
 				4B055AB71FAE860F0060FFFF /* TZX.cpp in Sources */,
 				4B2BF19123DCC6A200C3AD60 /* BD500.cpp in Sources */,
+				4B051CA926781D6500CA44E8 /* StaticAnalyser.cpp in Sources */,
 				4B055ADA1FAE9B460060FFFF /* 1770.cpp in Sources */,
 				4B80CD77256CA16600176FCC /* 2MG.cpp in Sources */,
 				4B0F1BE62602FF9D00B85C66 /* ZX8081.cpp in Sources */,
@@ -5186,6 +5217,7 @@
 				4B055AB61FAE860F0060FFFF /* TapeUEF.cpp in Sources */,
 				4B055A9D1FAE85DA0060FFFF /* D64.cpp in Sources */,
 				4B0ACC2B23775819008902D0 /* Video.cpp in Sources */,
+				4B051CA32676F52200CA44E8 /* Enterprise.cpp in Sources */,
 				4B055ABB1FAE86170060FFFF /* Oric.cpp in Sources */,
 				4B12C0EE1FCFAD1A005BFD93 /* Keyboard.cpp in Sources */,
 				4BCD634A22D6756400F567F1 /* MacintoshDoubleDensityDrive.cpp in Sources */,
@@ -5492,6 +5524,7 @@
 				4B12C0ED1FCFA98D005BFD93 /* Keyboard.cpp in Sources */,
 				4BA0F68E1EEA0E8400E9489E /* ZX8081.cpp in Sources */,
 				4BD468F71D8DF41D0084958B /* 1770.cpp in Sources */,
+				4B051CA22676F52200CA44E8 /* Enterprise.cpp in Sources */,
 				4B7F1897215486A200388727 /* StaticAnalyser.cpp in Sources */,
 				4B47F6C5241C87A100ED06F7 /* Struct.cpp in Sources */,
 				4B5FADBA1DE3151600AEC565 /* FileHolder.cpp in Sources */,
@@ -5505,6 +5538,7 @@
 				4B74CF812312FA9C00500CE8 /* HFV.cpp in Sources */,
 				4B17B58B20A8A9D9007CCA8F /* StringSerialiser.cpp in Sources */,
 				4B2E2D9D1C3A070400138695 /* Electron.cpp in Sources */,
+				4B051CA826781D6500CA44E8 /* StaticAnalyser.cpp in Sources */,
 				4B3940E71DA83C8300427841 /* AsyncTaskQueue.cpp in Sources */,
 				4B0E04FA1FC9FA3100F43484 /* 9918.cpp in Sources */,
 				4B69FB3D1C4D908A00B5F0AA /* Tape.cpp in Sources */,
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal Kiosk.xcscheme b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal Kiosk.xcscheme
index 2b77bafce..d3942a20a 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal Kiosk.xcscheme	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal Kiosk.xcscheme	
@@ -85,8 +85,8 @@
             isEnabled = "YES">
          </CommandLineArgument>
          <CommandLineArgument
-            argument = "--new=amstradcpc"
-            isEnabled = "NO">
+            argument = "--new=enterprise"
+            isEnabled = "YES">
          </CommandLineArgument>
          <CommandLineArgument
             argument = "&quot;/Users/thomasharte/Library/Mobile Documents/com~apple~CloudDocs/Desktop/Soft/ColecoVision/Galaxian (1983)(Atari).col&quot;"
@@ -126,15 +126,15 @@
          </CommandLineArgument>
          <CommandLineArgument
             argument = "--model=mac512k"
-            isEnabled = "YES">
+            isEnabled = "NO">
          </CommandLineArgument>
          <CommandLineArgument
             argument = "--new=macintosh"
-            isEnabled = "YES">
+            isEnabled = "NO">
          </CommandLineArgument>
          <CommandLineArgument
             argument = "--use-square-pixels"
-            isEnabled = "YES">
+            isEnabled = "NO">
          </CommandLineArgument>
       </CommandLineArguments>
    </LaunchAction>
diff --git a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h
index e82adb720..d064f48e8 100644
--- a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h	
+++ b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h	
@@ -41,6 +41,12 @@ typedef NS_ENUM(NSInteger, CSMachineCPCModel) {
 	CSMachineCPCModel6128
 };
 
+typedef NS_ENUM(NSInteger, CSMachineEnterpriseModel) {
+	CSMachineEnterpriseModel64,
+	CSMachineEnterpriseModel128,
+	CSMachineEnterpriseModel256,
+};
+
 typedef NS_ENUM(NSInteger, CSMachineMacintoshModel) {
 	CSMachineMacintoshModel128k,
 	CSMachineMacintoshModel512k,
@@ -96,6 +102,7 @@ typedef int Kilobytes;
 - (instancetype)initWithAppleIIgsModel:(CSMachineAppleIIgsModel)model memorySize:(Kilobytes)memorySize;
 - (instancetype)initWithAtariSTModel:(CSMachineAtariSTModel)model;
 - (instancetype)initWithElectronDFS:(BOOL)dfs adfs:(BOOL)adfs ap6:(BOOL)ap6 sidewaysRAM:(BOOL)sidewaysRAM;
+- (instancetype)initWithEnterpriseModel:(CSMachineEnterpriseModel)model;
 - (instancetype)initWithMacintoshModel:(CSMachineMacintoshModel)model;
 - (instancetype)initWithMSXRegion:(CSMachineMSXRegion)region hasDiskDrive:(BOOL)hasDiskDrive;
 - (instancetype)initWithOricModel:(CSMachineOricModel)model diskInterface:(CSMachineOricDiskInterface)diskInterface;
diff --git a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm
index acc8dd852..5a7a4032c 100644
--- a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm	
+++ b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm	
@@ -19,6 +19,7 @@
 #include "../../../../../Analyser/Static/AppleIIgs/Target.hpp"
 #include "../../../../../Analyser/Static/AtariST/Target.hpp"
 #include "../../../../../Analyser/Static/Commodore/Target.hpp"
+#include "../../../../../Analyser/Static/Enterprise/Target.hpp"
 #include "../../../../../Analyser/Static/Macintosh/Target.hpp"
 #include "../../../../../Analyser/Static/MSX/Target.hpp"
 #include "../../../../../Analyser/Static/Oric/Target.hpp"
@@ -130,6 +131,17 @@
 	return self;
 }
 
+- (instancetype)initWithEnterpriseModel:(CSMachineEnterpriseModel)model {
+	self = [super init];
+	if(self) {
+		using Target = Analyser::Static::Enterprise::Target;
+		auto target = std::make_unique<Target>();
+		// TODO: apply model.
+		_targets.push_back(std::move(target));
+	}
+	return self;
+}
+
 - (instancetype)initWithMacintoshModel:(CSMachineMacintoshModel)model {
 	self = [super init];
 	if(self) {
diff --git a/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib b/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib
index cc68c2170..75127f3c4 100644
--- a/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib	
+++ b/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib	
@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="17701" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none" useAutolayout="YES" customObjectInstantitationMethod="direct">
+<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="18122" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none" useAutolayout="YES" customObjectInstantitationMethod="direct">
     <dependencies>
         <deployment identifier="macosx"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.CocoaPlugin" version="17701"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.CocoaPlugin" version="18122"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
     <objects>
@@ -17,10 +17,10 @@
         <window title="Window" allowsToolTipsWhenApplicationIsInactive="NO" autorecalculatesKeyViewLoop="NO" releasedWhenClosed="NO" visibleAtLaunch="NO" animationBehavior="default" titleVisibility="hidden" id="QvC-M9-y7g">
             <windowStyleMask key="styleMask" titled="YES" documentModal="YES"/>
             <windowPositionMask key="initialPositionMask" leftStrut="YES" rightStrut="YES" topStrut="YES" bottomStrut="YES"/>
-            <rect key="contentRect" x="196" y="240" width="590" height="316"/>
+            <rect key="contentRect" x="196" y="240" width="590" height="353"/>
             <rect key="screenRect" x="0.0" y="0.0" width="2560" height="1440"/>
             <view key="contentView" wantsLayer="YES" id="EiT-Mj-1SZ">
-                <rect key="frame" x="0.0" y="0.0" width="590" height="316"/>
+                <rect key="frame" x="0.0" y="0.0" width="590" height="353"/>
                 <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                 <subviews>
                     <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="hKn-1l-OSN">
@@ -59,7 +59,7 @@ Gw
                         </textFieldCell>
                     </textField>
                     <tabView type="noTabsBezelBorder" translatesAutoresizingMaskIntoConstraints="NO" id="VUb-QG-x7c">
-                        <rect key="frame" x="154" y="56" width="420" height="206"/>
+                        <rect key="frame" x="154" y="56" width="420" height="243"/>
                         <font key="font" metaFont="system"/>
                         <tabViewItems>
                             <tabViewItem label="Apple II" identifier="appleii" id="P59-QG-LOa">
@@ -254,32 +254,32 @@ Gw
                             </tabViewItem>
                             <tabViewItem label="Electron" identifier="electron" id="muc-z9-Vqc">
                                 <view key="view" id="SRc-2D-95G">
-                                    <rect key="frame" x="10" y="7" width="400" height="76"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="JqM-IK-FMP">
-                                            <rect key="frame" x="18" y="56" width="168" height="18"/>
+                                            <rect key="frame" x="18" y="166" width="168" height="18"/>
                                             <buttonCell key="cell" type="check" title="With Disk Filing System" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="tpW-5C-xKp">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
                                             </buttonCell>
                                         </button>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="945-wU-JOH">
-                                            <rect key="frame" x="18" y="34" width="232" height="18"/>
+                                            <rect key="frame" x="18" y="144" width="232" height="18"/>
                                             <buttonCell key="cell" type="check" title="With Advanced Disk Filing System" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="S0c-Jg-7Pu">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
                                             </buttonCell>
                                         </button>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="cG2-Ph-S3Z">
-                                            <rect key="frame" x="18" y="12" width="231" height="18"/>
+                                            <rect key="frame" x="18" y="122" width="231" height="18"/>
                                             <buttonCell key="cell" type="check" title="With Advanced Plus 6 Utility ROM" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="yjF-XS-zx6">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
                                             </buttonCell>
                                         </button>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="lzo-8g-o4S">
-                                            <rect key="frame" x="18" y="-10" width="284" height="18"/>
+                                            <rect key="frame" x="18" y="100" width="284" height="18"/>
                                             <buttonCell key="cell" type="check" title="Fill unused ROM banks with sideways RAM" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="JEz-eK-uWp">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
@@ -303,13 +303,33 @@ Gw
                                     </constraints>
                                 </view>
                             </tabViewItem>
+                            <tabViewItem label="Enterprise" identifier="enterprise" id="zhO-EO-wUe">
+                                <view key="view" id="1cs-PX-RAH">
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
+                                    <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                                    <subviews>
+                                        <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="Bkl-NN-Hml">
+                                            <rect key="frame" x="18" y="203" width="168" height="18"/>
+                                            <buttonCell key="cell" type="check" title="With Disk Filing System" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="yKr-e9-cKA">
+                                                <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
+                                                <font key="font" metaFont="system"/>
+                                            </buttonCell>
+                                        </button>
+                                    </subviews>
+                                    <constraints>
+                                        <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="Bkl-NN-Hml" secondAttribute="trailing" constant="20" symbolic="YES" id="0JK-jh-Dyl"/>
+                                        <constraint firstItem="Bkl-NN-Hml" firstAttribute="top" secondItem="1cs-PX-RAH" secondAttribute="top" constant="3" id="P2d-9U-kdR"/>
+                                        <constraint firstItem="Bkl-NN-Hml" firstAttribute="leading" secondItem="1cs-PX-RAH" secondAttribute="leading" constant="20" symbolic="YES" id="tjU-md-m2j"/>
+                                    </constraints>
+                                </view>
+                            </tabViewItem>
                             <tabViewItem label="Macintosh" identifier="mac" id="lmR-z3-xSm">
                                 <view key="view" id="7Yf-vi-Q0W">
-                                    <rect key="frame" x="10" y="7" width="400" height="76"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ZOY-4E-Cfl">
-                                            <rect key="frame" x="18" y="53" width="46" height="16"/>
+                                            <rect key="frame" x="18" y="163" width="46" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Model:" id="h9r-i6-66j">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -317,7 +337,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="xa6-NA-JY5">
-                                            <rect key="frame" x="67" y="47" width="75" height="25"/>
+                                            <rect key="frame" x="67" y="157" width="75" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Plus" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="3" imageScaling="axesIndependently" inset="2" selectedItem="R6T-hg-rOF" id="1Kb-Q2-BGM">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -344,18 +364,18 @@ Gw
                             </tabViewItem>
                             <tabViewItem label="MSX" identifier="msx" id="6SR-DY-zdI">
                                 <view key="view" id="mWD-An-tR7">
-                                    <rect key="frame" x="10" y="7" width="400" height="76"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="8xT-Pr-8SE">
-                                            <rect key="frame" x="18" y="26" width="128" height="18"/>
+                                            <rect key="frame" x="18" y="136" width="128" height="18"/>
                                             <buttonCell key="cell" type="check" title="Attach disk drive" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="CB3-nA-VTM">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
                                             </buttonCell>
                                         </button>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="LG6-mP-SeG">
-                                            <rect key="frame" x="71" y="47" width="146" height="25"/>
+                                            <rect key="frame" x="71" y="157" width="146" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="European (PAL)" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="xAh-Ch-tby" id="yR4-yv-Lvu">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -369,7 +389,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ZaD-7v-rMS">
-                                            <rect key="frame" x="18" y="53" width="50" height="16"/>
+                                            <rect key="frame" x="18" y="163" width="50" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Region:" id="x4m-eh-Nif">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -392,11 +412,11 @@ Gw
                             </tabViewItem>
                             <tabViewItem label="Oric" identifier="oric" id="NSx-DC-p4M">
                                 <view key="view" id="sOR-e0-8iZ">
-                                    <rect key="frame" x="10" y="7" width="400" height="76"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="0ct-tf-uRH">
-                                            <rect key="frame" x="18" y="53" width="46" height="16"/>
+                                            <rect key="frame" x="18" y="163" width="46" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Model:" id="Xm1-7x-YVl">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -404,7 +424,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ENP-hI-BVZ">
-                                            <rect key="frame" x="67" y="47" width="107" height="25"/>
+                                            <rect key="frame" x="67" y="157" width="107" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Oric-1" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="jGN-1a-biF" id="Jll-EJ-cMr">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -418,7 +438,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="fYL-p6-wyn">
-                                            <rect key="frame" x="113" y="17" width="130" height="25"/>
+                                            <rect key="frame" x="113" y="127" width="130" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="None" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="XhK-Jh-oTW" id="aYb-m1-H9X">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -434,7 +454,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="okM-ZI-NbF">
-                                            <rect key="frame" x="18" y="23" width="92" height="16"/>
+                                            <rect key="frame" x="18" y="133" width="92" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Disk interface:" id="SFK-hS-tFC">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -459,11 +479,11 @@ Gw
                             </tabViewItem>
                             <tabViewItem label="Vic-20" identifier="vic20" id="cyO-PU-hSU">
                                 <view key="view" id="fLI-XB-QCr">
-                                    <rect key="frame" x="10" y="7" width="400" height="76"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ueK-gq-gaF">
-                                            <rect key="frame" x="71" y="47" width="146" height="25"/>
+                                            <rect key="frame" x="71" y="157" width="146" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="European (PAL)" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="45i-0n-gau" id="yi7-eo-I0q">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -479,7 +499,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="2eV-Us-eEv">
-                                            <rect key="frame" x="108" y="17" width="116" height="25"/>
+                                            <rect key="frame" x="108" y="127" width="116" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Unexpanded" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="fOl-8Q-fsA" id="rH0-7T-pJE">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -493,7 +513,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="MTh-9p-FqC">
-                                            <rect key="frame" x="18" y="53" width="50" height="16"/>
+                                            <rect key="frame" x="18" y="163" width="50" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Region:" id="F3g-Ya-ypU">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -501,7 +521,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="gRS-DK-rIy">
-                                            <rect key="frame" x="18" y="23" width="87" height="16"/>
+                                            <rect key="frame" x="18" y="133" width="87" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Memory Size:" id="a4I-vG-yCp">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -509,7 +529,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="Lrf-gL-6EI">
-                                            <rect key="frame" x="18" y="-4" width="177" height="18"/>
+                                            <rect key="frame" x="18" y="106" width="177" height="18"/>
                                             <buttonCell key="cell" type="check" title="Attach C-1540 disk drive" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="tsq-YD-xw8">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
@@ -536,11 +556,11 @@ Gw
                             </tabViewItem>
                             <tabViewItem label="ZX80" identifier="zx80" id="tMH-kF-GUz">
                                 <view key="view" id="8hL-Vn-Hg0">
-                                    <rect key="frame" x="10" y="7" width="400" height="76"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="I1a-Eu-5UB">
-                                            <rect key="frame" x="108" y="47" width="116" height="25"/>
+                                            <rect key="frame" x="108" y="157" width="116" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Unexpanded" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="4Sa-jR-xOd" id="B8M-do-Yod">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -554,7 +574,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="NCX-4e-lSu">
-                                            <rect key="frame" x="18" y="53" width="87" height="16"/>
+                                            <rect key="frame" x="18" y="163" width="87" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Memory Size:" id="e6x-TE-OC5">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -562,7 +582,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ReP-bV-Thu">
-                                            <rect key="frame" x="18" y="26" width="118" height="18"/>
+                                            <rect key="frame" x="18" y="136" width="118" height="18"/>
                                             <buttonCell key="cell" type="check" title="Use ZX81 ROM" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="VQH-nv-Pfm">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
@@ -627,16 +647,16 @@ Gw
                                     <subviews>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="gFZ-d4-WFv">
                                             <rect key="frame" x="67" y="157" width="76" height="25"/>
-                                            <popUpButtonCell key="cell" type="push" title="16kb" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" borderStyle="borderAndBezel" tag="16" imageScaling="axesIndependently" inset="2" selectedItem="Fo7-NL-Kv5" id="tYs-sA-oek">
+                                            <popUpButtonCell key="cell" type="push" title="16kb" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="16" imageScaling="axesIndependently" inset="2" selectedItem="Fo7-NL-Kv5" id="tYs-sA-oek">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
                                                 <menu key="menu" id="8lt-dk-zPr">
                                                     <items>
-                                                        <menuItem title="16kb" tag="16" id="Fo7-NL-Kv5"/>
+                                                        <menuItem title="16kb" state="on" tag="16" id="Fo7-NL-Kv5"/>
                                                         <menuItem title="48kb" tag="48" id="xks-Rv-Umd"/>
                                                         <menuItem title="128kb" tag="128" id="w8h-lY-JLX"/>
                                                         <menuItem title="+2" tag="2" id="Vvu-ua-pjg"/>
-                                                        <menuItem title="+2a" state="on" tag="21" id="bFk-nC-Txe"/>
+                                                        <menuItem title="+2a" tag="21" id="bFk-nC-Txe"/>
                                                         <menuItem title="+3" tag="3" id="jwx-fZ-vXp"/>
                                                     </items>
                                                 </menu>
@@ -664,14 +684,14 @@ Gw
                         </tabViewItems>
                     </tabView>
                     <scrollView borderType="line" autohidesScrollers="YES" horizontalLineScroll="24" horizontalPageScroll="10" verticalLineScroll="24" verticalPageScroll="10" hasHorizontalScroller="NO" usesPredominantAxisScrolling="NO" id="z5Q-Bs-hJj">
-                        <rect key="frame" x="20" y="60" width="130" height="201"/>
+                        <rect key="frame" x="20" y="60" width="130" height="238"/>
                         <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" heightSizable="YES"/>
                         <clipView key="contentView" id="O8s-Vw-9yQ">
-                            <rect key="frame" x="1" y="1" width="128" height="199"/>
+                            <rect key="frame" x="1" y="1" width="128" height="236"/>
                             <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                             <subviews>
                                 <tableView verticalHuggingPriority="750" allowsExpansionToolTips="YES" columnAutoresizingStyle="none" columnReordering="NO" columnResizing="NO" multipleSelection="NO" emptySelection="NO" autosaveColumns="NO" typeSelect="NO" rowHeight="24" id="3go-Eb-GOy">
-                                    <rect key="frame" x="0.0" y="0.0" width="128" height="199"/>
+                                    <rect key="frame" x="0.0" y="0.0" width="128" height="236"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <size key="intercellSpacing" width="17" height="0.0"/>
                                     <color key="backgroundColor" name="controlBackgroundColor" catalog="System" colorSpace="catalog"/>
@@ -708,7 +728,7 @@ Gw
                         </scroller>
                     </scrollView>
                     <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="VAc-6N-O7q">
-                        <rect key="frame" x="18" y="269" width="554" height="27"/>
+                        <rect key="frame" x="18" y="306" width="554" height="27"/>
                         <textFieldCell key="cell" lineBreakMode="clipping" title="Choose a machine" id="32m-Vs-dPO">
                             <font key="font" textStyle="title2" name=".SFNS-Regular"/>
                             <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -737,7 +757,7 @@ Gw
                     <constraint firstItem="9YM-5x-pc0" firstAttribute="top" secondItem="z5Q-Bs-hJj" secondAttribute="bottom" constant="14" id="suf-rn-Bmy"/>
                 </constraints>
             </view>
-            <point key="canvasLocation" x="-1" y="88"/>
+            <point key="canvasLocation" x="-1" y="106.5"/>
         </window>
         <customObject id="192-Eb-Rpg" customClass="MachinePicker" customModule="Clock_Signal" customModuleProvider="target">
             <connections>
diff --git a/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift b/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift
index 3445c27da..24ccd2b9a 100644
--- a/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift	
+++ b/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift	
@@ -205,12 +205,6 @@ class MachinePicker: NSObject, NSTableViewDataSource, NSTableViewDelegate {
 		storeOptions()
 
 		switch machineSelector.selectedTabViewItem!.identifier as! String {
-			case "electron":
-				return CSStaticAnalyser(
-					electronDFS: electronDFSButton.state == .on,
-					adfs: electronADFSButton.state == .on,
-					ap6: electronAP6Button.state == .on,
-					sidewaysRAM: electronSidewaysRAMButton.state == .on)
 
 			case "appleii":
 				var model: CSMachineAppleIIModel = .appleII
@@ -255,6 +249,16 @@ class MachinePicker: NSObject, NSTableViewDataSource, NSTableViewDelegate {
 					default:	return CSStaticAnalyser(amstradCPCModel: .model6128)
 				}
 
+			case "electron":
+				return CSStaticAnalyser(
+					electronDFS: electronDFSButton.state == .on,
+					adfs: electronADFSButton.state == .on,
+					ap6: electronAP6Button.state == .on,
+					sidewaysRAM: electronSidewaysRAMButton.state == .on)
+
+			case "enterprise":
+				return CSStaticAnalyser(enterpriseModel: .model64)
+
 			case "mac":
 				switch macintoshModelTypeButton.selectedItem!.tag {
 					case 0:		return CSStaticAnalyser(macintoshModel: .model128k)
diff --git a/Storage/TargetPlatforms.hpp b/Storage/TargetPlatforms.hpp
index 60cbba1e3..c11ebfc39 100644
--- a/Storage/TargetPlatforms.hpp
+++ b/Storage/TargetPlatforms.hpp
@@ -29,13 +29,14 @@ enum Type: IntType {
 	Coleco			=	1 << 10,
 	Commodore		=	1 << 11,
 	DiskII			=	1 << 12,
-	Sega			=	1 << 13,
-	Macintosh		=	1 << 14,
-	MSX				=	1 << 15,
-	Oric			=	1 << 16,
-	ZX80			=	1 << 17,
-	ZX81			=	1 << 18,
-	ZXSpectrum		=	1 << 19,
+	Enterprise		=	1 << 13,
+	Sega			=	1 << 14,
+	Macintosh		=	1 << 15,
+	MSX				=	1 << 16,
+	Oric			=	1 << 17,
+	ZX80			=	1 << 18,
+	ZX81			=	1 << 19,
+	ZXSpectrum		=	1 << 20,
 
 	Acorn			=	AcornAtom | AcornElectron | BBCMaster | BBCModelA | BBCModelB,
 	ZX8081			=	ZX80 | ZX81,

From 5f7b3ae313ef5d0e1c259d1a483cf05b5a2c06c6 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 21:02:40 -0400
Subject: [PATCH 003/117] Adds bare minimum to get a non-functional machine.

---
 Machines/Enterprise/Enterprise.cpp | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index ce793368d..102cbea31 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -8,17 +8,39 @@
 
 #include "Enterprise.hpp"
 
+#include "../MachineTypes.hpp"
+
 #include "../../Analyser/Static/Enterprise/Target.hpp"
 
 namespace Enterprise {
 
 class ConcreteMachine:
-	public Machine {
+	public Machine,
+	public MachineTypes::ScanProducer,
+	public MachineTypes::TimedMachine {
 	public:
 		ConcreteMachine(const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) {
+			// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
+			set_clock_rate(4'000'000);
+
 			(void)target;
 			(void)rom_fetcher;
 		}
+
+	private:
+		// MARK: - ScanProducer
+		void set_scan_target(Outputs::Display::ScanTarget *scan_target) override {
+			(void)scan_target;
+		}
+
+		Outputs::Display::ScanStatus get_scaled_scan_status() const override {
+			return Outputs::Display::ScanStatus();
+		}
+
+		// MARK: - TimedMachine
+		void run_for(const Cycles cycles) override {
+			(void)cycles;
+		}
 };
 
 }

From 26b019a4d490aa2e0f6dd64180ccc86b251e7abc Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 21:02:55 -0400
Subject: [PATCH 004/117] Removes assumption that all machines produce audio.

---
 OSBindings/SDL/main.cpp | 44 +++++++++++++++++++++++------------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/OSBindings/SDL/main.cpp b/OSBindings/SDL/main.cpp
index 1573a2887..24a98b930 100644
--- a/OSBindings/SDL/main.cpp
+++ b/OSBindings/SDL/main.cpp
@@ -832,8 +832,11 @@ int main(int argc, char *argv[]) {
 			} else if(volume < 0.0 || volume > 1.0) {
 				std::cerr << "Cannot run with volume " << volume_string << "; volumes must be between 0.0 and 1.0." << std::endl;
 			} else {
-				const auto speaker = machine->audio_producer()->get_speaker();
-				if(speaker) speaker->set_output_volume(volume);
+				const auto audio_producer = machine->audio_producer();
+				if(audio_producer) {
+					const auto speaker = machine->audio_producer()->get_speaker();
+					if(speaker) speaker->set_output_volume(volume);
+				}
 			}
 		}
 	}
@@ -907,26 +910,29 @@ int main(int argc, char *argv[]) {
 		machine->scan_producer()->set_scan_target(&scan_target);
 
 		// For now, lie about audio output intentions.
-		auto speaker = machine->audio_producer()->get_speaker();
-		if(speaker) {
-			// Create an audio pipe.
-			SDL_AudioSpec desired_audio_spec;
-			SDL_AudioSpec obtained_audio_spec;
+		const auto audio_producer = machine->audio_producer();
+		if(audio_producer) {
+			auto speaker = audio_producer->get_speaker();
+			if(speaker) {
+				// Create an audio pipe.
+				SDL_AudioSpec desired_audio_spec;
+				SDL_AudioSpec obtained_audio_spec;
 
-			SDL_zero(desired_audio_spec);
-			desired_audio_spec.freq = 48000;	// TODO: how can I get SDL to reveal the output rate of this machine?
-			desired_audio_spec.format = AUDIO_S16;
-			desired_audio_spec.channels = 1 + int(speaker->get_is_stereo());
-			desired_audio_spec.samples = Uint16(SpeakerDelegate::buffered_samples);
-			desired_audio_spec.callback = SpeakerDelegate::SDL_audio_callback;
-			desired_audio_spec.userdata = &speaker_delegate;
+				SDL_zero(desired_audio_spec);
+				desired_audio_spec.freq = 48000;	// TODO: how can I get SDL to reveal the output rate of this machine?
+				desired_audio_spec.format = AUDIO_S16;
+				desired_audio_spec.channels = 1 + int(speaker->get_is_stereo());
+				desired_audio_spec.samples = Uint16(SpeakerDelegate::buffered_samples);
+				desired_audio_spec.callback = SpeakerDelegate::SDL_audio_callback;
+				desired_audio_spec.userdata = &speaker_delegate;
 
-			speaker_delegate.audio_device = SDL_OpenAudioDevice(nullptr, 0, &desired_audio_spec, &obtained_audio_spec, SDL_AUDIO_ALLOW_FREQUENCY_CHANGE);
+				speaker_delegate.audio_device = SDL_OpenAudioDevice(nullptr, 0, &desired_audio_spec, &obtained_audio_spec, SDL_AUDIO_ALLOW_FREQUENCY_CHANGE);
 
-			speaker->set_output_rate(obtained_audio_spec.freq, desired_audio_spec.samples, obtained_audio_spec.channels == 2);
-			speaker_delegate.is_stereo = obtained_audio_spec.channels == 2;
-			speaker->set_delegate(&speaker_delegate);
-			SDL_PauseAudioDevice(speaker_delegate.audio_device, 0);
+				speaker->set_output_rate(obtained_audio_spec.freq, desired_audio_spec.samples, obtained_audio_spec.channels == 2);
+				speaker_delegate.is_stereo = obtained_audio_spec.channels == 2;
+				speaker->set_delegate(&speaker_delegate);
+				SDL_PauseAudioDevice(speaker_delegate.audio_device, 0);
+			}
 		}
 
 		/*

From 88f2a2940b371fa7e03356f9dd5fc573567a7604 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 21:07:35 -0400
Subject: [PATCH 005/117] Add Enterprise source paths.

---
 OSBindings/SDL/SConstruct | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/OSBindings/SDL/SConstruct b/OSBindings/SDL/SConstruct
index 2511a5291..b5cadb6c0 100644
--- a/OSBindings/SDL/SConstruct
+++ b/OSBindings/SDL/SConstruct
@@ -31,6 +31,7 @@ SOURCES += glob.glob('../../Analyser/Static/Coleco/*.cpp')
 SOURCES += glob.glob('../../Analyser/Static/Commodore/*.cpp')
 SOURCES += glob.glob('../../Analyser/Static/Disassembler/*.cpp')
 SOURCES += glob.glob('../../Analyser/Static/DiskII/*.cpp')
+SOURCES += glob.glob('../../Analyser/Static/Enterprise/*.cpp')
 SOURCES += glob.glob('../../Analyser/Static/Macintosh/*.cpp')
 SOURCES += glob.glob('../../Analyser/Static/MSX/*.cpp')
 SOURCES += glob.glob('../../Analyser/Static/Oric/*.cpp')
@@ -79,6 +80,7 @@ SOURCES += glob.glob('../../Machines/Commodore/*.cpp')
 SOURCES += glob.glob('../../Machines/Commodore/1540/Implementation/*.cpp')
 SOURCES += glob.glob('../../Machines/Commodore/Vic-20/*.cpp')
 SOURCES += glob.glob('../../Machines/Electron/*.cpp')
+SOURCES += glob.glob('../../Machines/Enterprise/*.cpp')
 SOURCES += glob.glob('../../Machines/MasterSystem/*.cpp')
 SOURCES += glob.glob('../../Machines/MSX/*.cpp')
 SOURCES += glob.glob('../../Machines/Oric/*.cpp')

From c5a86f0ef7e71182f2f3a67ac59fc83e33822420 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 21:11:06 -0400
Subject: [PATCH 006/117] Add Enterprise parts of the static analyser.

---
 Analyser/Static/Enterprise/StaticAnalyser.cpp |  0
 Analyser/Static/Enterprise/StaticAnalyser.hpp |  0
 Analyser/Static/Enterprise/Target.hpp         | 30 +++++++++++++++++++
 Machines/Enterprise/Enterprise.cpp            | 15 +++++++++-
 4 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 Analyser/Static/Enterprise/StaticAnalyser.cpp
 create mode 100644 Analyser/Static/Enterprise/StaticAnalyser.hpp
 create mode 100644 Analyser/Static/Enterprise/Target.hpp

diff --git a/Analyser/Static/Enterprise/StaticAnalyser.cpp b/Analyser/Static/Enterprise/StaticAnalyser.cpp
new file mode 100644
index 000000000..e69de29bb
diff --git a/Analyser/Static/Enterprise/StaticAnalyser.hpp b/Analyser/Static/Enterprise/StaticAnalyser.hpp
new file mode 100644
index 000000000..e69de29bb
diff --git a/Analyser/Static/Enterprise/Target.hpp b/Analyser/Static/Enterprise/Target.hpp
new file mode 100644
index 000000000..f77f01f50
--- /dev/null
+++ b/Analyser/Static/Enterprise/Target.hpp
@@ -0,0 +1,30 @@
+//
+//  Target.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 14/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#ifndef Analyser_Static_Enterprise_Target_h
+#define Analyser_Static_Enterprise_Target_h
+
+#include "../../../Reflection/Enum.hpp"
+#include "../../../Reflection/Struct.hpp"
+#include "../StaticAnalyser.hpp"
+
+namespace Analyser {
+namespace Static {
+namespace Enterprise {
+
+struct Target: public Analyser::Static::Target, public Reflection::StructImpl<Target> {
+	Target() : Analyser::Static::Target(Machine::Enterprise) {}
+
+	// TODO: I assume there'll be relevant fields to add here.
+};
+
+}
+}
+}
+
+#endif /* Analyser_Static_Enterprise_Target_h */
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 102cbea31..50665c781 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -10,16 +10,21 @@
 
 #include "../MachineTypes.hpp"
 
+#include "../../Processors/Z80/Z80.hpp"
+
 #include "../../Analyser/Static/Enterprise/Target.hpp"
 
+
 namespace Enterprise {
 
 class ConcreteMachine:
+	public CPU::Z80::BusHandler,
 	public Machine,
 	public MachineTypes::ScanProducer,
 	public MachineTypes::TimedMachine {
 	public:
-		ConcreteMachine(const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) {
+		ConcreteMachine(const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
+			z80(*this) {
 			// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
 			set_clock_rate(4'000'000);
 
@@ -28,6 +33,14 @@ class ConcreteMachine:
 		}
 
 	private:
+		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
+
+		// MARK: - Z80::BusHandler.
+		forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
+			(void)cycle;
+			return HalfCycles(0);
+		}
+
 		// MARK: - ScanProducer
 		void set_scan_target(Outputs::Display::ScanTarget *scan_target) override {
 			(void)scan_target;

From 196c4dcdd99628aa5a762bb3bc5b2e2e28ec1149 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 21:17:09 -0400
Subject: [PATCH 007/117] Adds an appropriate ROM request.

---
 Machines/Enterprise/Enterprise.cpp | 11 ++++++++++-
 Machines/Utility/ROMCatalogue.cpp  |  5 +++++
 Machines/Utility/ROMCatalogue.hpp  |  3 +++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 50665c781..e24e582fb 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -24,10 +24,16 @@ class ConcreteMachine:
 	public MachineTypes::TimedMachine {
 	public:
 		ConcreteMachine(const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
-			z80(*this) {
+			z80_(*this) {
 			// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
 			set_clock_rate(4'000'000);
 
+			const auto request = ROM::Request(ROM::Name::EnterpriseEXOS);
+			auto roms = rom_fetcher(request);
+			if(!request.validate(roms)) {
+				throw ROMMachine::Error::MissingROMs;
+			}
+
 			(void)target;
 			(void)rom_fetcher;
 		}
@@ -35,6 +41,9 @@ class ConcreteMachine:
 	private:
 		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
 
+		std::array<uint8_t, 32 * 1024> exos_;
+		std::array<uint8_t, 256 * 1024> ram_;
+
 		// MARK: - Z80::BusHandler.
 		forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
 			(void)cycle;
diff --git a/Machines/Utility/ROMCatalogue.cpp b/Machines/Utility/ROMCatalogue.cpp
index 7a12069ff..c0f25e6a2 100644
--- a/Machines/Utility/ROMCatalogue.cpp
+++ b/Machines/Utility/ROMCatalogue.cpp
@@ -404,6 +404,11 @@ Description::Description(Name name) {
 			*this = Description(name, "DiskII", "the Disk II 13-sector state machine ROM", "state-machine-13.rom", 256, 0x62e22620u);
 		break;
 
+		case Name::EnterpriseEXOS: {
+			const std::initializer_list<std::string> filenames = {"exos.bin", "Exos (198x)(Enterprise).bin"},
+			*this = Description(name, "Enterprise", "the Enterprise EXOS ROM", filenames, 32 * 1024, 0x30b26387u);
+		} break;
+
 		case Name::Macintosh128k:	*this = Description(name, "Macintosh", "the Macintosh 128k ROM", "mac128k.rom", 64*1024, 0x6d0c8a28u);	break;
 		case Name::Macintosh512k:	*this = Description(name, "Macintosh", "the Macintosh 512k ROM", "mac512k.rom", 64*1024, 0xcf759e0d);	break;
 		case Name::MacintoshPlus: {
diff --git a/Machines/Utility/ROMCatalogue.hpp b/Machines/Utility/ROMCatalogue.hpp
index 88ec7ca5b..a9f457b95 100644
--- a/Machines/Utility/ROMCatalogue.hpp
+++ b/Machines/Utility/ROMCatalogue.hpp
@@ -71,6 +71,9 @@ enum Name {
 	DiskIIStateMachine13Sector,
 	DiskIIBoot13Sector,
 
+	// Enterprise.
+	EnterpriseEXOS,
+
 	// Macintosh.
 	Macintosh128k,
 	Macintosh512k,

From b5340c8f7416144aac744e62b9118d0c0ba8b7b6 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 21:17:35 -0400
Subject: [PATCH 008/117] Correct syntax.

---
 Machines/Utility/ROMCatalogue.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Machines/Utility/ROMCatalogue.cpp b/Machines/Utility/ROMCatalogue.cpp
index c0f25e6a2..643b72a9e 100644
--- a/Machines/Utility/ROMCatalogue.cpp
+++ b/Machines/Utility/ROMCatalogue.cpp
@@ -405,7 +405,7 @@ Description::Description(Name name) {
 		break;
 
 		case Name::EnterpriseEXOS: {
-			const std::initializer_list<std::string> filenames = {"exos.bin", "Exos (198x)(Enterprise).bin"},
+			const std::initializer_list<std::string> filenames = {"exos.bin", "Exos (198x)(Enterprise).bin"};
 			*this = Description(name, "Enterprise", "the Enterprise EXOS ROM", filenames, 32 * 1024, 0x30b26387u);
 		} break;
 

From 2a2ac1227b3751fb8af43d25db78b28efdcb2fff Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 21:29:56 -0400
Subject: [PATCH 009/117] Makes first attempt at giving the Z80 something to
 do.

---
 Machines/Enterprise/Enterprise.cpp | 74 ++++++++++++++++++++++++++----
 1 file changed, 66 insertions(+), 8 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index e24e582fb..980568ba4 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -23,7 +23,7 @@ class ConcreteMachine:
 	public MachineTypes::ScanProducer,
 	public MachineTypes::TimedMachine {
 	public:
-		ConcreteMachine(const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
+		ConcreteMachine([[maybe_unused]] const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
 			z80_(*this) {
 			// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
 			set_clock_rate(4'000'000);
@@ -34,8 +34,45 @@ class ConcreteMachine:
 				throw ROMMachine::Error::MissingROMs;
 			}
 
-			(void)target;
-			(void)rom_fetcher;
+			// Take a reasonable guess at the initial memory configuration.
+			page<0>(0x00);
+			page<1>(0x01);
+			page<2>(0xfe);
+			page<3>(0xff);
+		}
+
+		// MARK: - Z80::BusHandler.
+		forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
+			using PartialMachineCycle = CPU::Z80::PartialMachineCycle;
+			const uint16_t address = cycle.address ? *cycle.address : 0x0000;
+
+			// TODO: possibly apply an access penalty.
+
+			switch(cycle.operation) {
+				default: break;
+
+				case CPU::Z80::PartialMachineCycle::Input:
+				case CPU::Z80::PartialMachineCycle::Output:
+					assert(false);
+				break;
+
+				case CPU::Z80::PartialMachineCycle::Read:
+				case CPU::Z80::PartialMachineCycle::ReadOpcode:
+					if(read_pointers_[address >> 14]) {
+						*cycle.value = read_pointers_[address >> 14][address];
+					} else {
+						*cycle.value = 0xff;
+					}
+				break;
+
+				case CPU::Z80::PartialMachineCycle::Write:
+					if(write_pointers_[address >> 14]) {
+						write_pointers_[address >> 14][address] = *cycle.value;
+					}
+				break;
+			}
+
+			return HalfCycles(0);
 		}
 
 	private:
@@ -43,11 +80,32 @@ class ConcreteMachine:
 
 		std::array<uint8_t, 32 * 1024> exos_;
 		std::array<uint8_t, 256 * 1024> ram_;
+		const uint8_t min_ram_slot_ = 0xff - 3;
 
-		// MARK: - Z80::BusHandler.
-		forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
-			(void)cycle;
-			return HalfCycles(0);
+		const uint8_t *read_pointers_[4];
+		uint8_t *write_pointers_[4];
+		uint8_t pages_[4];
+
+		template <size_t slot> void page(uint8_t offset) {
+			pages_[slot] = offset;
+
+			if(offset < 2) {
+				page<slot>(&exos_[offset * 0x4000], nullptr);
+				return;
+			}
+
+			if(offset >= min_ram_slot_) {
+				const size_t address = (offset - min_ram_slot_) * 0x4000;
+				page<slot>(&ram_[address], &ram_[address]);
+				return;
+			}
+
+			page<slot>(nullptr, nullptr);
+		}
+
+		template <size_t slot> void page(const uint8_t *read, uint8_t *write) {
+			read_pointers_[slot] = read ? read - (slot * 0x4000) : nullptr;
+			write_pointers_[slot] = write ? write - (slot * 0x4000) : nullptr;
 		}
 
 		// MARK: - ScanProducer
@@ -61,7 +119,7 @@ class ConcreteMachine:
 
 		// MARK: - TimedMachine
 		void run_for(const Cycles cycles) override {
-			(void)cycles;
+			z80_.run_for(cycles);
 		}
 };
 

From 853914480c66bce23c94399c990546cf0a4cb1b6 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 21:40:19 -0400
Subject: [PATCH 010/117] Revised guess; there's a jump to C02E almost
 immediately.

---
 Machines/Enterprise/Enterprise.cpp | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 980568ba4..6b08963fd 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -28,17 +28,21 @@ class ConcreteMachine:
 			// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
 			set_clock_rate(4'000'000);
 
-			const auto request = ROM::Request(ROM::Name::EnterpriseEXOS);
+			constexpr ROM::Name exos_name = ROM::Name::EnterpriseEXOS;
+			const auto request = ROM::Request(exos_name);
 			auto roms = rom_fetcher(request);
 			if(!request.validate(roms)) {
 				throw ROMMachine::Error::MissingROMs;
 			}
 
+			const auto &exos = roms.find(exos_name)->second;
+			memcpy(exos_.data(), exos.data(), std::min(exos_.size(), exos.size()));
+
 			// Take a reasonable guess at the initial memory configuration.
 			page<0>(0x00);
-			page<1>(0x01);
-			page<2>(0xfe);
-			page<3>(0xff);
+			page<1>(0x00);
+			page<2>(0x00);
+			page<3>(0x00);
 		}
 
 		// MARK: - Z80::BusHandler.
@@ -52,7 +56,12 @@ class ConcreteMachine:
 				default: break;
 
 				case CPU::Z80::PartialMachineCycle::Input:
+					printf("Unhandled input: %04x\n", address);
+					assert(false);
+				break;
+
 				case CPU::Z80::PartialMachineCycle::Output:
+					printf("Unhandled output: %04x\n", address);
 					assert(false);
 				break;
 

From 3eb4dd74a23749f13a08de8c2618d92ac105cc91 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 21:45:12 -0400
Subject: [PATCH 011/117] Exposes memory control.

Machine now runs as far as trying to interact with Nick.
---
 Machines/Enterprise/Enterprise.cpp | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 6b08963fd..1b818068c 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -56,13 +56,35 @@ class ConcreteMachine:
 				default: break;
 
 				case CPU::Z80::PartialMachineCycle::Input:
-					printf("Unhandled input: %04x\n", address);
-					assert(false);
+					switch(address & 0xff) {
+						default:
+							printf("Unhandled input: %04x\n", address);
+							assert(false);
+						break;
+
+						case 0xb0:	*cycle.value = pages_[0];	break;
+						case 0xb1:	*cycle.value = pages_[1];	break;
+						case 0xb2:	*cycle.value = pages_[2];	break;
+						case 0xb3:	*cycle.value = pages_[3];	break;
+					}
 				break;
 
 				case CPU::Z80::PartialMachineCycle::Output:
-					printf("Unhandled output: %04x\n", address);
-					assert(false);
+					switch(address & 0xff) {
+						default:
+							printf("Unhandled output: %04x\n", address);
+							assert(false);
+						break;
+
+						case 0xb0:	page<0>(*cycle.value);	break;
+						case 0xb1:	page<1>(*cycle.value);	break;
+						case 0xb2:	page<2>(*cycle.value);	break;
+						case 0xb3:	page<3>(*cycle.value);	break;
+
+						case 0xbf:
+							printf("TODO: Dave sysconfig %02x\n", *cycle.value);
+						break;
+					}
 				break;
 
 				case CPU::Z80::PartialMachineCycle::Read:

From 1d1e6d182090a477bac7ff84f61ec04e38752095 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 22:19:25 -0400
Subject: [PATCH 012/117] Adds a shell of a Nick.

---
 Machines/Enterprise/Enterprise.cpp            | 32 ++++++++++++++++---
 Machines/Enterprise/Nick.cpp                  | 29 +++++++++++++++++
 Machines/Enterprise/Nick.hpp                  | 28 ++++++++++++++++
 .../Clock Signal.xcodeproj/project.pbxproj    | 10 +++++-
 4 files changed, 94 insertions(+), 5 deletions(-)
 create mode 100644 Machines/Enterprise/Nick.cpp
 create mode 100644 Machines/Enterprise/Nick.hpp

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 1b818068c..47054bb65 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -8,12 +8,15 @@
 
 #include "Enterprise.hpp"
 
+#include "Nick.hpp"
+
 #include "../MachineTypes.hpp"
 
 #include "../../Processors/Z80/Z80.hpp"
 
 #include "../../Analyser/Static/Enterprise/Target.hpp"
 
+#include "../../ClockReceiver/JustInTime.hpp"
 
 namespace Enterprise {
 
@@ -38,7 +41,13 @@ class ConcreteMachine:
 			const auto &exos = roms.find(exos_name)->second;
 			memcpy(exos_.data(), exos.data(), std::min(exos_.size(), exos.size()));
 
-			// Take a reasonable guess at the initial memory configuration.
+			// Take a reasonable guess at the initial memory configuration:
+			// put EXOS into the first bank since this is a Z80 and therefore
+			// starts from address 0; the third instruction in EXOS is a jump
+			// to $c02e so it's reasonable to assume EXOS is in the highest bank
+			// too, and it appears to act correctly if it's the first 16kb that's
+			// in the highest bank. From there I guess: all banks are initialised
+			// to 0.
 			page<0>(0x00);
 			page<1>(0x00);
 			page<2>(0x00);
@@ -76,6 +85,13 @@ class ConcreteMachine:
 							assert(false);
 						break;
 
+						case 0x80:	case 0x81:	case 0x82:	case 0x83:
+						case 0x84:	case 0x85:	case 0x86:	case 0x87:
+						case 0x88:	case 0x89:	case 0x8a:	case 0x8b:
+						case 0x8c:	case 0x8d:	case 0x8e:	case 0x8f:
+							nick_->write(address, *cycle.value);
+						break;
+
 						case 0xb0:	page<0>(*cycle.value);	break;
 						case 0xb1:	page<1>(*cycle.value);	break;
 						case 0xb2:	page<2>(*cycle.value);	break;
@@ -106,16 +122,21 @@ class ConcreteMachine:
 			return HalfCycles(0);
 		}
 
+		void flush() {
+			nick_.flush();
+		}
+
 	private:
 		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
 
+		// MARK: - Memory layout
 		std::array<uint8_t, 32 * 1024> exos_;
 		std::array<uint8_t, 256 * 1024> ram_;
 		const uint8_t min_ram_slot_ = 0xff - 3;
 
-		const uint8_t *read_pointers_[4];
-		uint8_t *write_pointers_[4];
-		uint8_t pages_[4];
+		const uint8_t *read_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
+		uint8_t *write_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
+		uint8_t pages_[4] = {0x80, 0x80, 0x80, 0x80};
 
 		template <size_t slot> void page(uint8_t offset) {
 			pages_[slot] = offset;
@@ -152,6 +173,9 @@ class ConcreteMachine:
 		void run_for(const Cycles cycles) override {
 			z80_.run_for(cycles);
 		}
+
+		// MARK: - Video.
+		JustInTimeActor<Nick> nick_;
 };
 
 }
diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
new file mode 100644
index 000000000..3c1f45d16
--- /dev/null
+++ b/Machines/Enterprise/Nick.cpp
@@ -0,0 +1,29 @@
+//
+//  Nick.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 14/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#include "Nick.hpp"
+
+#include <cstdio>
+
+using namespace Enterprise;
+
+void Nick::write(uint16_t address, uint8_t value) {
+	switch(address & 3) {
+		default:
+			printf("Unhandled Nick write: %02x -> %d\n", value, address & 3);
+		break;
+	}
+}
+
+uint8_t Nick::read([[maybe_unused]] uint16_t address) {
+	return 0xff;
+}
+
+void Nick::run_for(HalfCycles) {
+
+}
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
new file mode 100644
index 000000000..bde2c03ad
--- /dev/null
+++ b/Machines/Enterprise/Nick.hpp
@@ -0,0 +1,28 @@
+//
+//  Nick.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 14/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#ifndef Nick_hpp
+#define Nick_hpp
+
+#include <cstdint>
+#include "../../ClockReceiver/ClockReceiver.hpp"
+
+namespace Enterprise {
+
+class Nick {
+	public:
+		void write(uint16_t address, uint8_t value);
+		uint8_t read(uint16_t address);
+
+		void run_for(HalfCycles);
+};
+
+
+}
+
+#endif /* Nick_hpp */
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index 6ef07aa80..f672c30ac 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -21,6 +21,8 @@
 		4B051CA32676F52200CA44E8 /* Enterprise.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CA12676F52200CA44E8 /* Enterprise.cpp */; };
 		4B051CA826781D6500CA44E8 /* StaticAnalyser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CA726781D6500CA44E8 /* StaticAnalyser.cpp */; };
 		4B051CA926781D6500CA44E8 /* StaticAnalyser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CA726781D6500CA44E8 /* StaticAnalyser.cpp */; };
+		4B051CAC26783E2000CA44E8 /* Nick.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAA26783E2000CA44E8 /* Nick.cpp */; };
+		4B051CAD26783E2000CA44E8 /* Nick.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAA26783E2000CA44E8 /* Nick.cpp */; };
 		4B05401E219D1618001BF69C /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B05401D219D1618001BF69C /* ScanTarget.cpp */; };
 		4B05401F219D1618001BF69C /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B05401D219D1618001BF69C /* ScanTarget.cpp */; };
 		4B055A7A1FAE78A00060FFFF /* SDL2.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 4B055A771FAE78210060FFFF /* SDL2.framework */; };
@@ -1037,6 +1039,8 @@
 		4B051CA526781D6500CA44E8 /* StaticAnalyser.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = StaticAnalyser.hpp; sourceTree = "<group>"; };
 		4B051CA626781D6500CA44E8 /* Target.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = Target.hpp; sourceTree = "<group>"; };
 		4B051CA726781D6500CA44E8 /* StaticAnalyser.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = StaticAnalyser.cpp; sourceTree = "<group>"; };
+		4B051CAA26783E2000CA44E8 /* Nick.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = Nick.cpp; sourceTree = "<group>"; };
+		4B051CAB26783E2000CA44E8 /* Nick.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Nick.hpp; sourceTree = "<group>"; };
 		4B05401D219D1618001BF69C /* ScanTarget.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = ScanTarget.cpp; sourceTree = "<group>"; };
 		4B055A6A1FAE763F0060FFFF /* Clock Signal Kiosk */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = "Clock Signal Kiosk"; sourceTree = BUILT_PRODUCTS_DIR; };
 		4B055A771FAE78210060FFFF /* SDL2.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = SDL2.framework; path = ../../../../Library/Frameworks/SDL2.framework; sourceTree = SOURCE_ROOT; };
@@ -2102,8 +2106,10 @@
 		4B051C9F2676F52200CA44E8 /* Enterprise */ = {
 			isa = PBXGroup;
 			children = (
-				4B051CA02676F52200CA44E8 /* Enterprise.hpp */,
 				4B051CA12676F52200CA44E8 /* Enterprise.cpp */,
+				4B051CAA26783E2000CA44E8 /* Nick.cpp */,
+				4B051CA02676F52200CA44E8 /* Enterprise.hpp */,
+				4B051CAB26783E2000CA44E8 /* Nick.hpp */,
 			);
 			path = Enterprise;
 			sourceTree = "<group>";
@@ -5324,6 +5330,7 @@
 				4B055AAD1FAE85FD0060FFFF /* PCMTrack.cpp in Sources */,
 				4BD67DD1209BF27B00AB2146 /* Encoder.cpp in Sources */,
 				4BE2121A253FCE9C00435408 /* AppleIIgs.cpp in Sources */,
+				4B051CAD26783E2000CA44E8 /* Nick.cpp in Sources */,
 				4B89451F201967B4007DE474 /* Tape.cpp in Sources */,
 				4B055AA81FAE85EF0060FFFF /* Shifter.cpp in Sources */,
 				4BEDA3BC25B25563000C2DBD /* Decoder.cpp in Sources */,
@@ -5586,6 +5593,7 @@
 				4B8805FB1DCFF807003085B1 /* Oric.cpp in Sources */,
 				4B6ED2F0208E2F8A0047B343 /* WOZ.cpp in Sources */,
 				4B15A9FC208249BB005E6C8D /* StaticAnalyser.cpp in Sources */,
+				4B051CAC26783E2000CA44E8 /* Nick.cpp in Sources */,
 				4B5FADC01DE3BF2B00AEC565 /* Microdisc.cpp in Sources */,
 				4B0F1BDA2602FF9800B85C66 /* Video.cpp in Sources */,
 				4B051C922669C90B00CA44E8 /* ROMCatalogue.cpp in Sources */,

From 606c7709cf15b4a36f3a02be97a630aff4098221 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 22:28:31 -0400
Subject: [PATCH 013/117] Shims in enough to get the Z80 to run perpetually.

Notably I don't actually currently know how the interrupt registers work, but getting some sort of display running might be the first order of business.
---
 Machines/Enterprise/Enterprise.cpp | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 47054bb65..e476449ad 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -75,6 +75,15 @@ class ConcreteMachine:
 						case 0xb1:	*cycle.value = pages_[1];	break;
 						case 0xb2:	*cycle.value = pages_[2];	break;
 						case 0xb3:	*cycle.value = pages_[3];	break;
+
+						case 0xb4:
+							printf("TODO: interrupt enable/reset read\n");
+							*cycle.value = 0xff;
+						break;
+						case 0xb5:
+							printf("TODO: Keyboard/joystick input\n");
+							*cycle.value = 0xff;
+						break;
 					}
 				break;
 
@@ -97,6 +106,22 @@ class ConcreteMachine:
 						case 0xb2:	page<2>(*cycle.value);	break;
 						case 0xb3:	page<3>(*cycle.value);	break;
 
+						case 0xa0:	case 0xa1:	case 0xa2:	case 0xa3:
+						case 0xa4:	case 0xa5:	case 0xa6:	case 0xa7:
+						case 0xa8:	case 0xa9:	case 0xaa:	case 0xab:
+						case 0xac:	case 0xad:	case 0xae:	case 0xaf:
+							printf("TODO: audio adjust %04x <- %02x\n", address, *cycle.value);
+						break;
+
+						case 0xb4:
+							printf("TODO: interrupt enable/reset write %02x\n", *cycle.value);
+						break;
+						case 0xb5:
+							printf("TODO: Keyboard/etc %02x\n", *cycle.value);
+						break;
+						case 0xb6:
+							printf("TODO: printer output %02x\n", *cycle.value);
+						break;
 						case 0xbf:
 							printf("TODO: Dave sysconfig %02x\n", *cycle.value);
 						break;

From f90dce5c54e14b8a2260662982c27bad1ca78344 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 22:56:26 -0400
Subject: [PATCH 014/117] Take a guess at Nick timing.

---
 Machines/Enterprise/Enterprise.cpp | 40 +++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index e476449ad..e63c6c708 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -20,6 +20,42 @@
 
 namespace Enterprise {
 
+/*
+	Notes to self on timing:
+
+	Nick divides each line into 57 windows; each window lasts 16 cycles and dedicates the
+	first 10 of those to VRAM accesses, leaving the final six for a Z80 video RAM access
+	if one has been requested.
+
+	The Z80 has a separate, asynchronous 4Mhz clock. That's that.
+
+	The documentation is also very forward in emphasising that Nick generates phaselocked
+	(i.e. in-phase) PAL video.
+
+	So: 57*16 = 912 cycles/line.
+
+	A standard PAL line lasts 64µs and during that time outputs 283.7516 colour cycles.
+
+	I shall _guess_ that the Enterprise stretches each line to 284 colour cycles rather than
+	reducing it to 283.
+
+	Therefore 912 cycles occurs in 284/283.7516 * 64 µs, which would appear to give an ideal
+	clock rate of around:
+
+		14,237,536.27 Hz.
+
+	Given that there's always some leeway in a receiver, I'm modelling that as 14,237,536 cycles,
+	which means that Nick runs 444923/125000 times as fast as the Z80. Which is around 3.56 times
+	as fast.
+
+	If that's true then the 6-cycle window is around 1.69 Z80 cycles long. Given that the Z80
+	clock in an Enterprise can be stopped in half-cycle increments only, the Z80 can only be
+	guaranteed to have around a 1.19 cycle minimum for its actual access. I'm therefore further
+	postulating that the clock stoppage takes place so as to align the final cycle of a relevant
+	access over the available window.
+
+*/
+
 class ConcreteMachine:
 	public CPU::Z80::BusHandler,
 	public Machine,
@@ -60,6 +96,7 @@ class ConcreteMachine:
 			const uint16_t address = cycle.address ? *cycle.address : 0x0000;
 
 			// TODO: possibly apply an access penalty.
+			nick_ += cycle.length;
 
 			switch(cycle.operation) {
 				default: break;
@@ -200,7 +237,8 @@ class ConcreteMachine:
 		}
 
 		// MARK: - Video.
-		JustInTimeActor<Nick> nick_;
+		JustInTimeActor<Nick, HalfCycles, 444923, 125000> nick_;
+		// Cf. timing guesses above.
 };
 
 }

From 440b11708b114bfca02730ac8e9c52cd494ffeec Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 14 Jun 2021 23:11:48 -0400
Subject: [PATCH 015/117] Adds an unused CRT.

---
 Machines/Enterprise/Enterprise.cpp |  4 ++--
 Machines/Enterprise/Nick.cpp       | 18 +++++++++++++++++-
 Machines/Enterprise/Nick.hpp       |  9 +++++++++
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index e63c6c708..3964c5425 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -224,11 +224,11 @@ class ConcreteMachine:
 
 		// MARK: - ScanProducer
 		void set_scan_target(Outputs::Display::ScanTarget *scan_target) override {
-			(void)scan_target;
+			nick_.last_valid()->set_scan_target(scan_target);
 		}
 
 		Outputs::Display::ScanStatus get_scaled_scan_status() const override {
-			return Outputs::Display::ScanStatus();
+			return nick_.last_valid()->get_scaled_scan_status();
 		}
 
 		// MARK: - TimedMachine
diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 3c1f45d16..4cf9268e1 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -12,6 +12,13 @@
 
 using namespace Enterprise;
 
+Nick::Nick() :
+	crt_(16 * 57, 16, Outputs::Display::Type::PAL50, Outputs::Display::InputDataType::Red4Green4Blue4) {
+
+	// Just use RGB for now.
+	crt_.set_display_type(Outputs::Display::DisplayType::RGB);
+}
+
 void Nick::write(uint16_t address, uint8_t value) {
 	switch(address & 3) {
 		default:
@@ -25,5 +32,14 @@ uint8_t Nick::read([[maybe_unused]] uint16_t address) {
 }
 
 void Nick::run_for(HalfCycles) {
-
+}
+
+// MARK: - CRT passthroughs.
+
+void Nick::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
+	crt_.set_scan_target(scan_target);
+}
+
+Outputs::Display::ScanStatus Nick::get_scaled_scan_status() const {
+	return crt_.get_scaled_scan_status();
 }
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index bde2c03ad..69a5bcb12 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -11,15 +11,24 @@
 
 #include <cstdint>
 #include "../../ClockReceiver/ClockReceiver.hpp"
+#include "../../Outputs/CRT/CRT.hpp"
 
 namespace Enterprise {
 
 class Nick {
 	public:
+		Nick();
+
 		void write(uint16_t address, uint8_t value);
 		uint8_t read(uint16_t address);
 
 		void run_for(HalfCycles);
+
+		void set_scan_target(Outputs::Display::ScanTarget *scan_target);
+		Outputs::Display::ScanStatus get_scaled_scan_status() const;
+
+	private:
+		Outputs::CRT::CRT crt_;
 };
 
 

From a1e4389f63de06c38542de04c7c8e8f5c9d7475e Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 15 Jun 2021 17:43:13 -0400
Subject: [PATCH 016/117] Give Nick some RAM to inspect and just enough sense
 to know when it should reload its line parameter table.

---
 Machines/Enterprise/Enterprise.cpp | 13 +++++++------
 Machines/Enterprise/Nick.cpp       | 23 ++++++++++++++++++++---
 Machines/Enterprise/Nick.hpp       |  7 ++++++-
 3 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 3964c5425..5896c881b 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -63,7 +63,8 @@ class ConcreteMachine:
 	public MachineTypes::TimedMachine {
 	public:
 		ConcreteMachine([[maybe_unused]] const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
-			z80_(*this) {
+			z80_(*this),
+			nick_(ram_.end() - 65536) {
 			// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
 			set_clock_rate(4'000'000);
 
@@ -189,11 +190,9 @@ class ConcreteMachine:
 		}
 
 	private:
-		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
-
 		// MARK: - Memory layout
-		std::array<uint8_t, 32 * 1024> exos_;
 		std::array<uint8_t, 256 * 1024> ram_;
+		std::array<uint8_t, 32 * 1024> exos_;
 		const uint8_t min_ram_slot_ = 0xff - 3;
 
 		const uint8_t *read_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
@@ -209,7 +208,8 @@ class ConcreteMachine:
 			}
 
 			if(offset >= min_ram_slot_) {
-				const size_t address = (offset - min_ram_slot_) * 0x4000;
+				const auto ram_floor = 4194304 - ram_.size();
+				const size_t address = offset * 0x4000 - ram_floor;
 				page<slot>(&ram_[address], &ram_[address]);
 				return;
 			}
@@ -236,7 +236,8 @@ class ConcreteMachine:
 			z80_.run_for(cycles);
 		}
 
-		// MARK: - Video.
+		// MARK: - Chips.
+		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
 		JustInTimeActor<Nick, HalfCycles, 444923, 125000> nick_;
 		// Cf. timing guesses above.
 };
diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 4cf9268e1..3cd39de86 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -12,17 +12,34 @@
 
 using namespace Enterprise;
 
-Nick::Nick() :
-	crt_(16 * 57, 16, Outputs::Display::Type::PAL50, Outputs::Display::InputDataType::Red4Green4Blue4) {
+Nick::Nick(const uint8_t *ram) :
+	crt_(16 * 57, 16, Outputs::Display::Type::PAL50, Outputs::Display::InputDataType::Red4Green4Blue4),
+	ram_(ram) {
 
 	// Just use RGB for now.
 	crt_.set_display_type(Outputs::Display::DisplayType::RGB);
 }
 
 void Nick::write(uint16_t address, uint8_t value) {
+	printf("Nick write: %02x -> %d\n", value, address & 3);
 	switch(address & 3) {
 		default:
-			printf("Unhandled Nick write: %02x -> %d\n", value, address & 3);
+			printf("Unhandled\n");
+		break;
+
+		case 2:
+			line_parameter_base_ = uint16_t((line_parameter_base_ & 0xf000) | (value << 4));
+		break;
+		case 3:
+			line_parameter_base_ = uint16_t((line_parameter_base_ & 0x0ff0) | (value << 12));
+
+			// Still a mystery to me: the exact meaning of the top two bits here. For now
+			// just treat a 0 -> 1 transition of the MSB as a forced frame restart.
+			if((value^line_parameter_control_) & value & 0x80) {
+				// TODO: restart frame.
+				printf("Should restart frame from %04x\n", line_parameter_base_);
+			}
+			line_parameter_control_ = value & 0xc0;
 		break;
 	}
 }
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 69a5bcb12..d38aa59a3 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -17,7 +17,7 @@ namespace Enterprise {
 
 class Nick {
 	public:
-		Nick();
+		Nick(const uint8_t *ram);
 
 		void write(uint16_t address, uint8_t value);
 		uint8_t read(uint16_t address);
@@ -29,6 +29,11 @@ class Nick {
 
 	private:
 		Outputs::CRT::CRT crt_;
+		const uint8_t *const ram_;
+
+		uint8_t line_parameter_control_ = 0xc0;
+		uint16_t line_parameter_base_ = 0x0000;
+		int horizontal_counter_ = 0;
 };
 
 

From 90b8163d5465adcaa3e56c6c30f3060ace85a71e Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 15 Jun 2021 17:44:39 -0400
Subject: [PATCH 017/117] Add exposition.

---
 Machines/Enterprise/Enterprise.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 5896c881b..c9a0151ab 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -207,6 +207,10 @@ class ConcreteMachine:
 				return;
 			}
 
+			// Of whatever size of RAM I've declared above, use only the final portion.
+			// This correlated with Nick always having been handed the final 64kb and,
+			// at least while the RAM is the first thing declared above, does a little
+			// to benefit data locality. Albeit not in a useful sense.
 			if(offset >= min_ram_slot_) {
 				const auto ram_floor = 4194304 - ram_.size();
 				const size_t address = offset * 0x4000 - ram_floor;

From 60cf8486bb6c4b4c8095a795c76731798f0ff967 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 15 Jun 2021 18:57:14 -0400
Subject: [PATCH 018/117] Makes a genuine attempt at real line counting.

No output yet though.
---
 Machines/Enterprise/Nick.cpp | 60 ++++++++++++++++++++++++++++++++++--
 Machines/Enterprise/Nick.hpp |  9 ++++++
 2 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 3cd39de86..0641b85da 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -36,8 +36,13 @@ void Nick::write(uint16_t address, uint8_t value) {
 			// Still a mystery to me: the exact meaning of the top two bits here. For now
 			// just treat a 0 -> 1 transition of the MSB as a forced frame restart.
 			if((value^line_parameter_control_) & value & 0x80) {
-				// TODO: restart frame.
 				printf("Should restart frame from %04x\n", line_parameter_base_);
+
+				// For now: just force this to be the final line of this mode block.
+				// I'm unclear whether I should also reset the horizontal counter
+				// (i.e. completely abandon current video phase).
+				lines_remaining_ = 0xff;
+				line_parameters_[1] |= 1;
 			}
 			line_parameter_control_ = value & 0xc0;
 		break;
@@ -48,7 +53,58 @@ uint8_t Nick::read([[maybe_unused]] uint16_t address) {
 	return 0xff;
 }
 
-void Nick::run_for(HalfCycles) {
+void Nick::run_for(HalfCycles duration) {
+	constexpr int line_length = 912;
+
+	int clocks_remaining = duration.as<int>();
+	while(clocks_remaining) {
+		// Determine how many cycles are left this line.
+		const int clocks_this_line = std::min(clocks_remaining, line_length - horizontal_counter_);
+
+		// Convert that into a [start/current] and end window.
+		int window = horizontal_counter_ >> 4;
+		const int end_window = (horizontal_counter_ + clocks_this_line) >> 4;
+
+		// Advance the line counters.
+		clocks_remaining -= clocks_this_line;
+		horizontal_counter_ = (horizontal_counter_ + clocks_this_line) % line_length;
+
+		// Do nothing if a window boundary isn't crossed.
+		if(window == end_window) continue;
+
+		// If this is within the first 8 cycles of the line, [possibly] fetch
+		// the relevant part of the line parameters.
+		if(should_reload_line_parameters_ && window < 8) {
+			int fetch_spot = window;
+			while(fetch_spot < end_window && fetch_spot < 8) {
+				line_parameters_[(fetch_spot << 1)] = ram_[line_parameter_pointer_];
+				line_parameters_[(fetch_spot << 1) + 1] = ram_[line_parameter_pointer_ + 1];
+				line_parameter_pointer_ += 2;
+				++fetch_spot;
+			}
+
+			// If all parameters have been loaded, set appropriate fields.
+			if(fetch_spot == 8) {
+				should_reload_line_parameters_ = false;
+
+				// Set length of mode line.
+				lines_remaining_ = line_parameters_[0];
+			}
+		}
+
+		// Check for end of line.
+		if(!horizontal_counter_) {
+			++lines_remaining_;
+			if(!lines_remaining_) {
+				should_reload_line_parameters_ = true;
+
+				// Check for end-of-frame.
+				if(line_parameters_[1] & 1) {
+					line_parameter_pointer_ = line_parameter_base_;
+				}
+			}
+		}
+	}
 }
 
 // MARK: - CRT passthroughs.
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index d38aa59a3..a5088cc6f 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -31,9 +31,18 @@ class Nick {
 		Outputs::CRT::CRT crt_;
 		const uint8_t *const ram_;
 
+		// CPU-provided state.
 		uint8_t line_parameter_control_ = 0xc0;
 		uint16_t line_parameter_base_ = 0x0000;
+
+		// Ephemerals, related to current video position.
 		int horizontal_counter_ = 0;
+		uint16_t line_parameter_pointer_ = 0x0000;
+		uint8_t line_parameters_[16];
+		bool should_reload_line_parameters_ = false;
+
+		// Current mode line parameters.
+		uint8_t lines_remaining_ = 0x00;
 };
 
 

From 6a7eb832cc63a93063797580af7e2e4e692cabe6 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 15 Jun 2021 20:55:58 -0400
Subject: [PATCH 019/117] Introduces almost-stable block-level frame
 generation.

---
 Machines/Enterprise/Nick.cpp | 122 ++++++++++++++++++++++++++++++++++-
 Machines/Enterprise/Nick.hpp |  23 +++++++
 2 files changed, 144 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 0641b85da..2ab68c7d3 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -10,10 +10,28 @@
 
 #include <cstdio>
 
+namespace  {
+
+uint16_t mapped_colour(uint8_t source) {
+	// On the Enterprise, red and green are 3-bit quantities; blue is a 2-bit quantity.
+	const int red	= ((source&0x01) << 2) | ((source&0x08) >> 2) | ((source&0x40) >> 6);
+	const int green	= ((source&0x02) << 1) | ((source&0x10) >> 3) | ((source&0x80) >> 7);
+	const int blue	= ((source&0x04) >> 1) | ((source&0x20) >> 5);
+
+	// Duplicate bits where necessary to map to a full 4-bit range per channel.
+	return uint16_t(
+		(red << 9) + ((red&0x4) << 6) +
+		(green << 5) + ((green&0x4) << 2) +
+		(blue << 2) + blue
+	);
+}
+
+}
+
 using namespace Enterprise;
 
 Nick::Nick(const uint8_t *ram) :
-	crt_(16 * 57, 16, Outputs::Display::Type::PAL50, Outputs::Display::InputDataType::Red4Green4Blue4),
+	crt_(57, 1, Outputs::Display::Type::PAL50, Outputs::Display::InputDataType::Red4Green4Blue4),
 	ram_(ram) {
 
 	// Just use RGB for now.
@@ -27,6 +45,10 @@ void Nick::write(uint16_t address, uint8_t value) {
 			printf("Unhandled\n");
 		break;
 
+		case 1:
+			flush_border();
+			border_colour_ = mapped_colour(value);
+		break;
 		case 2:
 			line_parameter_base_ = uint16_t((line_parameter_base_ & 0xf000) | (value << 4));
 		break;
@@ -89,6 +111,93 @@ void Nick::run_for(HalfCycles duration) {
 
 				// Set length of mode line.
 				lines_remaining_ = line_parameters_[0];
+
+				// Determine the line data pointers.
+				line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
+				line_data_pointer_[1] = uint16_t(line_parameters_[6] | (line_parameters_[7] << 8));
+
+				// Set the output mode and margin.
+				mode_ = Mode((line_parameters_[1] >> 1)&7);
+				left_margin_ = line_parameters_[2] & 0x3f;
+				right_margin_ = line_parameters_[3] & 0x3f;
+
+				if(mode_ == Mode::Vsync) {
+					state_ = State::Blank;
+				} else {
+					// The first ten windows are occupied by the horizontal sync and
+					// colour burst; if left signalled before then, begin in pixels.
+					state_ = left_margin_ > 10 ? State::Border : State::Pixels;
+				}
+			}
+		}
+
+		// HSYNC is signalled for four windows at the start of the line.
+		if(window < 4 && end_window >= 4) {
+			crt_.output_sync(4);
+			window = 4;
+		}
+
+		// Deal with vsync mode out here.
+		if(mode_ == Mode::Vsync) {
+			while(window < end_window) {
+				int next_event = end_window;
+				if(window < left_margin_) next_event = std::min(next_event, left_margin_);
+				if(window < right_margin_) next_event = std::min(next_event, right_margin_);
+
+				if(state_ == State::Blank) {
+					crt_.output_blank(next_event - window);
+				} else {
+					crt_.output_sync(next_event - window);
+				}
+
+				window = next_event;
+				if(window == left_margin_) state_ = State::Sync;
+				if(window == right_margin_) state_ = State::Blank;
+			}
+		} else {
+			// If present then the colour burst is output for the period from
+			// the start of window 6 to the end of window 10.
+			if(window < 10 && end_window >= 10) {
+				crt_.output_blank(2);
+				crt_.output_colour_burst(4, 0);	// TODO: try to determine actual phase.
+				window = 10;
+			}
+
+			while(window < end_window) {
+				int next_event = end_window;
+				if(window < left_margin_) next_event = std::min(next_event, left_margin_);
+				if(window < right_margin_) next_event = std::min(next_event, right_margin_);
+
+				if(state_ == State::Border) {
+					border_duration_ += next_event - window;
+				} else {
+					// TODO: something proper here.
+					uint16_t *const colour_pointer = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
+					if(colour_pointer) *colour_pointer = 0xfff;
+					crt_.output_level(next_event - window);
+				}
+
+				window = next_event;
+				if(window == left_margin_) {
+					flush_border();
+					state_ = State::Pixels;
+
+					// TODO: probably allocate some pixels here?
+				}
+				if(window == right_margin_) {
+					state_ = State::Border;
+
+					// TODO: probably output pixels here?
+				}
+			}
+
+			// Finish up the line.
+			if(!horizontal_counter_) {
+				if(state_ == State::Border) {
+					flush_border();
+				} else {
+					// TODO: output pixels.
+				}
 			}
 		}
 
@@ -103,10 +212,21 @@ void Nick::run_for(HalfCycles duration) {
 					line_parameter_pointer_ = line_parameter_base_;
 				}
 			}
+
+			// TODO: should reload line data pointers?
 		}
 	}
 }
 
+void Nick::flush_border() {
+	if(!border_duration_) return;
+
+	uint16_t *const colour_pointer = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
+	if(colour_pointer) *colour_pointer = border_colour_;
+	crt_.output_level(border_duration_);
+	border_duration_ = 0;
+}
+
 // MARK: - CRT passthroughs.
 
 void Nick::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index a5088cc6f..48693e8a6 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -34,15 +34,38 @@ class Nick {
 		// CPU-provided state.
 		uint8_t line_parameter_control_ = 0xc0;
 		uint16_t line_parameter_base_ = 0x0000;
+		uint16_t border_colour_ = 0;
 
 		// Ephemerals, related to current video position.
 		int horizontal_counter_ = 0;
 		uint16_t line_parameter_pointer_ = 0x0000;
 		uint8_t line_parameters_[16];
 		bool should_reload_line_parameters_ = false;
+		uint16_t line_data_pointer_[2];
 
 		// Current mode line parameters.
 		uint8_t lines_remaining_ = 0x00;
+		int left_margin_ = 0, right_margin_ = 0;
+		enum class Mode {
+			Vsync,
+			Pixel,
+			Attr,
+			CH256,
+			CH128,
+			CH64,
+			Unused,
+			LPixel,
+		} mode_ = Mode::Vsync;
+		enum class State {
+			Sync,
+			Border,
+			Pixels,
+			Blank,
+		} state_ = State::Sync;
+
+		// An accumulator for border output regions.
+		int border_duration_ = 0;
+		void flush_border();
 };
 
 

From 6c9dacbe89691159e8fc858739aa69f56f2a2b34 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 15 Jun 2021 21:31:07 -0400
Subject: [PATCH 020/117] Stabilises display, albeit that top border mode now
 appears to be off.

---
 Machines/Enterprise/Nick.cpp | 92 ++++++++++++++++++++----------------
 1 file changed, 50 insertions(+), 42 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 2ab68c7d3..ce669020b 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -105,6 +105,18 @@ void Nick::run_for(HalfCycles duration) {
 				++fetch_spot;
 			}
 
+			// Special: set mode as soon as it's known. It'll be needed at the end of HSYNC.
+			if(!window) {
+				mode_ = Mode((line_parameters_[1] >> 1)&7);
+				if(mode_ == Mode::Vsync) {
+					state_ = State::Blank;
+				} else {
+					// The first ten windows are occupied by the horizontal sync and
+					// colour burst; if left signalled before then, begin in pixels.
+					state_ = left_margin_ > 10 ? State::Border : State::Pixels;
+				}
+			}
+
 			// If all parameters have been loaded, set appropriate fields.
 			if(fetch_spot == 8) {
 				should_reload_line_parameters_ = false;
@@ -117,21 +129,13 @@ void Nick::run_for(HalfCycles duration) {
 				line_data_pointer_[1] = uint16_t(line_parameters_[6] | (line_parameters_[7] << 8));
 
 				// Set the output mode and margin.
-				mode_ = Mode((line_parameters_[1] >> 1)&7);
 				left_margin_ = line_parameters_[2] & 0x3f;
 				right_margin_ = line_parameters_[3] & 0x3f;
-
-				if(mode_ == Mode::Vsync) {
-					state_ = State::Blank;
-				} else {
-					// The first ten windows are occupied by the horizontal sync and
-					// colour burst; if left signalled before then, begin in pixels.
-					state_ = left_margin_ > 10 ? State::Border : State::Pixels;
-				}
 			}
 		}
 
 		// HSYNC is signalled for four windows at the start of the line.
+		// I currently belive this happens regardless of Vsync mode.
 		if(window < 4 && end_window >= 4) {
 			crt_.output_sync(4);
 			window = 4;
@@ -139,20 +143,22 @@ void Nick::run_for(HalfCycles duration) {
 
 		// Deal with vsync mode out here.
 		if(mode_ == Mode::Vsync) {
-			while(window < end_window) {
-				int next_event = end_window;
-				if(window < left_margin_) next_event = std::min(next_event, left_margin_);
-				if(window < right_margin_) next_event = std::min(next_event, right_margin_);
+			if(window >= 4) {
+				while(window < end_window) {
+					int next_event = end_window;
+					if(window < left_margin_) next_event = std::min(next_event, left_margin_);
+					if(window < right_margin_) next_event = std::min(next_event, right_margin_);
 
-				if(state_ == State::Blank) {
-					crt_.output_blank(next_event - window);
-				} else {
-					crt_.output_sync(next_event - window);
+					if(state_ == State::Blank) {
+						crt_.output_blank(next_event - window);
+					} else {
+						crt_.output_sync(next_event - window);
+					}
+
+					window = next_event;
+					if(window == left_margin_) state_ = State::Sync;
+					if(window == right_margin_) state_ = State::Blank;
 				}
-
-				window = next_event;
-				if(window == left_margin_) state_ = State::Sync;
-				if(window == right_margin_) state_ = State::Blank;
 			}
 		} else {
 			// If present then the colour burst is output for the period from
@@ -163,31 +169,33 @@ void Nick::run_for(HalfCycles duration) {
 				window = 10;
 			}
 
-			while(window < end_window) {
-				int next_event = end_window;
-				if(window < left_margin_) next_event = std::min(next_event, left_margin_);
-				if(window < right_margin_) next_event = std::min(next_event, right_margin_);
+			if(window >= 10) {
+				while(window < end_window) {
+					int next_event = end_window;
+					if(window < left_margin_) next_event = std::min(next_event, left_margin_);
+					if(window < right_margin_) next_event = std::min(next_event, right_margin_);
 
-				if(state_ == State::Border) {
-					border_duration_ += next_event - window;
-				} else {
-					// TODO: something proper here.
-					uint16_t *const colour_pointer = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
-					if(colour_pointer) *colour_pointer = 0xfff;
-					crt_.output_level(next_event - window);
-				}
+					if(state_ == State::Border) {
+						border_duration_ += next_event - window;
+					} else {
+						// TODO: something proper here.
+						uint16_t *const colour_pointer = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
+						if(colour_pointer) *colour_pointer = 0xfff;
+						crt_.output_level(next_event - window);
+					}
 
-				window = next_event;
-				if(window == left_margin_) {
-					flush_border();
-					state_ = State::Pixels;
+					window = next_event;
+					if(window == left_margin_) {
+						flush_border();
+						state_ = State::Pixels;
 
-					// TODO: probably allocate some pixels here?
-				}
-				if(window == right_margin_) {
-					state_ = State::Border;
+						// TODO: probably allocate some pixels here?
+					}
+					if(window == right_margin_) {
+						state_ = State::Border;
 
-					// TODO: probably output pixels here?
+						// TODO: probably output pixels here?
+					}
 				}
 			}
 

From 5fc91effb558ec81cf4d2ff730afba7861e18f5d Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 15 Jun 2021 21:48:11 -0400
Subject: [PATCH 021/117] Corrects top border.

---
 Machines/Enterprise/Nick.cpp | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index ce669020b..b5456d3b6 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -106,8 +106,13 @@ void Nick::run_for(HalfCycles duration) {
 			}
 
 			// Special: set mode as soon as it's known. It'll be needed at the end of HSYNC.
-			if(!window) {
+			if(window < 2 && fetch_spot >= 2) {
+				// Set the output mode and margin.
+				left_margin_ = line_parameters_[2] & 0x3f;
+				right_margin_ = line_parameters_[3] & 0x3f;
 				mode_ = Mode((line_parameters_[1] >> 1)&7);
+
+				// Act as if proper state transitions had occurred while HSYNC is being output.
 				if(mode_ == Mode::Vsync) {
 					state_ = State::Blank;
 				} else {
@@ -127,10 +132,6 @@ void Nick::run_for(HalfCycles duration) {
 				// Determine the line data pointers.
 				line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
 				line_data_pointer_[1] = uint16_t(line_parameters_[6] | (line_parameters_[7] << 8));
-
-				// Set the output mode and margin.
-				left_margin_ = line_parameters_[2] & 0x3f;
-				right_margin_ = line_parameters_[3] & 0x3f;
 			}
 		}
 

From e94e051c87db5a1c3b3b79c26f3f3f33de2b11c1 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 15 Jun 2021 22:03:41 -0400
Subject: [PATCH 022/117] Adds an allocator for pixels.

---
 Machines/Enterprise/Nick.cpp | 38 +++++++++++++++++++++++++++---------
 Machines/Enterprise/Nick.hpp |  6 ++++++
 2 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index b5456d3b6..0068d6dd9 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -179,23 +179,35 @@ void Nick::run_for(HalfCycles duration) {
 					if(state_ == State::Border) {
 						border_duration_ += next_event - window;
 					} else {
-						// TODO: something proper here.
-						uint16_t *const colour_pointer = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
-						if(colour_pointer) *colour_pointer = 0xfff;
-						crt_.output_level(next_event - window);
+						if(!allocated_pointer_) {
+							flush_pixels();
+							pixel_pointer_ = allocated_pointer_ = reinterpret_cast<uint16_t *>(crt_.begin_data(allocation_size));
+						}
+
+						// TODO: real pixels.
+						if(allocated_pointer_) {
+							for(int c = 0; c < next_event - window; c++) {
+								pixel_pointer_[0] = uint16_t(0xfff ^ (window + c));
+								++pixel_pointer_;
+							}
+						} else {
+							pixel_pointer_ += next_event - window;
+						}
+
+						pixel_duration_ += next_event - window;
+						if(pixel_pointer_ - allocated_pointer_ == allocation_size) {
+							flush_pixels();
+						}
 					}
 
 					window = next_event;
 					if(window == left_margin_) {
 						flush_border();
 						state_ = State::Pixels;
-
-						// TODO: probably allocate some pixels here?
 					}
 					if(window == right_margin_) {
+						flush_pixels();
 						state_ = State::Border;
-
-						// TODO: probably output pixels here?
 					}
 				}
 			}
@@ -205,7 +217,7 @@ void Nick::run_for(HalfCycles duration) {
 				if(state_ == State::Border) {
 					flush_border();
 				} else {
-					// TODO: output pixels.
+					flush_pixels();
 				}
 			}
 		}
@@ -236,6 +248,14 @@ void Nick::flush_border() {
 	border_duration_ = 0;
 }
 
+void Nick::flush_pixels() {
+	if(!pixel_duration_) return;
+	crt_.output_data(pixel_duration_, size_t(pixel_pointer_ - allocated_pointer_));
+	pixel_duration_ = 0;
+	pixel_pointer_ = nullptr;
+	allocated_pointer_ = nullptr;
+}
+
 // MARK: - CRT passthroughs.
 
 void Nick::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 48693e8a6..5f99cb0f2 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -66,6 +66,12 @@ class Nick {
 		// An accumulator for border output regions.
 		int border_duration_ = 0;
 		void flush_border();
+
+		// The destination for new pixels.
+		static constexpr int allocation_size = 320;
+		uint16_t *pixel_pointer_ = nullptr, *allocated_pointer_ = nullptr;
+		int pixel_duration_ = 0;
+		void flush_pixels();
 };
 
 

From e5e988b28f56e1d38c83f9028a37d81101aa723b Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 15 Jun 2021 22:31:50 -0400
Subject: [PATCH 023/117] Adds an incorrect assumed-pixel-mode serialiser.

This actually shows something a bit like the Enterprise boot logo.
---
 Machines/Enterprise/Nick.cpp | 29 +++++++++++++++++++++++++++--
 Machines/Enterprise/Nick.hpp |  2 +-
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 0068d6dd9..8296b2b7a 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -187,8 +187,33 @@ void Nick::run_for(HalfCycles duration) {
 						// TODO: real pixels.
 						if(allocated_pointer_) {
 							for(int c = 0; c < next_event - window; c++) {
-								pixel_pointer_[0] = uint16_t(0xfff ^ (window + c));
-								++pixel_pointer_;
+//								pixel_pointer_[0] = uint16_t(0xfff ^ (window + c));
+
+//								++pixel_pointer_;
+
+								// Hard-coded here: 1bpp, pixel mode.
+								const uint8_t pixels[2] = { ram_[line_data_pointer_[0]], ram_[line_data_pointer_[0]+1] };
+								line_data_pointer_[0] += 2;
+
+								pixel_pointer_[0] = (pixels[0] & 0x80) ? 0xffff : 0x0000;
+								pixel_pointer_[1] = (pixels[0] & 0x40) ? 0xffff : 0x0000;
+								pixel_pointer_[2] = (pixels[0] & 0x20) ? 0xffff : 0x0000;
+								pixel_pointer_[3] = (pixels[0] & 0x10) ? 0xffff : 0x0000;
+								pixel_pointer_[4] = (pixels[0] & 0x08) ? 0xffff : 0x0000;
+								pixel_pointer_[5] = (pixels[0] & 0x04) ? 0xffff : 0x0000;
+								pixel_pointer_[6] = (pixels[0] & 0x02) ? 0xffff : 0x0000;
+								pixel_pointer_[7] = (pixels[0] & 0x01) ? 0xffff : 0x0000;
+								pixel_pointer_[8] = (pixels[1] & 0x80) ? 0xffff : 0x0000;
+								pixel_pointer_[9] = (pixels[1] & 0x40) ? 0xffff : 0x0000;
+								pixel_pointer_[10] = (pixels[1] & 0x20) ? 0xffff : 0x0000;
+								pixel_pointer_[11] = (pixels[1] & 0x10) ? 0xffff : 0x0000;
+								pixel_pointer_[12] = (pixels[1] & 0x08) ? 0xffff : 0x0000;
+								pixel_pointer_[13] = (pixels[1] & 0x04) ? 0xffff : 0x0000;
+								pixel_pointer_[14] = (pixels[1] & 0x02) ? 0xffff : 0x0000;
+								pixel_pointer_[15] = (pixels[1] & 0x01) ? 0xffff : 0x0000;
+								pixel_pointer_ += 16;
+
+								// TODO: possibly flush here?
 							}
 						} else {
 							pixel_pointer_ += next_event - window;
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 5f99cb0f2..424ba8b1c 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -68,7 +68,7 @@ class Nick {
 		void flush_border();
 
 		// The destination for new pixels.
-		static constexpr int allocation_size = 320;
+		static constexpr int allocation_size = 800; // TODO: pick an appropriate length once the serialiser is working correctly.
 		uint16_t *pixel_pointer_ = nullptr, *allocated_pointer_ = nullptr;
 		int pixel_duration_ = 0;
 		void flush_pixels();

From d9142d5427893ab9bd8922f8f868e1a5637d09c5 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 15 Jun 2021 22:39:44 -0400
Subject: [PATCH 024/117] Adjusts declared scale, accurately to communicate
 pixel clock.

---
 Machines/Enterprise/Nick.cpp | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 8296b2b7a..42c492322 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -31,7 +31,7 @@ uint16_t mapped_colour(uint8_t source) {
 using namespace Enterprise;
 
 Nick::Nick(const uint8_t *ram) :
-	crt_(57, 1, Outputs::Display::Type::PAL50, Outputs::Display::InputDataType::Red4Green4Blue4),
+	crt_(57*16, 16, Outputs::Display::Type::PAL50, Outputs::Display::InputDataType::Red4Green4Blue4),
 	ram_(ram) {
 
 	// Just use RGB for now.
@@ -138,7 +138,7 @@ void Nick::run_for(HalfCycles duration) {
 		// HSYNC is signalled for four windows at the start of the line.
 		// I currently belive this happens regardless of Vsync mode.
 		if(window < 4 && end_window >= 4) {
-			crt_.output_sync(4);
+			crt_.output_sync(4*16);
 			window = 4;
 		}
 
@@ -151,9 +151,9 @@ void Nick::run_for(HalfCycles duration) {
 					if(window < right_margin_) next_event = std::min(next_event, right_margin_);
 
 					if(state_ == State::Blank) {
-						crt_.output_blank(next_event - window);
+						crt_.output_blank((next_event - window)*16);
 					} else {
-						crt_.output_sync(next_event - window);
+						crt_.output_sync((next_event - window)*16);
 					}
 
 					window = next_event;
@@ -165,8 +165,8 @@ void Nick::run_for(HalfCycles duration) {
 			// If present then the colour burst is output for the period from
 			// the start of window 6 to the end of window 10.
 			if(window < 10 && end_window >= 10) {
-				crt_.output_blank(2);
-				crt_.output_colour_burst(4, 0);	// TODO: try to determine actual phase.
+				crt_.output_blank(2*16);
+				crt_.output_colour_burst(4*16, 0);	// TODO: try to determine actual phase.
 				window = 10;
 			}
 
@@ -269,13 +269,13 @@ void Nick::flush_border() {
 
 	uint16_t *const colour_pointer = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
 	if(colour_pointer) *colour_pointer = border_colour_;
-	crt_.output_level(border_duration_);
+	crt_.output_level(border_duration_*16);
 	border_duration_ = 0;
 }
 
 void Nick::flush_pixels() {
 	if(!pixel_duration_) return;
-	crt_.output_data(pixel_duration_, size_t(pixel_pointer_ - allocated_pointer_));
+	crt_.output_data(pixel_duration_*16, size_t(pixel_pointer_ - allocated_pointer_));
 	pixel_duration_ = 0;
 	pixel_pointer_ = nullptr;
 	allocated_pointer_ = nullptr;

From cbac48da863205c85554fba26b81993586d16e09 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 16 Jun 2021 20:43:22 -0400
Subject: [PATCH 025/117] Attempts full run at pixel mode.

---
 Machines/Enterprise/Nick.cpp | 185 +++++++++++++++++++++++++----------
 Machines/Enterprise/Nick.hpp |  11 ++-
 2 files changed, 146 insertions(+), 50 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 42c492322..6f6de05ce 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -19,11 +19,16 @@ uint16_t mapped_colour(uint8_t source) {
 	const int blue	= ((source&0x04) >> 1) | ((source&0x20) >> 5);
 
 	// Duplicate bits where necessary to map to a full 4-bit range per channel.
-	return uint16_t(
-		(red << 9) + ((red&0x4) << 6) +
-		(green << 5) + ((green&0x4) << 2) +
-		(blue << 2) + blue
-	);
+	const uint8_t parts[2] = {
+		uint8_t(
+			(red << 1) + ((red&0x4) >> 3)
+		),
+		uint8_t(
+			(green << 5) + ((green&0x4) << 2) +
+			(blue << 2) + blue
+		)
+	};
+	return *reinterpret_cast<const uint16_t *>(parts);
 }
 
 }
@@ -41,10 +46,12 @@ Nick::Nick(const uint8_t *ram) :
 void Nick::write(uint16_t address, uint8_t value) {
 	printf("Nick write: %02x -> %d\n", value, address & 3);
 	switch(address & 3) {
-		default:
-			printf("Unhandled\n");
+		case 0:
+			// Ignored: everything to do with external colour.
+			for(int c = 0; c < 8; c++) {
+				palette_[c + 8] = mapped_colour(uint8_t(((value & 0x1f) << 3) + c));
+			}
 		break;
-
 		case 1:
 			flush_border();
 			border_colour_ = mapped_colour(value);
@@ -107,10 +114,22 @@ void Nick::run_for(HalfCycles duration) {
 
 			// Special: set mode as soon as it's known. It'll be needed at the end of HSYNC.
 			if(window < 2 && fetch_spot >= 2) {
-				// Set the output mode and margin.
+				// Determine the margins.
 				left_margin_ = line_parameters_[2] & 0x3f;
 				right_margin_ = line_parameters_[3] & 0x3f;
+
+				// Determine the mode and depth, and hence the column size.
 				mode_ = Mode((line_parameters_[1] >> 1)&7);
+				bpp_ = 1 << ((line_parameters_[1] >> 5)&3);
+				switch(mode_) {
+					default:
+					case Mode::Pixel:	column_size_ = 16 / bpp_;	break;
+//					case Mode::CH64:
+//					case Mode::CH128:
+//					case Mode::CH256:
+//					case Mode::LPixel:	column_size_ = 8 / bpp_;	break;
+//					case Mode::Attr:	column_size_ = 8;			break;
+				}
 
 				// Act as if proper state transitions had occurred while HSYNC is being output.
 				if(mode_ == Mode::Vsync) {
@@ -132,6 +151,11 @@ void Nick::run_for(HalfCycles duration) {
 				// Determine the line data pointers.
 				line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
 				line_data_pointer_[1] = uint16_t(line_parameters_[6] | (line_parameters_[7] << 8));
+
+				// Populate the first eight colours of the palette.
+				for(int c = 0; c < 8; c++) {
+					palette_[c] = mapped_colour(line_parameters_[8 + c]);
+				}
 			}
 		}
 
@@ -179,50 +203,48 @@ void Nick::run_for(HalfCycles duration) {
 					if(state_ == State::Border) {
 						border_duration_ += next_event - window;
 					} else {
-						if(!allocated_pointer_) {
-							flush_pixels();
-							pixel_pointer_ = allocated_pointer_ = reinterpret_cast<uint16_t *>(crt_.begin_data(allocation_size));
-						}
+#define DispatchBpp(func) \
+	switch(bpp_) {	\
+		default:	\
+		case 1: func<1>(pixel_pointer_, output_duration);	break;	\
+		case 2: func<2>(pixel_pointer_, output_duration);	break;	\
+		case 4: func<4>(pixel_pointer_, output_duration);	break;	\
+		case 8: func<8>(pixel_pointer_, output_duration);	break;	\
+	}
 
-						// TODO: real pixels.
-						if(allocated_pointer_) {
-							for(int c = 0; c < next_event - window; c++) {
-//								pixel_pointer_[0] = uint16_t(0xfff ^ (window + c));
-
-//								++pixel_pointer_;
-
-								// Hard-coded here: 1bpp, pixel mode.
-								const uint8_t pixels[2] = { ram_[line_data_pointer_[0]], ram_[line_data_pointer_[0]+1] };
-								line_data_pointer_[0] += 2;
-
-								pixel_pointer_[0] = (pixels[0] & 0x80) ? 0xffff : 0x0000;
-								pixel_pointer_[1] = (pixels[0] & 0x40) ? 0xffff : 0x0000;
-								pixel_pointer_[2] = (pixels[0] & 0x20) ? 0xffff : 0x0000;
-								pixel_pointer_[3] = (pixels[0] & 0x10) ? 0xffff : 0x0000;
-								pixel_pointer_[4] = (pixels[0] & 0x08) ? 0xffff : 0x0000;
-								pixel_pointer_[5] = (pixels[0] & 0x04) ? 0xffff : 0x0000;
-								pixel_pointer_[6] = (pixels[0] & 0x02) ? 0xffff : 0x0000;
-								pixel_pointer_[7] = (pixels[0] & 0x01) ? 0xffff : 0x0000;
-								pixel_pointer_[8] = (pixels[1] & 0x80) ? 0xffff : 0x0000;
-								pixel_pointer_[9] = (pixels[1] & 0x40) ? 0xffff : 0x0000;
-								pixel_pointer_[10] = (pixels[1] & 0x20) ? 0xffff : 0x0000;
-								pixel_pointer_[11] = (pixels[1] & 0x10) ? 0xffff : 0x0000;
-								pixel_pointer_[12] = (pixels[1] & 0x08) ? 0xffff : 0x0000;
-								pixel_pointer_[13] = (pixels[1] & 0x04) ? 0xffff : 0x0000;
-								pixel_pointer_[14] = (pixels[1] & 0x02) ? 0xffff : 0x0000;
-								pixel_pointer_[15] = (pixels[1] & 0x01) ? 0xffff : 0x0000;
-								pixel_pointer_ += 16;
-
-								// TODO: possibly flush here?
+						int columns_remaining = next_event - window;
+						while(columns_remaining) {
+							if(!allocated_pointer_) {
+								flush_pixels();
+								pixel_pointer_ = allocated_pointer_ = reinterpret_cast<uint16_t *>(crt_.begin_data(allocation_size));
 							}
-						} else {
-							pixel_pointer_ += next_event - window;
-						}
 
-						pixel_duration_ += next_event - window;
-						if(pixel_pointer_ - allocated_pointer_ == allocation_size) {
-							flush_pixels();
+							if(allocated_pointer_) {
+								const int output_duration = std::min(columns_remaining, int(allocated_pointer_ + allocation_size - pixel_pointer_) / column_size_);
+
+								switch(mode_) {
+									default:
+									case Mode::Pixel:
+										DispatchBpp(output_pixel);
+									break;
+								}
+
+								pixel_pointer_ += output_duration * column_size_;
+								pixel_duration_ += output_duration;
+								if(pixel_pointer_ - allocated_pointer_ == allocation_size) {
+									flush_pixels();
+								}
+								columns_remaining -= output_duration;
+							} else {
+								// Advance pixel pointer upwards, so as to be able to supply something
+								// convincing to the CRT as to the number of samples that would have
+								// been provided, and skip asking for further allocations for now.
+								pixel_pointer_ += columns_remaining * column_size_;
+								pixel_duration_ += columns_remaining;
+								columns_remaining = 0;
+							}
 						}
+#undef DispatchBpp
 					}
 
 					window = next_event;
@@ -290,3 +312,68 @@ void Nick::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
 Outputs::Display::ScanStatus Nick::get_scaled_scan_status() const {
 	return crt_.get_scaled_scan_status();
 }
+
+// MARK: - Specific pixel outputters.
+
+template <int bpp> void Nick::output_pixel(uint16_t *target, int columns) {
+	for(int c = 0; c < columns; c++) {
+		const uint8_t pixels[2] = { ram_[line_data_pointer_[0]], ram_[line_data_pointer_[0]+1] };
+		line_data_pointer_[0] += 2;
+
+		switch(bpp) {
+			default:
+			case 1:
+				target[0] = palette_[(pixels[0] & 0x80) >> 7];
+				target[1] = palette_[(pixels[0] & 0x40) >> 6];
+				target[2] = palette_[(pixels[0] & 0x20) >> 5];
+				target[3] = palette_[(pixels[0] & 0x10) >> 4];
+				target[4] = palette_[(pixels[0] & 0x08) >> 3];
+				target[5] = palette_[(pixels[0] & 0x04) >> 2];
+				target[6] = palette_[(pixels[0] & 0x02) >> 1];
+				target[7] = palette_[(pixels[0] & 0x01) >> 0];
+
+				target[8] = palette_[(pixels[1] & 0x80) >> 7];
+				target[9] = palette_[(pixels[1] & 0x40) >> 6];
+				target[10] = palette_[(pixels[1] & 0x20) >> 5];
+				target[11] = palette_[(pixels[1] & 0x10) >> 4];
+				target[12] = palette_[(pixels[1] & 0x08) >> 3];
+				target[13] = palette_[(pixels[1] & 0x04) >> 2];
+				target[14] = palette_[(pixels[1] & 0x02) >> 1];
+				target[15] = palette_[(pixels[1] & 0x01) >> 0];
+
+				target += 16;
+			break;
+
+			case 2:
+				target[0] = palette_[((pixels[0] & 0x80) >> 6) | ((pixels[0] & 0x08) >> 3)];
+				target[1] = palette_[((pixels[0] & 0x40) >> 5) | ((pixels[0] & 0x04) >> 2)];
+				target[2] = palette_[((pixels[0] & 0x20) >> 4) | ((pixels[0] & 0x02) >> 1)];
+				target[3] = palette_[((pixels[0] & 0x10) >> 3) | ((pixels[0] & 0x01) >> 0)];
+
+				target[4] = palette_[((pixels[1] & 0x80) >> 6) | ((pixels[1] & 0x08) >> 3)];
+				target[5] = palette_[((pixels[1] & 0x40) >> 5) | ((pixels[1] & 0x04) >> 2)];
+				target[6] = palette_[((pixels[1] & 0x20) >> 4) | ((pixels[1] & 0x02) >> 1)];
+				target[7] = palette_[((pixels[1] & 0x10) >> 3) | ((pixels[1] & 0x01) >> 0)];
+
+				target += 8;
+			break;
+
+			case 4:
+				target[0] = palette_[((pixels[0] & 0x80) >> 4) | ((pixels[0] & 0x20) >> 3) | ((pixels[0] & 0x08) >> 2) | ((pixels[0] & 0x02) >> 1)];
+				target[1] = palette_[((pixels[0] & 0x40) >> 3) | ((pixels[0] & 0x10) >> 2) | ((pixels[0] & 0x04) >> 1) | ((pixels[0] & 0x01) >> 0)];
+
+				target[2] = palette_[((pixels[1] & 0x80) >> 4) | ((pixels[1] & 0x20) >> 3) | ((pixels[1] & 0x08) >> 2) | ((pixels[1] & 0x02) >> 1)];
+				target[3] = palette_[((pixels[1] & 0x40) >> 3) | ((pixels[1] & 0x10) >> 2) | ((pixels[1] & 0x04) >> 1) | ((pixels[1] & 0x01) >> 0)];
+
+				target += 4;
+			break;
+
+			case 8:
+				target[0] = mapped_colour(pixels[0]);
+				target[1] = mapped_colour(pixels[1]);
+				target += 2;
+			break;
+		}
+	}
+}
+
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 424ba8b1c..be6cabf23 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -62,16 +62,25 @@ class Nick {
 			Pixels,
 			Blank,
 		} state_ = State::Sync;
+		int bpp_ = 0;
+		int column_size_ = 0;
 
 		// An accumulator for border output regions.
 		int border_duration_ = 0;
 		void flush_border();
 
 		// The destination for new pixels.
-		static constexpr int allocation_size = 800; // TODO: pick an appropriate length once the serialiser is working correctly.
+		static constexpr int allocation_size = 80;
+		static_assert((allocation_size % 16) == 0, "Allocation size must be a multiple of 16");
 		uint16_t *pixel_pointer_ = nullptr, *allocated_pointer_ = nullptr;
 		int pixel_duration_ = 0;
 		void flush_pixels();
+
+		// Current palette.
+		uint16_t palette_[16]{};
+
+		// Specific outputters.
+		template <int bpp> void output_pixel(uint16_t *target, int columns);
 };
 
 

From 7161783a4fd7691513c853b377a6cb81d9042af0 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 16 Jun 2021 21:16:26 -0400
Subject: [PATCH 026/117] Adds lpixel output.

---
 Machines/Enterprise/Nick.cpp | 77 +++++++++++++++++++++++-------------
 Machines/Enterprise/Nick.hpp |  2 +-
 2 files changed, 50 insertions(+), 29 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 6f6de05ce..626c47c97 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -127,7 +127,7 @@ void Nick::run_for(HalfCycles duration) {
 //					case Mode::CH64:
 //					case Mode::CH128:
 //					case Mode::CH256:
-//					case Mode::LPixel:	column_size_ = 8 / bpp_;	break;
+					case Mode::LPixel:	column_size_ = 8 / bpp_;	break;
 //					case Mode::Attr:	column_size_ = 8;			break;
 				}
 
@@ -206,12 +206,15 @@ void Nick::run_for(HalfCycles duration) {
 #define DispatchBpp(func) \
 	switch(bpp_) {	\
 		default:	\
-		case 1: func<1>(pixel_pointer_, output_duration);	break;	\
-		case 2: func<2>(pixel_pointer_, output_duration);	break;	\
-		case 4: func<4>(pixel_pointer_, output_duration);	break;	\
-		case 8: func<8>(pixel_pointer_, output_duration);	break;	\
+		case 1: func(1)(pixel_pointer_, output_duration);	break;	\
+		case 2: func(2)(pixel_pointer_, output_duration);	break;	\
+		case 4: func(4)(pixel_pointer_, output_duration);	break;	\
+		case 8: func(8)(pixel_pointer_, output_duration);	break;	\
 	}
 
+#define pixel(x) output_pixel<x, false>
+#define lpixel(x) output_pixel<x, true>
+
 						int columns_remaining = next_event - window;
 						while(columns_remaining) {
 							if(!allocated_pointer_) {
@@ -224,9 +227,8 @@ void Nick::run_for(HalfCycles duration) {
 
 								switch(mode_) {
 									default:
-									case Mode::Pixel:
-										DispatchBpp(output_pixel);
-									break;
+									case Mode::Pixel:	DispatchBpp(pixel);		break;
+									case Mode::LPixel:	DispatchBpp(lpixel);	break;
 								}
 
 								pixel_pointer_ += output_duration * column_size_;
@@ -244,6 +246,8 @@ void Nick::run_for(HalfCycles duration) {
 								columns_remaining = 0;
 							}
 						}
+#undef pixel
+#undef lpixel
 #undef DispatchBpp
 					}
 
@@ -315,7 +319,7 @@ Outputs::Display::ScanStatus Nick::get_scaled_scan_status() const {
 
 // MARK: - Specific pixel outputters.
 
-template <int bpp> void Nick::output_pixel(uint16_t *target, int columns) {
+template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int columns) {
 	for(int c = 0; c < columns; c++) {
 		const uint8_t pixels[2] = { ram_[line_data_pointer_[0]], ram_[line_data_pointer_[0]+1] };
 		line_data_pointer_[0] += 2;
@@ -332,16 +336,20 @@ template <int bpp> void Nick::output_pixel(uint16_t *target, int columns) {
 				target[6] = palette_[(pixels[0] & 0x02) >> 1];
 				target[7] = palette_[(pixels[0] & 0x01) >> 0];
 
-				target[8] = palette_[(pixels[1] & 0x80) >> 7];
-				target[9] = palette_[(pixels[1] & 0x40) >> 6];
-				target[10] = palette_[(pixels[1] & 0x20) >> 5];
-				target[11] = palette_[(pixels[1] & 0x10) >> 4];
-				target[12] = palette_[(pixels[1] & 0x08) >> 3];
-				target[13] = palette_[(pixels[1] & 0x04) >> 2];
-				target[14] = palette_[(pixels[1] & 0x02) >> 1];
-				target[15] = palette_[(pixels[1] & 0x01) >> 0];
+				if(!is_lpixel) {
+					target[8] = palette_[(pixels[1] & 0x80) >> 7];
+					target[9] = palette_[(pixels[1] & 0x40) >> 6];
+					target[10] = palette_[(pixels[1] & 0x20) >> 5];
+					target[11] = palette_[(pixels[1] & 0x10) >> 4];
+					target[12] = palette_[(pixels[1] & 0x08) >> 3];
+					target[13] = palette_[(pixels[1] & 0x04) >> 2];
+					target[14] = palette_[(pixels[1] & 0x02) >> 1];
+					target[15] = palette_[(pixels[1] & 0x01) >> 0];
 
-				target += 16;
+					target += 8;
+				}
+
+				target += 8;
 			break;
 
 			case 2:
@@ -350,28 +358,41 @@ template <int bpp> void Nick::output_pixel(uint16_t *target, int columns) {
 				target[2] = palette_[((pixels[0] & 0x20) >> 4) | ((pixels[0] & 0x02) >> 1)];
 				target[3] = palette_[((pixels[0] & 0x10) >> 3) | ((pixels[0] & 0x01) >> 0)];
 
-				target[4] = palette_[((pixels[1] & 0x80) >> 6) | ((pixels[1] & 0x08) >> 3)];
-				target[5] = palette_[((pixels[1] & 0x40) >> 5) | ((pixels[1] & 0x04) >> 2)];
-				target[6] = palette_[((pixels[1] & 0x20) >> 4) | ((pixels[1] & 0x02) >> 1)];
-				target[7] = palette_[((pixels[1] & 0x10) >> 3) | ((pixels[1] & 0x01) >> 0)];
+				if(!is_lpixel) {
+					target[4] = palette_[((pixels[1] & 0x80) >> 6) | ((pixels[1] & 0x08) >> 3)];
+					target[5] = palette_[((pixels[1] & 0x40) >> 5) | ((pixels[1] & 0x04) >> 2)];
+					target[6] = palette_[((pixels[1] & 0x20) >> 4) | ((pixels[1] & 0x02) >> 1)];
+					target[7] = palette_[((pixels[1] & 0x10) >> 3) | ((pixels[1] & 0x01) >> 0)];
 
-				target += 8;
+					target += 4;
+				}
+
+				target += 4;
 			break;
 
 			case 4:
 				target[0] = palette_[((pixels[0] & 0x80) >> 4) | ((pixels[0] & 0x20) >> 3) | ((pixels[0] & 0x08) >> 2) | ((pixels[0] & 0x02) >> 1)];
 				target[1] = palette_[((pixels[0] & 0x40) >> 3) | ((pixels[0] & 0x10) >> 2) | ((pixels[0] & 0x04) >> 1) | ((pixels[0] & 0x01) >> 0)];
 
-				target[2] = palette_[((pixels[1] & 0x80) >> 4) | ((pixels[1] & 0x20) >> 3) | ((pixels[1] & 0x08) >> 2) | ((pixels[1] & 0x02) >> 1)];
-				target[3] = palette_[((pixels[1] & 0x40) >> 3) | ((pixels[1] & 0x10) >> 2) | ((pixels[1] & 0x04) >> 1) | ((pixels[1] & 0x01) >> 0)];
+				if(!is_lpixel) {
+					target[2] = palette_[((pixels[1] & 0x80) >> 4) | ((pixels[1] & 0x20) >> 3) | ((pixels[1] & 0x08) >> 2) | ((pixels[1] & 0x02) >> 1)];
+					target[3] = palette_[((pixels[1] & 0x40) >> 3) | ((pixels[1] & 0x10) >> 2) | ((pixels[1] & 0x04) >> 1) | ((pixels[1] & 0x01) >> 0)];
 
-				target += 4;
+					target += 2;
+				}
+
+				target += 2;
 			break;
 
 			case 8:
 				target[0] = mapped_colour(pixels[0]);
-				target[1] = mapped_colour(pixels[1]);
-				target += 2;
+
+				if(!is_lpixel) {
+					target[1] = mapped_colour(pixels[1]);
+
+					++target;
+				}
+				++target;
 			break;
 		}
 	}
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index be6cabf23..3cf2636ce 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -80,7 +80,7 @@ class Nick {
 		uint16_t palette_[16]{};
 
 		// Specific outputters.
-		template <int bpp> void output_pixel(uint16_t *target, int columns);
+		template <int bpp, bool is_lpixel> void output_pixel(uint16_t *target, int columns);
 };
 
 

From 4414e9671018162a04a1ab08e99daf6a3a4792e9 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 16 Jun 2021 21:42:20 -0400
Subject: [PATCH 027/117] Adds enough text mode for now.

Discovered: a memory fault is being reported at startup.
---
 Machines/Enterprise/Nick.cpp | 75 +++++++++++++++++++++++++++++++-----
 Machines/Enterprise/Nick.hpp |  1 +
 2 files changed, 66 insertions(+), 10 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 626c47c97..5d1ad6633 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -124,9 +124,9 @@ void Nick::run_for(HalfCycles duration) {
 				switch(mode_) {
 					default:
 					case Mode::Pixel:	column_size_ = 16 / bpp_;	break;
-//					case Mode::CH64:
-//					case Mode::CH128:
-//					case Mode::CH256:
+					case Mode::CH64:
+					case Mode::CH128:
+					case Mode::CH256:
 					case Mode::LPixel:	column_size_ = 8 / bpp_;	break;
 //					case Mode::Attr:	column_size_ = 8;			break;
 				}
@@ -214,6 +214,9 @@ void Nick::run_for(HalfCycles duration) {
 
 #define pixel(x) output_pixel<x, false>
 #define lpixel(x) output_pixel<x, true>
+#define ch256(x) output_character<x, 8>
+#define ch128(x) output_character<x, 7>
+#define ch64(x) output_character<x, 6>
 
 						int columns_remaining = next_event - window;
 						while(columns_remaining) {
@@ -229,6 +232,9 @@ void Nick::run_for(HalfCycles duration) {
 									default:
 									case Mode::Pixel:	DispatchBpp(pixel);		break;
 									case Mode::LPixel:	DispatchBpp(lpixel);	break;
+									case Mode::CH256:	DispatchBpp(ch256);		break;
+									case Mode::CH128:	DispatchBpp(ch128);		break;
+									case Mode::CH64:	DispatchBpp(ch64);		break;
 								}
 
 								pixel_pointer_ += output_duration * column_size_;
@@ -245,7 +251,11 @@ void Nick::run_for(HalfCycles duration) {
 								pixel_duration_ += columns_remaining;
 								columns_remaining = 0;
 							}
+
 						}
+#undef ch64
+#undef ch128
+#undef ch256
 #undef pixel
 #undef lpixel
 #undef DispatchBpp
@@ -285,7 +295,16 @@ void Nick::run_for(HalfCycles duration) {
 				}
 			}
 
-			// TODO: should reload line data pointers?
+			// TODO: logic below is very incomplete.
+			switch(mode_) {
+				default: break;
+				case Mode::CH64:
+				case Mode::CH128:
+				case Mode::CH256:
+					line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
+					++line_data_pointer_[1];
+				break;
+			}
 		}
 	}
 }
@@ -320,9 +339,11 @@ Outputs::Display::ScanStatus Nick::get_scaled_scan_status() const {
 // MARK: - Specific pixel outputters.
 
 template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int columns) {
+	static_assert(bpp == 1 || bpp == 2 || bpp == 4 || bpp == 8);
+
 	for(int c = 0; c < columns; c++) {
-		const uint8_t pixels[2] = { ram_[line_data_pointer_[0]], ram_[line_data_pointer_[0]+1] };
-		line_data_pointer_[0] += 2;
+		const uint8_t pixels[2] = { ram_[line_data_pointer_[0]], ram_[(line_data_pointer_[0]+1) & 0xffff] };
+		line_data_pointer_[0] += is_lpixel ? 1 : 2;
 
 		switch(bpp) {
 			default:
@@ -336,7 +357,7 @@ template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int
 				target[6] = palette_[(pixels[0] & 0x02) >> 1];
 				target[7] = palette_[(pixels[0] & 0x01) >> 0];
 
-				if(!is_lpixel) {
+				if constexpr (!is_lpixel) {
 					target[8] = palette_[(pixels[1] & 0x80) >> 7];
 					target[9] = palette_[(pixels[1] & 0x40) >> 6];
 					target[10] = palette_[(pixels[1] & 0x20) >> 5];
@@ -358,7 +379,7 @@ template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int
 				target[2] = palette_[((pixels[0] & 0x20) >> 4) | ((pixels[0] & 0x02) >> 1)];
 				target[3] = palette_[((pixels[0] & 0x10) >> 3) | ((pixels[0] & 0x01) >> 0)];
 
-				if(!is_lpixel) {
+				if constexpr (!is_lpixel) {
 					target[4] = palette_[((pixels[1] & 0x80) >> 6) | ((pixels[1] & 0x08) >> 3)];
 					target[5] = palette_[((pixels[1] & 0x40) >> 5) | ((pixels[1] & 0x04) >> 2)];
 					target[6] = palette_[((pixels[1] & 0x20) >> 4) | ((pixels[1] & 0x02) >> 1)];
@@ -374,7 +395,7 @@ template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int
 				target[0] = palette_[((pixels[0] & 0x80) >> 4) | ((pixels[0] & 0x20) >> 3) | ((pixels[0] & 0x08) >> 2) | ((pixels[0] & 0x02) >> 1)];
 				target[1] = palette_[((pixels[0] & 0x40) >> 3) | ((pixels[0] & 0x10) >> 2) | ((pixels[0] & 0x04) >> 1) | ((pixels[0] & 0x01) >> 0)];
 
-				if(!is_lpixel) {
+				if constexpr (!is_lpixel) {
 					target[2] = palette_[((pixels[1] & 0x80) >> 4) | ((pixels[1] & 0x20) >> 3) | ((pixels[1] & 0x08) >> 2) | ((pixels[1] & 0x02) >> 1)];
 					target[3] = palette_[((pixels[1] & 0x40) >> 3) | ((pixels[1] & 0x10) >> 2) | ((pixels[1] & 0x04) >> 1) | ((pixels[1] & 0x01) >> 0)];
 
@@ -387,7 +408,7 @@ template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int
 			case 8:
 				target[0] = mapped_colour(pixels[0]);
 
-				if(!is_lpixel) {
+				if constexpr (!is_lpixel) {
 					target[1] = mapped_colour(pixels[1]);
 
 					++target;
@@ -398,3 +419,37 @@ template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int
 	}
 }
 
+template <int bpp, int index_bits> void Nick::output_character(uint16_t *target, int columns) {
+	static_assert(bpp == 1 || bpp == 2 || bpp == 4 || bpp == 8);
+
+	for(int c = 0; c < columns; c++) {
+		const uint8_t character = ram_[line_data_pointer_[0]];
+		++line_data_pointer_[0];
+
+		const uint8_t pixels = ram_[
+			(line_data_pointer_[1] << index_bits) +
+			(character & ((1 << index_bits) - 1))
+		];
+
+		// TODO: below looks repetitious of the above, but I've yet to factor in
+		// ALTINDs and [M/L]SBALTs, so I'll correct for factoring when I've done that.
+
+		switch(bpp) {
+			default:
+				assert(false);
+			break;
+
+			case 1:
+				target[0] = palette_[(pixels & 0x80) >> 7];
+				target[1] = palette_[(pixels & 0x40) >> 6];
+				target[2] = palette_[(pixels & 0x20) >> 5];
+				target[3] = palette_[(pixels & 0x10) >> 4];
+				target[4] = palette_[(pixels & 0x08) >> 3];
+				target[5] = palette_[(pixels & 0x04) >> 2];
+				target[6] = palette_[(pixels & 0x02) >> 1];
+				target[7] = palette_[(pixels & 0x01) >> 0];
+				target += 8;
+			break;
+		}
+	}
+}
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 3cf2636ce..9fc854c75 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -81,6 +81,7 @@ class Nick {
 
 		// Specific outputters.
 		template <int bpp, bool is_lpixel> void output_pixel(uint16_t *target, int columns);
+		template <int bpp, int index_bits> void output_character(uint16_t *target, int columns);
 };
 
 

From c331d1542941c2077ef5dc3b58b420931a8f5d97 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 16 Jun 2021 22:25:00 -0400
Subject: [PATCH 028/117] Makes space to allow for 64kb EXOS ROMs.

I think some of the later ROMs have a more thorough memory test, which might provide better detail on whatever's going on here.
---
 Machines/Enterprise/Enterprise.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index c9a0151ab..79a65293e 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -76,6 +76,7 @@ class ConcreteMachine:
 			}
 
 			const auto &exos = roms.find(exos_name)->second;
+			exos_.fill(0xff);
 			memcpy(exos_.data(), exos.data(), std::min(exos_.size(), exos.size()));
 
 			// Take a reasonable guess at the initial memory configuration:
@@ -192,7 +193,7 @@ class ConcreteMachine:
 	private:
 		// MARK: - Memory layout
 		std::array<uint8_t, 256 * 1024> ram_;
-		std::array<uint8_t, 32 * 1024> exos_;
+		std::array<uint8_t, 64 * 1024> exos_;
 		const uint8_t min_ram_slot_ = 0xff - 3;
 
 		const uint8_t *read_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
@@ -202,7 +203,7 @@ class ConcreteMachine:
 		template <size_t slot> void page(uint8_t offset) {
 			pages_[slot] = offset;
 
-			if(offset < 2) {
+			if(offset < exos_.size() / 0x4000) {
 				page<slot>(&exos_[offset * 0x4000], nullptr);
 				return;
 			}

From 0c3e9dca28f6bdb5f086e67fc69f0254de78f91d Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 17 Jun 2021 20:47:56 -0400
Subject: [PATCH 029/117] Adds some basic keyboard inputs.

I think the next thing required is interrupts though.
---
 Machines/Enterprise/Enterprise.cpp            | 34 +++++++++--
 Machines/Enterprise/Keyboard.cpp              | 47 ++++++++++++++
 Machines/Enterprise/Keyboard.hpp              | 61 +++++++++++++++++++
 .../Clock Signal.xcodeproj/project.pbxproj    |  8 +++
 4 files changed, 146 insertions(+), 4 deletions(-)
 create mode 100644 Machines/Enterprise/Keyboard.cpp
 create mode 100644 Machines/Enterprise/Keyboard.hpp

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 79a65293e..bdb60546c 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -8,6 +8,7 @@
 
 #include "Enterprise.hpp"
 
+#include "Keyboard.hpp"
 #include "Nick.hpp"
 
 #include "../MachineTypes.hpp"
@@ -59,6 +60,7 @@ namespace Enterprise {
 class ConcreteMachine:
 	public CPU::Z80::BusHandler,
 	public Machine,
+	public MachineTypes::MappedKeyboardMachine,
 	public MachineTypes::ScanProducer,
 	public MachineTypes::TimedMachine {
 	public:
@@ -120,8 +122,11 @@ class ConcreteMachine:
 							*cycle.value = 0xff;
 						break;
 						case 0xb5:
-							printf("TODO: Keyboard/joystick input\n");
-							*cycle.value = 0xff;
+							if(active_key_line_ < key_lines_.size()) {
+								*cycle.value = key_lines_[active_key_line_];
+							} else {
+								*cycle.value = 0xff;
+							}
 						break;
 					}
 				break;
@@ -156,7 +161,8 @@ class ConcreteMachine:
 							printf("TODO: interrupt enable/reset write %02x\n", *cycle.value);
 						break;
 						case 0xb5:
-							printf("TODO: Keyboard/etc %02x\n", *cycle.value);
+							active_key_line_ = *cycle.value & 0xf;
+							// TODO: printer strobe, type sound, REM switches.
 						break;
 						case 0xb6:
 							printf("TODO: printer output %02x\n", *cycle.value);
@@ -194,7 +200,7 @@ class ConcreteMachine:
 		// MARK: - Memory layout
 		std::array<uint8_t, 256 * 1024> ram_;
 		std::array<uint8_t, 64 * 1024> exos_;
-		const uint8_t min_ram_slot_ = 0xff - 3;
+		const uint8_t min_ram_slot_ = 0xff - 16 + 1;
 
 		const uint8_t *read_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
 		uint8_t *write_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
@@ -241,6 +247,26 @@ class ConcreteMachine:
 			z80_.run_for(cycles);
 		}
 
+		// MARK: - KeyboardMachine
+		Enterprise::KeyboardMapper keyboard_mapper_;
+		KeyboardMapper *get_keyboard_mapper() final {
+			return &keyboard_mapper_;
+		}
+
+		uint8_t active_key_line_ = 0;
+		std::array<uint8_t, 10> key_lines_;
+		void set_key_state(uint16_t key, bool is_pressed) final {
+			if(is_pressed) {
+				key_lines_[key >> 8] &= ~uint8_t(key);
+			} else {
+				key_lines_[key >> 8] |= uint8_t(key);
+			}
+		}
+
+		void clear_all_keys() final {
+			key_lines_.fill(0xff);
+		}
+
 		// MARK: - Chips.
 		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
 		JustInTimeActor<Nick, HalfCycles, 444923, 125000> nick_;
diff --git a/Machines/Enterprise/Keyboard.cpp b/Machines/Enterprise/Keyboard.cpp
new file mode 100644
index 000000000..bf0d582e1
--- /dev/null
+++ b/Machines/Enterprise/Keyboard.cpp
@@ -0,0 +1,47 @@
+//
+//  Keyboard.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 17/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#include "Keyboard.hpp"
+
+using namespace Enterprise;
+
+uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
+#define BIND(source, dest)	case Inputs::Keyboard::Key::source:	return uint16_t(Key::dest)
+	switch(key) {
+		default: break;
+
+		BIND(k1, k1);	BIND(k2, k2);	BIND(k3, k3);	BIND(k4, k4);	BIND(k5, k5);
+		BIND(k6, k6);	BIND(k7, k7);	BIND(k8, k8);	BIND(k9, k9);	BIND(k0, k0);
+
+		BIND(Q, Q);	BIND(W, W);	BIND(E, E);	BIND(R, R);	BIND(T, T);
+		BIND(Y, Y);	BIND(U, U);	BIND(I, I);	BIND(O, O);	BIND(P, P);
+
+		BIND(A, A);	BIND(S, S);	BIND(D, D);	BIND(F, F);	BIND(G, G);
+		BIND(H, H);	BIND(J, J);	BIND(K, K);	BIND(L, L);
+
+		BIND(Z, Z);	BIND(X, X);	BIND(C, C);	BIND(V, V);
+		BIND(B, B);	BIND(N, N);	BIND(M, M);
+
+		BIND(Space, Space);	BIND(Enter, Enter);
+
+		BIND(LeftShift, LeftShift);
+		BIND(RightShift, RightShift);
+		BIND(LeftOption, Option);
+		BIND(RightOption, Option);
+		BIND(LeftControl, Control);
+		BIND(RightControl, Control);
+
+		BIND(Left, Left);
+		BIND(Right, Right);
+		BIND(Up, Up);
+		BIND(Down, Down);
+	}
+#undef BIND
+
+	return MachineTypes::MappedKeyboardMachine::KeyNotMapped;
+}
diff --git a/Machines/Enterprise/Keyboard.hpp b/Machines/Enterprise/Keyboard.hpp
new file mode 100644
index 000000000..6ff2e83dc
--- /dev/null
+++ b/Machines/Enterprise/Keyboard.hpp
@@ -0,0 +1,61 @@
+//
+//  Keyboard.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 17/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#ifndef Machines_Enterprise_Keyboard_hpp
+#define Machines_Enterprise_Keyboard_hpp
+
+#include "../KeyboardMachine.hpp"
+
+namespace Enterprise {
+
+#define KeyCode(line, mask)	(line << 8) | mask
+
+enum class Key: uint16_t {
+	N		= 0x0000 | 0x01,	BackSlash	= 0x0000 | 0x02,	B		= 0x0000 | 0x04,	C			= 0x0000 | 0x08,
+	V		= 0x0000 | 0x10,	X 			= 0x0000 | 0x20,	Z		= 0x0000 | 0x40,	LeftShift	= 0x0000 | 0x80,
+
+	H		= 0x0100 | 0x01,	Lock		= 0x0100 | 0x02,	G		= 0x0100 | 0x04,	D			= 0x0100 | 0x08,
+	F		= 0x0100 | 0x10,	S			= 0x0100 | 0x20,	A		= 0x0100 | 0x40,	Control		= 0x0100 | 0x80,
+
+	U		= 0x0200 | 0x01,	Q			= 0x0200 | 0x02,	Y		= 0x0200 | 0x04,	R			= 0x0200 | 0x08,
+	T		= 0x0200 | 0x10,	E			= 0x0200 | 0x20,	W		= 0x0200 | 0x40,	Tab			= 0x0200 | 0x80,
+
+	k7		= 0x0300 | 0x01,	k1			= 0x0300 | 0x02,	k6		= 0x0300 | 0x04,	k4			= 0x0300 | 0x08,
+	k5		= 0x0300 | 0x10,	k3			= 0x0300 | 0x20,	k2		= 0x0300 | 0x40,	Escape		= 0x0300 | 0x80,
+
+	F4		= 0x0400 | 0x01,	F8			= 0x0400 | 0x02,	F3		= 0x0400 | 0x04,	F6			= 0x0400 | 0x08,
+	F5		= 0x0400 | 0x10,	F7			= 0x0400 | 0x20,	F2		= 0x0400 | 0x40,	F1			= 0x0400 | 0x80,
+
+	k8		= 0x0500 | 0x01,									k9		= 0x0500 | 0x04,	Hyphen		= 0x0500 | 0x08,
+	k0		= 0x0500 | 0x10,	Tilde		= 0x0500 | 0x20,	Erase	= 0x0500 | 0x40,
+
+	J		= 0x0600 | 0x01,									K		= 0x0600 | 0x04,	SemiColon	= 0x0600 | 0x08,
+	L		= 0x0600 | 0x10,	Colon		= 0x0600 | 0x20,	CloseSquareBracket		= 0x0600 | 0x40,
+
+	Stop	= 0x0700 | 0x01,	Down		= 0x0700 | 0x02,	Right	= 0x0700 | 0x04,	Up			= 0x0700 | 0x08,
+	Hold	= 0x0700 | 0x10,	Left		= 0x0700 | 0x20,	Enter	= 0x0700 | 0x40,	Option		= 0x0700 | 0x80,
+
+	M		= 0x0800 | 0x01,	Delete		= 0x0800 | 0x02,	Comma	= 0x0800 | 0x04,
+	ForwardSlash	= 0x0800 | 0x08,
+	FullStop		= 0x0800 | 0x10,
+								RightShift	= 0x0800 | 0x20,	Space	= 0x0800 | 0x40,	Insert		= 0x0800 | 0x80,
+
+	I		= 0x0900 | 0x01,									O		= 0x0900 | 0x04,	At			= 0x0900 | 0x08,
+	P		= 0x0900 | 0x10,
+	OpenSquareBracket		= 0x0900 | 0x20
+};
+
+#undef KeyCode
+
+struct KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
+	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const final;
+};
+
+}
+
+#endif /* Keyboard_hpp */
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index f672c30ac..1dbe4c55c 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -23,6 +23,8 @@
 		4B051CA926781D6500CA44E8 /* StaticAnalyser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CA726781D6500CA44E8 /* StaticAnalyser.cpp */; };
 		4B051CAC26783E2000CA44E8 /* Nick.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAA26783E2000CA44E8 /* Nick.cpp */; };
 		4B051CAD26783E2000CA44E8 /* Nick.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAA26783E2000CA44E8 /* Nick.cpp */; };
+		4B051CB0267C1CA200CA44E8 /* Keyboard.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */; };
+		4B051CB1267C1CA200CA44E8 /* Keyboard.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */; };
 		4B05401E219D1618001BF69C /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B05401D219D1618001BF69C /* ScanTarget.cpp */; };
 		4B05401F219D1618001BF69C /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B05401D219D1618001BF69C /* ScanTarget.cpp */; };
 		4B055A7A1FAE78A00060FFFF /* SDL2.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 4B055A771FAE78210060FFFF /* SDL2.framework */; };
@@ -1041,6 +1043,8 @@
 		4B051CA726781D6500CA44E8 /* StaticAnalyser.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = StaticAnalyser.cpp; sourceTree = "<group>"; };
 		4B051CAA26783E2000CA44E8 /* Nick.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = Nick.cpp; sourceTree = "<group>"; };
 		4B051CAB26783E2000CA44E8 /* Nick.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Nick.hpp; sourceTree = "<group>"; };
+		4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = Keyboard.cpp; sourceTree = "<group>"; };
+		4B051CAF267C1CA200CA44E8 /* Keyboard.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Keyboard.hpp; sourceTree = "<group>"; };
 		4B05401D219D1618001BF69C /* ScanTarget.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = ScanTarget.cpp; sourceTree = "<group>"; };
 		4B055A6A1FAE763F0060FFFF /* Clock Signal Kiosk */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = "Clock Signal Kiosk"; sourceTree = BUILT_PRODUCTS_DIR; };
 		4B055A771FAE78210060FFFF /* SDL2.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = SDL2.framework; path = ../../../../Library/Frameworks/SDL2.framework; sourceTree = SOURCE_ROOT; };
@@ -2107,8 +2111,10 @@
 			isa = PBXGroup;
 			children = (
 				4B051CA12676F52200CA44E8 /* Enterprise.cpp */,
+				4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */,
 				4B051CAA26783E2000CA44E8 /* Nick.cpp */,
 				4B051CA02676F52200CA44E8 /* Enterprise.hpp */,
+				4B051CAF267C1CA200CA44E8 /* Keyboard.hpp */,
 				4B051CAB26783E2000CA44E8 /* Nick.hpp */,
 			);
 			path = Enterprise;
@@ -5377,6 +5383,7 @@
 				4B051C912669C90B00CA44E8 /* ROMCatalogue.cpp in Sources */,
 				4B055AB91FAE86170060FFFF /* Acorn.cpp in Sources */,
 				4B302185208A550100773308 /* DiskII.cpp in Sources */,
+				4B051CB1267C1CA200CA44E8 /* Keyboard.cpp in Sources */,
 				4B0F1BB32602645900B85C66 /* StaticAnalyser.cpp in Sources */,
 				4B055A931FAE85B50060FFFF /* BinaryDump.cpp in Sources */,
 				4B89452D201967B4007DE474 /* Tape.cpp in Sources */,
@@ -5537,6 +5544,7 @@
 				4B5FADBA1DE3151600AEC565 /* FileHolder.cpp in Sources */,
 				4B643F3A1D77AD1900D431D6 /* CSStaticAnalyser.mm in Sources */,
 				4B622AE5222E0AD5008B59F2 /* DisplayMetrics.cpp in Sources */,
+				4B051CB0267C1CA200CA44E8 /* Keyboard.cpp in Sources */,
 				4B1497881EE4A1DA00CE2596 /* ZX80O81P.cpp in Sources */,
 				4B894520201967B4007DE474 /* StaticAnalyser.cpp in Sources */,
 				4BB4BFAD22A33DE50069048D /* DriveSpeedAccumulator.cpp in Sources */,

From 2fd8a8aa66bbf4e51546d719ddb91fea576e4aba Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 17 Jun 2021 22:30:24 -0400
Subject: [PATCH 030/117] Begins addition of interrupt feedback from Nick.

Also fixes clock rate. Though clearly get_next_sequence_point isn't quite right yet.
---
 Machines/Enterprise/Enterprise.cpp | 16 +++++++++++++++-
 Machines/Enterprise/Nick.cpp       | 23 ++++++++++++++++++++++-
 Machines/Enterprise/Nick.hpp       | 13 ++++++++++++-
 3 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index bdb60546c..f07f99352 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -94,13 +94,26 @@ class ConcreteMachine:
 			page<3>(0x00);
 		}
 
+		int halves = 0;
+
 		// MARK: - Z80::BusHandler.
 		forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
 			using PartialMachineCycle = CPU::Z80::PartialMachineCycle;
 			const uint16_t address = cycle.address ? *cycle.address : 0x0000;
 
 			// TODO: possibly apply an access penalty.
-			nick_ += cycle.length;
+
+
+			halves += cycle.length.as<int>();
+			if(nick_ += cycle.length) {
+				const auto nick = nick_.last_valid();
+				const bool nick_interrupt_line = nick->get_interrupt_line();
+				if(nick_interrupt_line && !previous_nick_interrupt_line_) {
+					printf("Interrupt after %d\n", halves + nick_.last_sequence_point_overrun().as<int>());
+					halves = - nick_.last_sequence_point_overrun().as<int>();
+				}
+				previous_nick_interrupt_line_ = nick_interrupt_line;
+			}
 
 			switch(cycle.operation) {
 				default: break;
@@ -270,6 +283,7 @@ class ConcreteMachine:
 		// MARK: - Chips.
 		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
 		JustInTimeActor<Nick, HalfCycles, 444923, 125000> nick_;
+		bool previous_nick_interrupt_line_ = false;
 		// Cf. timing guesses above.
 };
 
diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 5d1ad6633..ff87820a3 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -82,7 +82,7 @@ uint8_t Nick::read([[maybe_unused]] uint16_t address) {
 	return 0xff;
 }
 
-void Nick::run_for(HalfCycles duration) {
+void Nick::run_for(Cycles duration) {
 	constexpr int line_length = 912;
 
 	int clocks_remaining = duration.as<int>();
@@ -112,8 +112,13 @@ void Nick::run_for(HalfCycles duration) {
 				++fetch_spot;
 			}
 
+			// TODO: when exactly does the interrupt output change? Am I a window too late? Or two too early?
+
 			// Special: set mode as soon as it's known. It'll be needed at the end of HSYNC.
 			if(window < 2 && fetch_spot >= 2) {
+				// Set the new interrupt line output.
+				interrupt_line_ = line_parameters_[1] & 0x80;
+
 				// Determine the margins.
 				left_margin_ = line_parameters_[2] & 0x3f;
 				right_margin_ = line_parameters_[3] & 0x3f;
@@ -326,6 +331,22 @@ void Nick::flush_pixels() {
 	allocated_pointer_ = nullptr;
 }
 
+// MARK: - Sequence points.
+
+Cycles Nick::get_next_sequence_point() {
+	// TODO: the below is incorrect; unit test and correct.
+	// Changing to e.g. Cycles(1) reveals the relevant discrepancy.
+//	return Cycles(1);
+
+	// Any mode line may cause a change in the interrupt output, so as a first blush
+	// just always report the time until the end of the mode line.
+	if(lines_remaining_ || horizontal_counter_ >= 2) {
+		return Cycles(2 + (912 - horizontal_counter_) + (0xff - lines_remaining_) * 912);
+	} else {
+		return Cycles(2 - horizontal_counter_);
+	}
+}
+
 // MARK: - CRT passthroughs.
 
 void Nick::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 9fc854c75..8926a0252 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -22,11 +22,21 @@ class Nick {
 		void write(uint16_t address, uint8_t value);
 		uint8_t read(uint16_t address);
 
-		void run_for(HalfCycles);
+		void run_for(Cycles);
 
 		void set_scan_target(Outputs::Display::ScanTarget *scan_target);
 		Outputs::Display::ScanStatus get_scaled_scan_status() const;
 
+		Cycles get_next_sequence_point();
+
+		/*!
+			@returns The current state of the interrupt line — @c true for active;
+				@c false for inactive.
+		*/
+		inline bool get_interrupt_line() {
+			return interrupt_line_;
+		}
+
 	private:
 		Outputs::CRT::CRT crt_;
 		const uint8_t *const ram_;
@@ -64,6 +74,7 @@ class Nick {
 		} state_ = State::Sync;
 		int bpp_ = 0;
 		int column_size_ = 0;
+		bool interrupt_line_ = true;
 
 		// An accumulator for border output regions.
 		int border_duration_ = 0;

From 311ddfb05aa0816ee1e41278a7ed4b654a6790ab Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 17 Jun 2021 22:34:52 -0400
Subject: [PATCH 031/117] Add note to self for tomorrow.

---
 Machines/Enterprise/Enterprise.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index f07f99352..5b29c0979 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -108,6 +108,7 @@ class ConcreteMachine:
 			if(nick_ += cycle.length) {
 				const auto nick = nick_.last_valid();
 				const bool nick_interrupt_line = nick->get_interrupt_line();
+				// TEMPORARY. The below should print a bunch of numbers like 15988 on the Enterprise splash screen.
 				if(nick_interrupt_line && !previous_nick_interrupt_line_) {
 					printf("Interrupt after %d\n", halves + nick_.last_sequence_point_overrun().as<int>());
 					halves = - nick_.last_sequence_point_overrun().as<int>();

From fbf1adef051317b7ac5399279a5a636fa34c21b6 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 18 Jun 2021 17:44:17 -0400
Subject: [PATCH 032/117] Introduces unit test and thereby seemingly fixes
 get_next_sequence_point.

There's still improper output in the actual machine though, so maybe something else is afoot?
---
 Machines/Enterprise/Nick.cpp                  | 14 ++--
 Machines/Enterprise/Nick.hpp                  |  2 +-
 .../Clock Signal.xcodeproj/project.pbxproj    | 48 +++++++------
 .../Clock SignalTests/EnterpriseNickTests.mm  | 72 +++++++++++++++++++
 4 files changed, 107 insertions(+), 29 deletions(-)
 create mode 100644 OSBindings/Mac/Clock SignalTests/EnterpriseNickTests.mm

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index ff87820a3..ddaae8324 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -116,6 +116,9 @@ void Nick::run_for(Cycles duration) {
 
 			// Special: set mode as soon as it's known. It'll be needed at the end of HSYNC.
 			if(window < 2 && fetch_spot >= 2) {
+				// Set length of mode line.
+				lines_remaining_ = line_parameters_[0];
+
 				// Set the new interrupt line output.
 				interrupt_line_ = line_parameters_[1] & 0x80;
 
@@ -150,9 +153,6 @@ void Nick::run_for(Cycles duration) {
 			if(fetch_spot == 8) {
 				should_reload_line_parameters_ = false;
 
-				// Set length of mode line.
-				lines_remaining_ = line_parameters_[0];
-
 				// Determine the line data pointers.
 				line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
 				line_data_pointer_[1] = uint16_t(line_parameters_[6] | (line_parameters_[7] << 8));
@@ -338,12 +338,14 @@ Cycles Nick::get_next_sequence_point() {
 	// Changing to e.g. Cycles(1) reveals the relevant discrepancy.
 //	return Cycles(1);
 
+	constexpr int load_point = 2*16;
+
 	// Any mode line may cause a change in the interrupt output, so as a first blush
 	// just always report the time until the end of the mode line.
-	if(lines_remaining_ || horizontal_counter_ >= 2) {
-		return Cycles(2 + (912 - horizontal_counter_) + (0xff - lines_remaining_) * 912);
+	if(lines_remaining_ || horizontal_counter_ >= load_point) {
+		return Cycles(load_point + (912 - horizontal_counter_) + (0xff - lines_remaining_) * 912);
 	} else {
-		return Cycles(2 - horizontal_counter_);
+		return Cycles(load_point - horizontal_counter_);
 	}
 }
 
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 8926a0252..2e4dcf1cb 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -50,7 +50,7 @@ class Nick {
 		int horizontal_counter_ = 0;
 		uint16_t line_parameter_pointer_ = 0x0000;
 		uint8_t line_parameters_[16];
-		bool should_reload_line_parameters_ = false;
+		bool should_reload_line_parameters_ = true;
 		uint16_t line_data_pointer_[2];
 
 		// Current mode line parameters.
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index 1dbe4c55c..127657d64 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -25,6 +25,7 @@
 		4B051CAD26783E2000CA44E8 /* Nick.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAA26783E2000CA44E8 /* Nick.cpp */; };
 		4B051CB0267C1CA200CA44E8 /* Keyboard.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */; };
 		4B051CB1267C1CA200CA44E8 /* Keyboard.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */; };
+		4B051CB3267D3FF800CA44E8 /* EnterpriseNickTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CB2267D3FF800CA44E8 /* EnterpriseNickTests.mm */; };
 		4B05401E219D1618001BF69C /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B05401D219D1618001BF69C /* ScanTarget.cpp */; };
 		4B05401F219D1618001BF69C /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B05401D219D1618001BF69C /* ScanTarget.cpp */; };
 		4B055A7A1FAE78A00060FFFF /* SDL2.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 4B055A771FAE78210060FFFF /* SDL2.framework */; };
@@ -1045,6 +1046,7 @@
 		4B051CAB26783E2000CA44E8 /* Nick.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Nick.hpp; sourceTree = "<group>"; };
 		4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = Keyboard.cpp; sourceTree = "<group>"; };
 		4B051CAF267C1CA200CA44E8 /* Keyboard.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Keyboard.hpp; sourceTree = "<group>"; };
+		4B051CB2267D3FF800CA44E8 /* EnterpriseNickTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = EnterpriseNickTests.mm; sourceTree = "<group>"; };
 		4B05401D219D1618001BF69C /* ScanTarget.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = ScanTarget.cpp; sourceTree = "<group>"; };
 		4B055A6A1FAE763F0060FFFF /* Clock Signal Kiosk */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = "Clock Signal Kiosk"; sourceTree = BUILT_PRODUCTS_DIR; };
 		4B055A771FAE78210060FFFF /* SDL2.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = SDL2.framework; path = ../../../../Library/Frameworks/SDL2.framework; sourceTree = SOURCE_ROOT; };
@@ -4031,12 +4033,8 @@
 		4BB73EB51B587A5100552FC2 /* Clock SignalTests */ = {
 			isa = PBXGroup;
 			children = (
-				4BC9E1ED1D23449A003FCEE4 /* 6502InterruptTests.swift */,
-				4B92EAC91B7C112B00246143 /* 6502TimingTests.swift */,
-				4BC751B11D157E61006C31D9 /* 6522Tests.swift */,
-				4B1E85801D176468001EF87D /* 6532Tests.swift */,
-				4B4F478925367EDC004245B8 /* 65816AddressingTests.swift */,
-				4B8DF5132550D62900F3433C /* 65816kromTests.swift */,
+				4B85322922778E4200F26553 /* Comparative68000.hpp */,
+				4B90467222C6FA31000E2074 /* TestRunner68000.hpp */,
 				4B90467522C6FD6E000E2074 /* 68000ArithmeticTests.mm */,
 				4B9D0C4A22C7D70900DE1AD3 /* 68000BCDTests.mm */,
 				4B90467322C6FADD000E2074 /* 68000BitwiseTests.mm */,
@@ -4045,43 +4043,48 @@
 				4BC5C3DF22C994CC00795658 /* 68000MoveTests.mm */,
 				4B9D0C4E22C7E0CF00DE1AD3 /* 68000RollShiftTests.mm */,
 				4BD388872239E198002D14B5 /* 68000Tests.mm */,
-				4BB73EB61B587A5100552FC2 /* AllSuiteATests.swift */,
 				4B924E981E74D22700B76AF1 /* AtariStaticAnalyserTests.mm */,
 				4BE34437238389E10058E78F /* AtariSTVideoTests.mm */,
-				4B049CDC1DA3C82F00322067 /* BCDTest.swift */,
-				4B3BA0C41D318B44005DD7A7 /* Bridges */,
-				4B3BA0C21D318AEB005DD7A7 /* C1540Tests.swift */,
-				4B85322922778E4200F26553 /* Comparative68000.hpp */,
 				4BB2A9AE1E13367E001A5C23 /* CRCTests.mm */,
-				4BEF6AAB1D35D1C400E73575 /* DPLLTests.swift */,
 				4BFF1D3C2235C3C100838EA1 /* EmuTOSTests.mm */,
-				4BBF49AE1ED2880200AB3669 /* FUSETests.swift */,
+				4B051CB2267D3FF800CA44E8 /* EnterpriseNickTests.mm */,
 				4B8DF4D725465B7500F3433C /* IIgsMemoryMapTests.mm */,
-				4BB73EB81B587A5100552FC2 /* Info.plist */,
-				4B4F477B253530B7004245B8 /* Jeek816Tests.swift */,
-				4B1414611B58888700E04248 /* KlausDormannTests.swift */,
 				4BEE1EBF22B5E236000A26A6 /* MacGCRTests.mm */,
 				4BE90FFC22D5864800FB464D /* MacintoshVideoTests.mm */,
 				4BA91E1C216D85BA00F79557 /* MasterSystemVDPTests.mm */,
 				4B98A0601FFADCDE00ADF63B /* MSXStaticAnalyserTests.mm */,
 				4BC0CB272446BC7B00A79DBB /* OPLTests.mm */,
-				4BD91D762401C2B8007BDC91 /* PatrikRakTests.swift */,
 				4B121F9A1E06293F00BFDA12 /* PCMSegmentEventSourceTests.mm */,
 				4BD4A8CF1E077FD20020D856 /* PCMTrackTests.mm */,
 				4B3F76B825A1635300178AEC /* PowerPCDecoderTests.mm */,
 				4BE76CF822641ED300ACD6FA /* QLTests.mm */,
 				4B8DD3672633B2D400B3C866 /* SpectrumVideoContentionTests.mm */,
-				4B1414631B588A1100E04248 /* Test Binaries */,
-				4B90467222C6FA31000E2074 /* TestRunner68000.hpp */,
 				4B2AF8681E513FC20027EE29 /* TIATests.mm */,
 				4B1D08051E0F7A1100763741 /* TimeTests.mm */,
-				4B14145F1B58885000E04248 /* WolfgangLorenzTests.swift */,
 				4BEE4BD325A26E2B00011BD2 /* x86DecoderTests.mm */,
 				4BDA8234261E8E000021AA19 /* Z80ContentionTests.mm */,
+				4BB73EB81B587A5100552FC2 /* Info.plist */,
+				4BC9E1ED1D23449A003FCEE4 /* 6502InterruptTests.swift */,
+				4B92EAC91B7C112B00246143 /* 6502TimingTests.swift */,
+				4BC751B11D157E61006C31D9 /* 6522Tests.swift */,
+				4B1E85801D176468001EF87D /* 6532Tests.swift */,
+				4B4F478925367EDC004245B8 /* 65816AddressingTests.swift */,
+				4B8DF5132550D62900F3433C /* 65816kromTests.swift */,
+				4BB73EB61B587A5100552FC2 /* AllSuiteATests.swift */,
+				4B049CDC1DA3C82F00322067 /* BCDTest.swift */,
+				4B3BA0C21D318AEB005DD7A7 /* C1540Tests.swift */,
+				4BEF6AAB1D35D1C400E73575 /* DPLLTests.swift */,
+				4BBF49AE1ED2880200AB3669 /* FUSETests.swift */,
+				4B4F477B253530B7004245B8 /* Jeek816Tests.swift */,
+				4B1414611B58888700E04248 /* KlausDormannTests.swift */,
+				4BD91D762401C2B8007BDC91 /* PatrikRakTests.swift */,
+				4B14145F1B58885000E04248 /* WolfgangLorenzTests.swift */,
 				4B08A2741EE35D56008B7065 /* Z80InterruptTests.swift */,
 				4BDDBA981EF3451200347E61 /* Z80MachineCycleTests.swift */,
 				4B01A6871F22F0DB001FD6E3 /* Z80MemptrTests.swift */,
 				4BFCA12A1ECBE7C400AC40C1 /* ZexallTests.swift */,
+				4B3BA0C41D318B44005DD7A7 /* Bridges */,
+				4B1414631B588A1100E04248 /* Test Binaries */,
 			);
 			path = "Clock SignalTests";
 			sourceTree = "<group>";
@@ -5742,6 +5745,7 @@
 				4BFCA12B1ECBE7C400AC40C1 /* ZexallTests.swift in Sources */,
 				4B778F2223A5EDDD0000D260 /* PulseQueuedTape.cpp in Sources */,
 				4B778EF123A5D6B50000D260 /* 9918.cpp in Sources */,
+				4B051CB3267D3FF800CA44E8 /* EnterpriseNickTests.mm in Sources */,
 				4B9D0C4D22C7DA1A00DE1AD3 /* 68000ControlFlowTests.mm in Sources */,
 				4BB2A9AF1E13367E001A5C23 /* CRCTests.mm in Sources */,
 				4B778F5623A5F2AF0000D260 /* CPM.cpp in Sources */,
@@ -6105,7 +6109,7 @@
 				CODE_SIGN_IDENTITY = "-";
 				CODE_SIGN_STYLE = Automatic;
 				DEVELOPMENT_TEAM = DV3346VVUN;
-				ENABLE_HARDENED_RUNTIME = YES;
+				ENABLE_HARDENED_RUNTIME = NO;
 				FRAMEWORK_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(USER_LIBRARY_DIR)/Frameworks",
@@ -6155,7 +6159,7 @@
 				CODE_SIGN_IDENTITY = "-";
 				CODE_SIGN_STYLE = Automatic;
 				DEVELOPMENT_TEAM = DV3346VVUN;
-				ENABLE_HARDENED_RUNTIME = YES;
+				ENABLE_HARDENED_RUNTIME = NO;
 				FRAMEWORK_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(USER_LIBRARY_DIR)/Frameworks",
diff --git a/OSBindings/Mac/Clock SignalTests/EnterpriseNickTests.mm b/OSBindings/Mac/Clock SignalTests/EnterpriseNickTests.mm
new file mode 100644
index 000000000..2799b70ae
--- /dev/null
+++ b/OSBindings/Mac/Clock SignalTests/EnterpriseNickTests.mm	
@@ -0,0 +1,72 @@
+//
+//  EnterpriseNickTests.m
+//  Clock SignalTests
+//
+//  Created by Thomas Harte on 18/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#import <XCTest/XCTest.h>
+
+#include "../../../Machines/Enterprise/Nick.hpp"
+#include <memory>
+
+@interface EnterpriseNickTests : XCTestCase
+@end
+
+@implementation EnterpriseNickTests {
+	std::unique_ptr<Enterprise::Nick> _nick;
+	uint8_t _ram[64*1024];
+	int _totalLines;
+}
+
+- (void)setUp {
+	[super setUp];
+
+	// Create a Nick.
+	_nick = std::make_unique<Enterprise::Nick>(_ram);
+
+	// Add a basic line table of blocks proceeding in length: 1, 2, 3, 4, etc and toggling the interrupt bit.
+	_totalLines = 0;
+	int nextLength = 0;
+	int pointer = 0;
+	uint8_t interruptFlag = 0x80;
+	while(nextLength < 256) {
+		_ram[pointer] = 0x100 - nextLength;
+		_ram[pointer+1] = interruptFlag;
+
+		pointer += 16;
+		++nextLength;
+		interruptFlag ^= 0x80;
+		_totalLines += nextLength;
+	}
+
+	// For now: assume Nick starts at address 0 from creation.
+}
+
+- (void)testInterruptPrediction {
+	// Run for the number of cycles implied by the number of lines.
+	int next_sequence_point = _nick->get_next_sequence_point().as<int>();
+	bool last_interrupt_line = _nick->get_interrupt_line();
+
+	for(int c = 0; c < _totalLines*912; c++) {
+		// Check that interrupt line transitions happen only on declared sequence points.
+		_nick->run_for(Cycles(1));
+		--next_sequence_point;
+		const bool interrupt_line = _nick->get_interrupt_line();
+
+		if(interrupt_line != last_interrupt_line) {
+			XCTAssertEqual(next_sequence_point, 0);
+		}
+		last_interrupt_line = interrupt_line;
+
+		if(!next_sequence_point) {
+			next_sequence_point = _nick->get_next_sequence_point().as<int>();
+		} else {
+			const int expected_next_sequence_point = _nick->get_next_sequence_point().as<int>();
+			XCTAssertEqual(next_sequence_point, expected_next_sequence_point);
+		}
+	}
+}
+
+@end

From 266310d9c2a17822fd7462a19a39f4ded264fcaf Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 18 Jun 2021 18:43:08 -0400
Subject: [PATCH 033/117] Fixes automatic flushing for non-1/1-clocked actors.

---
 ClockReceiver/JustInTime.hpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/ClockReceiver/JustInTime.hpp b/ClockReceiver/JustInTime.hpp
index 8d709559c..4f7c02018 100644
--- a/ClockReceiver/JustInTime.hpp
+++ b/ClockReceiver/JustInTime.hpp
@@ -103,9 +103,9 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
 			}
 
 			if constexpr (has_sequence_points<T>::value) {
-				time_until_event_ -= rhs;
+				time_until_event_ -= rhs * multiplier;
 				if(time_until_event_ <= LocalTimeScale(0)) {
-					time_overrun_ = time_until_event_;
+					time_overrun_ = time_until_event_ / divider;
 					flush();
 					update_sequence_point();
 					return true;
@@ -185,7 +185,7 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
 		/// @returns the number of cycles until the next sequence-point-based flush, if the embedded object
 		/// supports sequence points; @c LocalTimeScale() otherwise.
 		[[nodiscard]] LocalTimeScale cycles_until_implicit_flush() const {
-			return time_until_event_;
+			return time_until_event_ / divider;
 		}
 
 		/// Indicates whether a sequence-point-caused flush will occur if the specified period is added.
@@ -199,7 +199,7 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
 		/// Updates this template's record of the next sequence point.
 		void update_sequence_point() {
 			if constexpr (has_sequence_points<T>::value) {
-				time_until_event_ = object_.get_next_sequence_point();
+				time_until_event_ = object_.get_next_sequence_point() * divider;
 				assert(time_until_event_ > LocalTimeScale(0));
 			}
 		}

From 9a0022cfcba66f10b4a9a442409c2ca42c407f5f Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 18 Jun 2021 18:44:07 -0400
Subject: [PATCH 034/117] Removes temporary work.

---
 Machines/Enterprise/Enterprise.cpp | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 5b29c0979..b18fa0bed 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -94,8 +94,6 @@ class ConcreteMachine:
 			page<3>(0x00);
 		}
 
-		int halves = 0;
-
 		// MARK: - Z80::BusHandler.
 		forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
 			using PartialMachineCycle = CPU::Z80::PartialMachineCycle;
@@ -104,14 +102,11 @@ class ConcreteMachine:
 			// TODO: possibly apply an access penalty.
 
 
-			halves += cycle.length.as<int>();
 			if(nick_ += cycle.length) {
 				const auto nick = nick_.last_valid();
 				const bool nick_interrupt_line = nick->get_interrupt_line();
-				// TEMPORARY. The below should print a bunch of numbers like 15988 on the Enterprise splash screen.
 				if(nick_interrupt_line && !previous_nick_interrupt_line_) {
-					printf("Interrupt after %d\n", halves + nick_.last_sequence_point_overrun().as<int>());
-					halves = - nick_.last_sequence_point_overrun().as<int>();
+					// TODO: apply interrupt.
 				}
 				previous_nick_interrupt_line_ = nick_interrupt_line;
 			}

From 6af6f21868c481ea078f41a0483c4e01d348e54c Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 18 Jun 2021 22:59:41 -0400
Subject: [PATCH 035/117] Attempts to implement interrupt latches and clears.

---
 Machines/Enterprise/Enterprise.cpp | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index b18fa0bed..7a7ef88a6 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -106,7 +106,7 @@ class ConcreteMachine:
 				const auto nick = nick_.last_valid();
 				const bool nick_interrupt_line = nick->get_interrupt_line();
 				if(nick_interrupt_line && !previous_nick_interrupt_line_) {
-					// TODO: apply interrupt.
+					set_interrupt(Interrupt::Nick, nick_.last_sequence_point_overrun());
 				}
 				previous_nick_interrupt_line_ = nick_interrupt_line;
 			}
@@ -127,8 +127,7 @@ class ConcreteMachine:
 						case 0xb3:	*cycle.value = pages_[3];	break;
 
 						case 0xb4:
-							printf("TODO: interrupt enable/reset read\n");
-							*cycle.value = 0xff;
+							*cycle.value = interrupt_mask_ | interrupt_state_;
 						break;
 						case 0xb5:
 							if(active_key_line_ < key_lines_.size()) {
@@ -167,7 +166,9 @@ class ConcreteMachine:
 						break;
 
 						case 0xb4:
-							printf("TODO: interrupt enable/reset write %02x\n", *cycle.value);
+							interrupt_mask_ = *cycle.value & 0x55;
+							interrupt_state_ &= ~*cycle.value;
+							update_interrupts();
 						break;
 						case 0xb5:
 							active_key_line_ = *cycle.value & 0xf;
@@ -276,6 +277,23 @@ class ConcreteMachine:
 			key_lines_.fill(0xff);
 		}
 
+		// MARK: - Interrupts
+
+		// TODO: include an error.
+
+		enum class Interrupt: uint8_t {
+			Nick = 0x20
+		};
+
+		uint8_t interrupt_mask_ = 0x00, interrupt_state_ = 0x00;
+		void set_interrupt(Interrupt mask, HalfCycles offset = HalfCycles(0)) {
+			interrupt_state_ |= uint8_t(mask);
+			update_interrupts(offset);
+		}
+		void update_interrupts(HalfCycles offset = HalfCycles(0)) {
+			z80_.set_interrupt_line((interrupt_state_ >> 1) & interrupt_mask_, offset);
+		}
+
 		// MARK: - Chips.
 		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
 		JustInTimeActor<Nick, HalfCycles, 444923, 125000> nick_;

From 9411c37d233c4ff6ac129da5bc65457a18ff7350 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 18 Jun 2021 23:14:35 -0400
Subject: [PATCH 036/117] Fleshes out the keyboard map.

---
 Machines/Enterprise/Keyboard.cpp | 28 ++++++++++++++++++++++++++--
 Machines/Enterprise/Keyboard.hpp |  6 +++---
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/Machines/Enterprise/Keyboard.cpp b/Machines/Enterprise/Keyboard.cpp
index bf0d582e1..db3514a29 100644
--- a/Machines/Enterprise/Keyboard.cpp
+++ b/Machines/Enterprise/Keyboard.cpp
@@ -15,9 +15,29 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 	switch(key) {
 		default: break;
 
+		BIND(Backslash, Backslash);
+		BIND(CapsLock, Lock);
+		BIND(Tab, Tab);
+		BIND(Escape, Escape);
+		BIND(Hyphen, Hyphen);
+		BIND(Equals, Tilde);
+		BIND(Backspace, Erase);
+		BIND(Delete, Delete);
+		BIND(Semicolon, Semicolon);
+		BIND(Quote, Colon);
+		BIND(OpenSquareBracket, OpenSquareBracket);
+		BIND(CloseSquareBracket, CloseSquareBracket);
+
+		BIND(End, Stop);
+		BIND(Insert, Insert);
+		BIND(BackTick, At);
+
 		BIND(k1, k1);	BIND(k2, k2);	BIND(k3, k3);	BIND(k4, k4);	BIND(k5, k5);
 		BIND(k6, k6);	BIND(k7, k7);	BIND(k8, k8);	BIND(k9, k9);	BIND(k0, k0);
 
+		BIND(F1, F1);	BIND(F2, F2);	BIND(F3, F3);	BIND(F4, F4);
+		BIND(F5, F5);	BIND(F6, F6);	BIND(F7, F7);	BIND(F8, F8);
+
 		BIND(Q, Q);	BIND(W, W);	BIND(E, E);	BIND(R, R);	BIND(T, T);
 		BIND(Y, Y);	BIND(U, U);	BIND(I, I);	BIND(O, O);	BIND(P, P);
 
@@ -27,12 +47,16 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 		BIND(Z, Z);	BIND(X, X);	BIND(C, C);	BIND(V, V);
 		BIND(B, B);	BIND(N, N);	BIND(M, M);
 
+		BIND(FullStop, FullStop);
+		BIND(Comma, Comma);
+		BIND(ForwardSlash, ForwardSlash);
+
 		BIND(Space, Space);	BIND(Enter, Enter);
 
 		BIND(LeftShift, LeftShift);
 		BIND(RightShift, RightShift);
-		BIND(LeftOption, Option);
-		BIND(RightOption, Option);
+		BIND(LeftOption, Alt);
+		BIND(RightOption, Alt);
 		BIND(LeftControl, Control);
 		BIND(RightControl, Control);
 
diff --git a/Machines/Enterprise/Keyboard.hpp b/Machines/Enterprise/Keyboard.hpp
index 6ff2e83dc..0a13b7e1a 100644
--- a/Machines/Enterprise/Keyboard.hpp
+++ b/Machines/Enterprise/Keyboard.hpp
@@ -16,7 +16,7 @@ namespace Enterprise {
 #define KeyCode(line, mask)	(line << 8) | mask
 
 enum class Key: uint16_t {
-	N		= 0x0000 | 0x01,	BackSlash	= 0x0000 | 0x02,	B		= 0x0000 | 0x04,	C			= 0x0000 | 0x08,
+	N		= 0x0000 | 0x01,	Backslash	= 0x0000 | 0x02,	B		= 0x0000 | 0x04,	C			= 0x0000 | 0x08,
 	V		= 0x0000 | 0x10,	X 			= 0x0000 | 0x20,	Z		= 0x0000 | 0x40,	LeftShift	= 0x0000 | 0x80,
 
 	H		= 0x0100 | 0x01,	Lock		= 0x0100 | 0x02,	G		= 0x0100 | 0x04,	D			= 0x0100 | 0x08,
@@ -34,11 +34,11 @@ enum class Key: uint16_t {
 	k8		= 0x0500 | 0x01,									k9		= 0x0500 | 0x04,	Hyphen		= 0x0500 | 0x08,
 	k0		= 0x0500 | 0x10,	Tilde		= 0x0500 | 0x20,	Erase	= 0x0500 | 0x40,
 
-	J		= 0x0600 | 0x01,									K		= 0x0600 | 0x04,	SemiColon	= 0x0600 | 0x08,
+	J		= 0x0600 | 0x01,									K		= 0x0600 | 0x04,	Semicolon	= 0x0600 | 0x08,
 	L		= 0x0600 | 0x10,	Colon		= 0x0600 | 0x20,	CloseSquareBracket		= 0x0600 | 0x40,
 
 	Stop	= 0x0700 | 0x01,	Down		= 0x0700 | 0x02,	Right	= 0x0700 | 0x04,	Up			= 0x0700 | 0x08,
-	Hold	= 0x0700 | 0x10,	Left		= 0x0700 | 0x20,	Enter	= 0x0700 | 0x40,	Option		= 0x0700 | 0x80,
+	Hold	= 0x0700 | 0x10,	Left		= 0x0700 | 0x20,	Enter	= 0x0700 | 0x40,	Alt			= 0x0700 | 0x80,
 
 	M		= 0x0800 | 0x01,	Delete		= 0x0800 | 0x02,	Comma	= 0x0800 | 0x04,
 	ForwardSlash	= 0x0800 | 0x08,

From a381374e317ab738bf745efb312adff161b0bbb8 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 18 Jun 2021 23:14:44 -0400
Subject: [PATCH 037/117] Drops back down to 64kb.

---
 Machines/Enterprise/Enterprise.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 7a7ef88a6..83e37e91d 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -208,9 +208,9 @@ class ConcreteMachine:
 
 	private:
 		// MARK: - Memory layout
-		std::array<uint8_t, 256 * 1024> ram_;
+		std::array<uint8_t, 64 * 1024> ram_;
 		std::array<uint8_t, 64 * 1024> exos_;
-		const uint8_t min_ram_slot_ = 0xff - 16 + 1;
+		const uint8_t min_ram_slot_ = uint8_t(0x100 - (ram_.size() / 0x4000));
 
 		const uint8_t *read_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
 		uint8_t *write_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};

From 8f24aed43e622accc7602362e6c321a193f548ea Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 18 Jun 2021 23:17:44 -0400
Subject: [PATCH 038/117] Slightly reduces logging.

---
 Machines/Enterprise/Nick.cpp | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index ddaae8324..91b0707fd 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -44,7 +44,6 @@ Nick::Nick(const uint8_t *ram) :
 }
 
 void Nick::write(uint16_t address, uint8_t value) {
-	printf("Nick write: %02x -> %d\n", value, address & 3);
 	switch(address & 3) {
 		case 0:
 			// Ignored: everything to do with external colour.
@@ -65,8 +64,6 @@ void Nick::write(uint16_t address, uint8_t value) {
 			// Still a mystery to me: the exact meaning of the top two bits here. For now
 			// just treat a 0 -> 1 transition of the MSB as a forced frame restart.
 			if((value^line_parameter_control_) & value & 0x80) {
-				printf("Should restart frame from %04x\n", line_parameter_base_);
-
 				// For now: just force this to be the final line of this mode block.
 				// I'm unclear whether I should also reset the horizontal counter
 				// (i.e. completely abandon current video phase).

From 1651efe4fc1775a49ed21c0dce6cbe362d68e3a2 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 19 Jun 2021 13:03:31 -0400
Subject: [PATCH 039/117] Ensures all keys are initially unpressed.

---
 Machines/Enterprise/Enterprise.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 83e37e91d..1f9c156aa 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -81,6 +81,8 @@ class ConcreteMachine:
 			exos_.fill(0xff);
 			memcpy(exos_.data(), exos.data(), std::min(exos_.size(), exos.size()));
 
+			clear_all_keys();
+
 			// Take a reasonable guess at the initial memory configuration:
 			// put EXOS into the first bank since this is a Z80 and therefore
 			// starts from address 0; the third instruction in EXOS is a jump

From 1dcac304d3ee6fbac4c8399bb1ce4cf036b2b0b1 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 19 Jun 2021 13:04:18 -0400
Subject: [PATCH 040/117] Implements the ALTIND bits and attempts ATTR mode.

---
 Machines/Enterprise/Nick.cpp | 70 ++++++++++++++++++++++++++++++------
 Machines/Enterprise/Nick.hpp |  2 ++
 2 files changed, 61 insertions(+), 11 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 91b0707fd..64fa2034f 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -133,7 +133,7 @@ void Nick::run_for(Cycles duration) {
 					case Mode::CH128:
 					case Mode::CH256:
 					case Mode::LPixel:	column_size_ = 8 / bpp_;	break;
-//					case Mode::Attr:	column_size_ = 8;			break;
+					case Mode::Attr:	column_size_ = 8;			break;
 				}
 
 				// Act as if proper state transitions had occurred while HSYNC is being output.
@@ -158,6 +158,16 @@ void Nick::run_for(Cycles duration) {
 				for(int c = 0; c < 8; c++) {
 					palette_[c] = mapped_colour(line_parameters_[8 + c]);
 				}
+
+				// Use ALTIND0 and ALTIND1 to pick the alt_ind_palettes.
+				//
+				// ALTIND1 = b6 of params[3], if set => character codes with bit 7 set should use palette indices 2 and 3.
+				// ALTIND0 = b7 of params[3], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
+				alt_ind_palettes[0] = palette_;
+				alt_ind_palettes[2] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x40) ? 2 : 0);
+
+				alt_ind_palettes[1] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x80) ? 4 : 0);
+				alt_ind_palettes[3] = alt_ind_palettes[2] + ((line_parameters_[3] & 0x80) ? 4 : 0);
 			}
 		}
 
@@ -219,6 +229,7 @@ void Nick::run_for(Cycles duration) {
 #define ch256(x) output_character<x, 8>
 #define ch128(x) output_character<x, 7>
 #define ch64(x) output_character<x, 6>
+#define attr(x) output_attributed<x>
 
 						int columns_remaining = next_event - window;
 						while(columns_remaining) {
@@ -237,6 +248,7 @@ void Nick::run_for(Cycles duration) {
 									case Mode::CH256:	DispatchBpp(ch256);		break;
 									case Mode::CH128:	DispatchBpp(ch128);		break;
 									case Mode::CH64:	DispatchBpp(ch64);		break;
+									case Mode::Attr:	DispatchBpp(attr);		break;
 								}
 
 								pixel_pointer_ += output_duration * column_size_;
@@ -255,6 +267,7 @@ void Nick::run_for(Cycles duration) {
 							}
 
 						}
+#undef attr
 #undef ch64
 #undef ch128
 #undef ch256
@@ -306,6 +319,13 @@ void Nick::run_for(Cycles duration) {
 					line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
 					++line_data_pointer_[1];
 				break;
+
+				case Mode::Attr:
+					// Reload the attribute address if VRES is set.
+					if(line_parameters_[1] & 0x10) {
+						line_data_pointer_[1] = uint16_t(line_parameters_[6] | (line_parameters_[7] << 8));
+					}
+				break;
 			}
 		}
 	}
@@ -459,17 +479,45 @@ template <int bpp, int index_bits> void Nick::output_character(uint16_t *target,
 				assert(false);
 			break;
 
-			case 1:
-				target[0] = palette_[(pixels & 0x80) >> 7];
-				target[1] = palette_[(pixels & 0x40) >> 6];
-				target[2] = palette_[(pixels & 0x20) >> 5];
-				target[3] = palette_[(pixels & 0x10) >> 4];
-				target[4] = palette_[(pixels & 0x08) >> 3];
-				target[5] = palette_[(pixels & 0x04) >> 2];
-				target[6] = palette_[(pixels & 0x02) >> 1];
-				target[7] = palette_[(pixels & 0x01) >> 0];
+			case 1: {
+				// This applies ALTIND0 and ALTIND1.
+				const uint16_t *palette = alt_ind_palettes[character >> 6];
+				target[0] = palette[(pixels & 0x80) >> 7];
+				target[1] = palette[(pixels & 0x40) >> 6];
+				target[2] = palette[(pixels & 0x20) >> 5];
+				target[3] = palette[(pixels & 0x10) >> 4];
+				target[4] = palette[(pixels & 0x08) >> 3];
+				target[5] = palette[(pixels & 0x04) >> 2];
+				target[6] = palette[(pixels & 0x02) >> 1];
+				target[7] = palette[(pixels & 0x01) >> 0];
 				target += 8;
-			break;
+			} break;
 		}
 	}
 }
+
+template <int bpp> void Nick::output_attributed(uint16_t *target, int columns) {
+	static_assert(bpp == 1 || bpp == 2 || bpp == 4 || bpp == 8);
+
+	for(int c = 0; c < columns; c++) {
+		const uint8_t pixels = ram_[line_data_pointer_[0]];
+		const uint8_t attributes = ram_[line_data_pointer_[1]];
+
+		++line_data_pointer_[0];
+		++line_data_pointer_[1];
+
+		const uint16_t palette[2] = {
+			palette_[attributes >> 4], palette_[attributes & 0x0f]
+		};
+
+		target[0] = palette[(pixels & 0x80) >> 7];
+		target[1] = palette[(pixels & 0x40) >> 6];
+		target[2] = palette[(pixels & 0x20) >> 5];
+		target[3] = palette[(pixels & 0x10) >> 4];
+		target[4] = palette[(pixels & 0x08) >> 3];
+		target[5] = palette[(pixels & 0x04) >> 2];
+		target[6] = palette[(pixels & 0x02) >> 1];
+		target[7] = palette[(pixels & 0x01) >> 0];
+		target += 8;
+	}
+}
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 2e4dcf1cb..d958d38d5 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -56,6 +56,7 @@ class Nick {
 		// Current mode line parameters.
 		uint8_t lines_remaining_ = 0x00;
 		int left_margin_ = 0, right_margin_ = 0;
+		const uint16_t *alt_ind_palettes[4];
 		enum class Mode {
 			Vsync,
 			Pixel,
@@ -93,6 +94,7 @@ class Nick {
 		// Specific outputters.
 		template <int bpp, bool is_lpixel> void output_pixel(uint16_t *target, int columns);
 		template <int bpp, int index_bits> void output_character(uint16_t *target, int columns);
+		template <int bpp> void output_attributed(uint16_t *target, int columns);
 };
 
 

From 4968ccf46d75237d32ea5b60da93cfe376b3ea07 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 19 Jun 2021 13:08:14 -0400
Subject: [PATCH 041/117] Corrects attributed mode.

---
 Machines/Enterprise/Nick.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 64fa2034f..82e979845 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -323,7 +323,7 @@ void Nick::run_for(Cycles duration) {
 				case Mode::Attr:
 					// Reload the attribute address if VRES is set.
 					if(line_parameters_[1] & 0x10) {
-						line_data_pointer_[1] = uint16_t(line_parameters_[6] | (line_parameters_[7] << 8));
+						line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
 					}
 				break;
 			}
@@ -500,8 +500,8 @@ template <int bpp> void Nick::output_attributed(uint16_t *target, int columns) {
 	static_assert(bpp == 1 || bpp == 2 || bpp == 4 || bpp == 8);
 
 	for(int c = 0; c < columns; c++) {
-		const uint8_t pixels = ram_[line_data_pointer_[0]];
-		const uint8_t attributes = ram_[line_data_pointer_[1]];
+		const uint8_t pixels = ram_[line_data_pointer_[1]];
+		const uint8_t attributes = ram_[line_data_pointer_[0]];
 
 		++line_data_pointer_[0];
 		++line_data_pointer_[1];

From fadb04f3f3bc1df310d2d43a023db1d0d9158eed Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 19 Jun 2021 21:57:26 -0400
Subject: [PATCH 042/117] Attempts to implement LSBALT and MSBALT.

---
 Machines/Enterprise/Nick.cpp | 86 +++++++++++++++++++++++++-----------
 Machines/Enterprise/Nick.hpp |  1 +
 2 files changed, 60 insertions(+), 27 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 82e979845..2bcf726ab 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -159,15 +159,41 @@ void Nick::run_for(Cycles duration) {
 					palette_[c] = mapped_colour(line_parameters_[8 + c]);
 				}
 
-				// Use ALTIND0 and ALTIND1 to pick the alt_ind_palettes.
-				//
-				// ALTIND1 = b6 of params[3], if set => character codes with bit 7 set should use palette indices 2 and 3.
-				// ALTIND0 = b7 of params[3], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
-				alt_ind_palettes[0] = palette_;
-				alt_ind_palettes[2] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x40) ? 2 : 0);
+				switch(mode_) {
+					default:
+					break;
 
-				alt_ind_palettes[1] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x80) ? 4 : 0);
-				alt_ind_palettes[3] = alt_ind_palettes[2] + ((line_parameters_[3] & 0x80) ? 4 : 0);
+					// NB: LSBALT/MSBALT and ALTIND0/ALTIND1 appear to have opposite effects on palette selection.
+
+					case Mode::Pixel:
+					case Mode::LPixel:
+						// Use MSBALT and LSBALT to pick the alt_ind_palettes.
+						//
+						// LSBALT = b6 of params[2], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
+						// MSBALT = b7 of params[2], if set => character codes with bit 7 set should use palette indices 2 and 3.
+						two_colour_mask_ = 0xff &~ (((line_parameters_[2]&0x80) >> 7) | ((line_parameters_[2]&0x40) << 1));
+
+						alt_ind_palettes[0] = palette_;
+						alt_ind_palettes[2] = alt_ind_palettes[0] + ((line_parameters_[2] & 0x80) ? 2 : 0);
+
+						alt_ind_palettes[1] = alt_ind_palettes[0] + ((line_parameters_[2] & 0x40) ? 4 : 0);
+						alt_ind_palettes[3] = alt_ind_palettes[2] + ((line_parameters_[2] & 0x40) ? 4 : 0);
+					break;
+
+					case Mode::CH64:
+					case Mode::CH128:
+					case Mode::CH256:
+						// Use ALTIND0 and ALTIND1 to pick the alt_ind_palettes.
+						//
+						// ALTIND1 = b6 of params[3], if set => character codes with bit 7 set should use palette indices 2 and 3.
+						// ALTIND0 = b7 of params[3], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
+						alt_ind_palettes[0] = palette_;
+						alt_ind_palettes[2] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x40) ? 2 : 0);
+
+						alt_ind_palettes[1] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x80) ? 4 : 0);
+						alt_ind_palettes[3] = alt_ind_palettes[2] + ((line_parameters_[3] & 0x80) ? 4 : 0);
+					break;
+				}
 			}
 		}
 
@@ -382,36 +408,42 @@ template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int
 	static_assert(bpp == 1 || bpp == 2 || bpp == 4 || bpp == 8);
 
 	for(int c = 0; c < columns; c++) {
-		const uint8_t pixels[2] = { ram_[line_data_pointer_[0]], ram_[(line_data_pointer_[0]+1) & 0xffff] };
+		uint8_t pixels[2] = { ram_[line_data_pointer_[0]], ram_[(line_data_pointer_[0]+1) & 0xffff] };
 		line_data_pointer_[0] += is_lpixel ? 1 : 2;
 
 		switch(bpp) {
 			default:
-			case 1:
-				target[0] = palette_[(pixels[0] & 0x80) >> 7];
-				target[1] = palette_[(pixels[0] & 0x40) >> 6];
-				target[2] = palette_[(pixels[0] & 0x20) >> 5];
-				target[3] = palette_[(pixels[0] & 0x10) >> 4];
-				target[4] = palette_[(pixels[0] & 0x08) >> 3];
-				target[5] = palette_[(pixels[0] & 0x04) >> 2];
-				target[6] = palette_[(pixels[0] & 0x02) >> 1];
-				target[7] = palette_[(pixels[0] & 0x01) >> 0];
+			case 1: {
+				const uint16_t *palette = alt_ind_palettes[((pixels[0] >> 6) & 0x02) | (pixels[0]&1)];
+				pixels[0] &= two_colour_mask_;
+
+				target[0] = palette[(pixels[0] & 0x80) >> 7];
+				target[1] = palette[(pixels[0] & 0x40) >> 6];
+				target[2] = palette[(pixels[0] & 0x20) >> 5];
+				target[3] = palette[(pixels[0] & 0x10) >> 4];
+				target[4] = palette[(pixels[0] & 0x08) >> 3];
+				target[5] = palette[(pixels[0] & 0x04) >> 2];
+				target[6] = palette[(pixels[0] & 0x02) >> 1];
+				target[7] = palette[(pixels[0] & 0x01) >> 0];
 
 				if constexpr (!is_lpixel) {
-					target[8] = palette_[(pixels[1] & 0x80) >> 7];
-					target[9] = palette_[(pixels[1] & 0x40) >> 6];
-					target[10] = palette_[(pixels[1] & 0x20) >> 5];
-					target[11] = palette_[(pixels[1] & 0x10) >> 4];
-					target[12] = palette_[(pixels[1] & 0x08) >> 3];
-					target[13] = palette_[(pixels[1] & 0x04) >> 2];
-					target[14] = palette_[(pixels[1] & 0x02) >> 1];
-					target[15] = palette_[(pixels[1] & 0x01) >> 0];
+					palette = alt_ind_palettes[((pixels[1] >> 6) & 0x02) | (pixels[1]&1)];
+					pixels[1] &= two_colour_mask_;
+
+					target[8] = palette[(pixels[1] & 0x80) >> 7];
+					target[9] = palette[(pixels[1] & 0x40) >> 6];
+					target[10] = palette[(pixels[1] & 0x20) >> 5];
+					target[11] = palette[(pixels[1] & 0x10) >> 4];
+					target[12] = palette[(pixels[1] & 0x08) >> 3];
+					target[13] = palette[(pixels[1] & 0x04) >> 2];
+					target[14] = palette[(pixels[1] & 0x02) >> 1];
+					target[15] = palette[(pixels[1] & 0x01) >> 0];
 
 					target += 8;
 				}
 
 				target += 8;
-			break;
+			} break;
 
 			case 2:
 				target[0] = palette_[((pixels[0] & 0x80) >> 6) | ((pixels[0] & 0x08) >> 3)];
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index d958d38d5..31cf03be9 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -55,6 +55,7 @@ class Nick {
 
 		// Current mode line parameters.
 		uint8_t lines_remaining_ = 0x00;
+		uint8_t two_colour_mask_ = 0xff;
 		int left_margin_ = 0, right_margin_ = 0;
 		const uint16_t *alt_ind_palettes[4];
 		enum class Mode {

From 23e26e0333c2cf9fd9463fc0129e12d961c0393b Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 19 Jun 2021 22:00:19 -0400
Subject: [PATCH 043/117] Attempts to complete handling of VRES.

---
 Machines/Enterprise/Nick.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 2bcf726ab..0daf02717 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -336,7 +336,7 @@ void Nick::run_for(Cycles duration) {
 				}
 			}
 
-			// TODO: logic below is very incomplete.
+			// Deal with VRES and other address reloading, dependant upon mode.
 			switch(mode_) {
 				default: break;
 				case Mode::CH64:
@@ -352,6 +352,14 @@ void Nick::run_for(Cycles duration) {
 						line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
 					}
 				break;
+
+				case Mode::Pixel:
+				case Mode::LPixel:
+					// If VRES is clear, reload the pixel address.
+					if(!(line_parameters_[1] & 0x10)) {
+						line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
+					}
+				break;
 			}
 		}
 	}

From 42a98e1676d10e57ae28d1ce715ef64643b3589c Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 19 Jun 2021 22:13:17 -0400
Subject: [PATCH 044/117] Fix composition with empty nodes.

---
 Machines/Utility/ROMCatalogue.cpp | 11 +++++++++--
 Machines/Utility/ROMCatalogue.hpp |  4 ++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/Machines/Utility/ROMCatalogue.cpp b/Machines/Utility/ROMCatalogue.cpp
index 643b72a9e..23bf6f1a8 100644
--- a/Machines/Utility/ROMCatalogue.cpp
+++ b/Machines/Utility/ROMCatalogue.cpp
@@ -27,8 +27,15 @@ Request::Request(Name name, bool optional) {
 }
 
 Request Request::append(Node::Type type, const Request &rhs) {
-	// Start with the easiest case: this is already an appropriate
-	// request, and so is the new thing.
+	// If either side is empty, act appropriately.
+	if(node.empty() && !rhs.node.empty()) {
+		return rhs;
+	}
+	if(rhs.node.empty()) {
+		return *this;
+	}
+
+	// Just copy in the RHS child nodes if types match.
 	if(node.type == type && rhs.node.type == type) {
 		Request new_request = *this;
 		new_request.node.children.insert(new_request.node.children.end(), rhs.node.children.begin(), rhs.node.children.end());
diff --git a/Machines/Utility/ROMCatalogue.hpp b/Machines/Utility/ROMCatalogue.hpp
index a9f457b95..5fabd093a 100644
--- a/Machines/Utility/ROMCatalogue.hpp
+++ b/Machines/Utility/ROMCatalogue.hpp
@@ -240,6 +240,10 @@ struct Request {
 			bool is_optional = false;
 			std::vector<Node> children;
 
+			bool empty() const {
+				return type == Type::One && name == Name::None;
+			}
+
 			void add_descriptions(std::vector<Description> &) const;
 			bool validate(Map &) const;
 			void visit(

From 0e1e8c7faafcf58dc1a9284bb4e793c2887329c6 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 19 Jun 2021 22:59:09 -0400
Subject: [PATCH 045/117] Attempts to support the panoply of EXOS and BASIC
 versions.

---
 Analyser/Static/Enterprise/Target.hpp | 16 ++++-
 Machines/Enterprise/Enterprise.cpp    | 92 +++++++++++++++++++++++++--
 Machines/Utility/ROMCatalogue.cpp     | 48 +++++++++++++-
 Machines/Utility/ROMCatalogue.hpp     | 12 +++-
 4 files changed, 155 insertions(+), 13 deletions(-)

diff --git a/Analyser/Static/Enterprise/Target.hpp b/Analyser/Static/Enterprise/Target.hpp
index f77f01f50..d758e4d6d 100644
--- a/Analyser/Static/Enterprise/Target.hpp
+++ b/Analyser/Static/Enterprise/Target.hpp
@@ -18,9 +18,21 @@ namespace Static {
 namespace Enterprise {
 
 struct Target: public Analyser::Static::Target, public Reflection::StructImpl<Target> {
-	Target() : Analyser::Static::Target(Machine::Enterprise) {}
+	ReflectableEnum(EXOSVersion, v10, v20, v21, v23, Any);
+	ReflectableEnum(BASICVersion, v10, v11, v21, Any, None);
 
-	// TODO: I assume there'll be relevant fields to add here.
+	EXOSVersion exos_version = EXOSVersion::Any;
+	BASICVersion basic_version = BASICVersion::None;
+
+	Target() : Analyser::Static::Target(Machine::Enterprise) {
+		if(needs_declare()) {
+			AnnounceEnum(EXOSVersion);
+			AnnounceEnum(BASICVersion);
+
+			DeclareField(exos_version);
+			DeclareField(basic_version);
+		}
+	}
 };
 
 }
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 1f9c156aa..269a08412 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -70,17 +70,92 @@ class ConcreteMachine:
 			// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
 			set_clock_rate(4'000'000);
 
-			constexpr ROM::Name exos_name = ROM::Name::EnterpriseEXOS;
-			const auto request = ROM::Request(exos_name);
+			ROM::Request request;
+			using Target = Analyser::Static::Enterprise::Target;
+
+			// Pick one or more EXOS ROMs.
+			switch(target.exos_version) {
+				case Target::EXOSVersion::v10:	request = request && ROM::Request(ROM::Name::EnterpriseEXOS10);	break;
+				case Target::EXOSVersion::v20:	request = request && ROM::Request(ROM::Name::EnterpriseEXOS20);	break;
+				case Target::EXOSVersion::v21:	request = request && ROM::Request(ROM::Name::EnterpriseEXOS21);	break;
+				case Target::EXOSVersion::v23:	request = request && ROM::Request(ROM::Name::EnterpriseEXOS23);	break;
+				case Target::EXOSVersion::Any:
+					request =
+						request && (
+							ROM::Request(ROM::Name::EnterpriseEXOS10) || ROM::Request(ROM::Name::EnterpriseEXOS20) ||
+							ROM::Request(ROM::Name::EnterpriseEXOS21) || ROM::Request(ROM::Name::EnterpriseEXOS23)
+						);
+				break;
+
+				default: break;
+			}
+
+			// Similarly pick one or more BASIC ROMs.
+			switch(target.basic_version) {
+				case Target::BASICVersion::v10:
+					request = request && (
+						ROM::Request(ROM::Name::EnterpriseBASIC10) ||
+						(ROM::Request(ROM::Name::EnterpriseBASIC10Part1) && ROM::Request(ROM::Name::EnterpriseBASIC10Part2))
+					);
+				break;
+				case Target::BASICVersion::v11:
+					request = request && (
+						ROM::Request(ROM::Name::EnterpriseBASIC11) ||
+						ROM::Request(ROM::Name::EnterpriseBASIC11Suffixed)
+					);
+				case Target::BASICVersion::v21:
+					request = request && ROM::Request(ROM::Name::EnterpriseBASIC21);
+				break;
+				case Target::BASICVersion::Any:
+					request =
+						request && (
+							ROM::Request(ROM::Name::EnterpriseBASIC10) ||
+							(ROM::Request(ROM::Name::EnterpriseBASIC10Part1) && ROM::Request(ROM::Name::EnterpriseBASIC10Part2)) ||
+							ROM::Request(ROM::Name::EnterpriseBASIC11) ||
+							ROM::Request(ROM::Name::EnterpriseBASIC21)
+						);
+				break;
+
+				default: break;
+			}
+
+			// Get and validate ROMs.
 			auto roms = rom_fetcher(request);
 			if(!request.validate(roms)) {
 				throw ROMMachine::Error::MissingROMs;
 			}
 
-			const auto &exos = roms.find(exos_name)->second;
+			// Extract the appropriate EXOS ROM.
 			exos_.fill(0xff);
-			memcpy(exos_.data(), exos.data(), std::min(exos_.size(), exos.size()));
+			for(const auto rom_name: { ROM::Name::EnterpriseEXOS10, ROM::Name::EnterpriseEXOS20, ROM::Name::EnterpriseEXOS21, ROM::Name::EnterpriseEXOS23 }) {
+				const auto exos = roms.find(rom_name);
+				if(exos != roms.end()) {
+					memcpy(exos_.data(), exos->second.data(), std::min(exos_.size(), exos->second.size()));
+					break;
+				}
+			}
 
+			// Extract the appropriate BASIC ROM[s] (if any).
+			basic_.fill(0xff);
+			bool has_basic = false;
+			for(const auto rom_name: { ROM::Name::EnterpriseBASIC10, ROM::Name::EnterpriseBASIC11, ROM::Name::EnterpriseBASIC11Suffixed, ROM::Name::EnterpriseBASIC21 }) {
+				const auto basic = roms.find(rom_name);
+				if(basic != roms.end()) {
+					memcpy(basic_.data(), basic->second.data(), std::min(basic_.size(), basic->second.size()));
+					has_basic = true;
+					break;
+				}
+			}
+			if(!has_basic) {
+				const auto basic1 = roms.find(ROM::Name::EnterpriseBASIC10Part1);
+				const auto basic2 = roms.find(ROM::Name::EnterpriseBASIC10Part2);
+				if(basic1 != roms.end() && basic2 != roms.end()) {
+					memcpy(&basic_[0x0000], basic1->second.data(), std::min(size_t(8192), basic1->second.size()));
+					memcpy(&basic_[0x2000], basic2->second.data(), std::min(size_t(8192), basic2->second.size()));
+				}
+			}
+
+			// Seed key state.
 			clear_all_keys();
 
 			// Take a reasonable guess at the initial memory configuration:
@@ -212,6 +287,7 @@ class ConcreteMachine:
 		// MARK: - Memory layout
 		std::array<uint8_t, 64 * 1024> ram_;
 		std::array<uint8_t, 64 * 1024> exos_;
+		std::array<uint8_t, 16 * 1024> basic_;
 		const uint8_t min_ram_slot_ = uint8_t(0x100 - (ram_.size() / 0x4000));
 
 		const uint8_t *read_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
@@ -226,6 +302,11 @@ class ConcreteMachine:
 				return;
 			}
 
+			if(offset >= 16 && offset < 16 + basic_.size() / 0x4000) {
+				page<slot>(&basic_[(offset - 16) * 0x4000], nullptr);
+				return;
+			}
+
 			// Of whatever size of RAM I've declared above, use only the final portion.
 			// This correlated with Nick always having been handed the final 64kb and,
 			// at least while the RAM is the first thing declared above, does a little
@@ -280,9 +361,6 @@ class ConcreteMachine:
 		}
 
 		// MARK: - Interrupts
-
-		// TODO: include an error.
-
 		enum class Interrupt: uint8_t {
 			Nick = 0x20
 		};
diff --git a/Machines/Utility/ROMCatalogue.cpp b/Machines/Utility/ROMCatalogue.cpp
index 23bf6f1a8..d245e98bb 100644
--- a/Machines/Utility/ROMCatalogue.cpp
+++ b/Machines/Utility/ROMCatalogue.cpp
@@ -411,9 +411,51 @@ Description::Description(Name name) {
 			*this = Description(name, "DiskII", "the Disk II 13-sector state machine ROM", "state-machine-13.rom", 256, 0x62e22620u);
 		break;
 
-		case Name::EnterpriseEXOS: {
-			const std::initializer_list<std::string> filenames = {"exos.bin", "Exos (198x)(Enterprise).bin"};
-			*this = Description(name, "Enterprise", "the Enterprise EXOS ROM", filenames, 32 * 1024, 0x30b26387u);
+		case Name::EnterpriseEXOS10: {
+			const std::initializer_list<std::string> filenames = {"exos10.bin", "Exos (198x)(Enterprise).bin"};
+			*this = Description(name, "Enterprise", "the Enterprise EXOS ROM v1.0", filenames, 32 * 1024, 0x30b26387u);
+		} break;
+		case Name::EnterpriseEXOS20: {
+			const std::initializer_list<std::string> filenames = {"exos20.bin", "Expandible OS v2.0 (1984)(Intelligent Software).bin"};
+			*this = Description(name, "Enterprise", "the Enterprise EXOS ROM v2.0", filenames, 32 * 1024, 0xd421795fu);
+		} break;
+		case Name::EnterpriseEXOS21: {
+			const std::initializer_list<std::string> filenames = {"exos21.bin", "Expandible OS v2.1 (1985)(Intelligent Software).bin"};
+			*this = Description(name, "Enterprise", "the Enterprise EXOS ROM v2.1", filenames, 32 * 1024, 0x982a3b44u);
+		} break;
+		case Name::EnterpriseEXOS23: {
+			const std::initializer_list<std::string> filenames = {"exos23.bin", "Expandible OS v2.3 (1987)(Intelligent Software).bin"};
+			*this = Description(name, "Enterprise", "the Enterprise EXOS ROM v2.1", filenames, 64 * 1024, 0x24838410u);
+		} break;
+
+		case Name::EnterpriseBASIC10: {
+			const std::initializer_list<std::string> filenames = {"basic10.bin"};
+			*this = Description(name, "Enterprise", "the Enterprise BASIC ROM v1.0", filenames, 16 * 1024, 0xd62e4fb7u);
+		} break;
+		case Name::EnterpriseBASIC10Part1: {
+			const std::initializer_list<std::string> filenames = {"BASIC 1.0 - EPROM 1-2 (198x)(Enterprise).bin"};
+			*this = Description(name, "Enterprise", "the Enterprise BASIC ROM v1.0, Part 1", filenames, 8193, 0x37bf48e1u);
+		} break;
+		case Name::EnterpriseBASIC10Part2: {
+			const std::initializer_list<std::string> filenames = {"BASIC 1.0 - EPROM 2-2 (198x)(Enterprise).bin"};
+			*this = Description(name, "Enterprise", "the Enterprise BASIC ROM v1.0, Part 2", filenames, 8193, 0xc5298c79u);
+		} break;
+		case Name::EnterpriseBASIC11: {
+			const std::initializer_list<std::string> filenames = {"basic11.bin"};
+			*this = Description(name, "Enterprise", "the Enterprise BASIC ROM v1.1", filenames, 16 * 1024, 0x683cf455u);
+		} break;
+		case Name::EnterpriseBASIC11Suffixed: {
+			const std::initializer_list<std::string> filenames = {"BASIC 1.1 - EPROM 1.1 (198x)(Enterprise).bin"};
+			*this = Description(name, "Enterprise", "the Enterprise BASIC ROM v1.1, with trailing byte", filenames, 16385, 0xc96b7602u);
+		} break;
+		case Name::EnterpriseBASIC21: {
+			const std::initializer_list<std::string> filenames = {
+				"basic21.bin",
+				"BASIC Interpreter v2.1 (1985)(Intelligent Software).bin",
+				"BASIC Interpreter v2.1 (1985)(Intelligent Software)[a].bin"
+			};
+			const std::initializer_list<uint32_t> crcs = { 0x55f96251, 0x683cf455 };
+			*this = Description(name, "Enterprise", "the Enterprise BASIC ROM v2.1", filenames, 16 * 1024, crcs);
 		} break;
 
 		case Name::Macintosh128k:	*this = Description(name, "Macintosh", "the Macintosh 128k ROM", "mac128k.rom", 64*1024, 0x6d0c8a28u);	break;
diff --git a/Machines/Utility/ROMCatalogue.hpp b/Machines/Utility/ROMCatalogue.hpp
index 5fabd093a..56b4e2c07 100644
--- a/Machines/Utility/ROMCatalogue.hpp
+++ b/Machines/Utility/ROMCatalogue.hpp
@@ -72,7 +72,17 @@ enum Name {
 	DiskIIBoot13Sector,
 
 	// Enterprise.
-	EnterpriseEXOS,
+	EnterpriseEXOS10,
+	EnterpriseEXOS20,
+	EnterpriseEXOS21,
+	EnterpriseEXOS23,
+
+	EnterpriseBASIC10,
+	EnterpriseBASIC10Part1,
+	EnterpriseBASIC10Part2,
+	EnterpriseBASIC11,
+	EnterpriseBASIC11Suffixed,
+	EnterpriseBASIC21,
 
 	// Macintosh.
 	Macintosh128k,

From 199621db0873af904cb47be73f2374a8dffecf90 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 19 Jun 2021 23:11:51 -0400
Subject: [PATCH 046/117] Observes that the actual guess here is MS-DOS-style.

---
 Storage/Disk/DiskImage/Formats/MSXDSK.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Storage/Disk/DiskImage/Formats/MSXDSK.hpp b/Storage/Disk/DiskImage/Formats/MSXDSK.hpp
index 23975a11e..f88c46754 100644
--- a/Storage/Disk/DiskImage/Formats/MSXDSK.hpp
+++ b/Storage/Disk/DiskImage/Formats/MSXDSK.hpp
@@ -17,7 +17,7 @@ namespace Storage {
 namespace Disk {
 
 /*!
-	Provides a @c DiskImage descriging an MSX-style disk image:
+	Provides a @c DiskImage describing an MSDOS-style disk image:
 	a sector dump of appropriate proportions.
 */
 class MSXDSK: public MFMSectorDump {

From a08d65b1ffb7b45c431816c146ead42f116cfed9 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 19 Jun 2021 23:16:33 -0400
Subject: [PATCH 047/117] Adds IMG -> Enterprise connection.

Albeit still without an Enterprise static analyser.
---
 Analyser/Static/StaticAnalyser.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Analyser/Static/StaticAnalyser.cpp b/Analyser/Static/StaticAnalyser.cpp
index 589f3f206..016869b1e 100644
--- a/Analyser/Static/StaticAnalyser.cpp
+++ b/Analyser/Static/StaticAnalyser.cpp
@@ -157,6 +157,7 @@ static Media GetMediaAndPlatforms(const std::string &file_name, TargetPlatform::
 			// HFE (TODO: switch to AllDisk once the MSX stops being so greedy)
 	Format("img", result.disks, Disk::DiskImageHolder<Storage::Disk::MacintoshIMG>, TargetPlatform::Macintosh)		// IMG (DiskCopy 4.2)
 	Format("image", result.disks, Disk::DiskImageHolder<Storage::Disk::MacintoshIMG>, TargetPlatform::Macintosh)	// IMG (DiskCopy 4.2)
+	Format("img", result.disks, Disk::DiskImageHolder<Storage::Disk::MSXDSK>, TargetPlatform::Enterprise)		// IMG (Enterprise/MS-DOS style)
 	Format("msa", result.disks, Disk::DiskImageHolder<Storage::Disk::MSA>, TargetPlatform::AtariST)				// MSA
 	Format("nib", result.disks, Disk::DiskImageHolder<Storage::Disk::NIB>, TargetPlatform::DiskII)				// NIB
 	Format("o", result.tapes, Tape::ZX80O81P, TargetPlatform::ZX8081)											// O

From 07dc26f8fa9f2be2fd6098ccdf2b0c2efee065ef Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 19 Jun 2021 23:41:29 -0400
Subject: [PATCH 048/117] Adds TODO to resolve screen jumping.

---
 Machines/Enterprise/Nick.cpp                                 | 5 +++--
 .../xcshareddata/xcschemes/Clock Signal Kiosk.xcscheme       | 4 ++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 0daf02717..17fc34805 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -284,14 +284,15 @@ void Nick::run_for(Cycles duration) {
 								}
 								columns_remaining -= output_duration;
 							} else {
-								// Advance pixel pointer upwards, so as to be able to supply something
+								// TODO: advance line pointers.
+
+								// Advance pixel pointer, so as to be able to supply something
 								// convincing to the CRT as to the number of samples that would have
 								// been provided, and skip asking for further allocations for now.
 								pixel_pointer_ += columns_remaining * column_size_;
 								pixel_duration_ += columns_remaining;
 								columns_remaining = 0;
 							}
-
 						}
 #undef attr
 #undef ch64
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal Kiosk.xcscheme b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal Kiosk.xcscheme
index d3942a20a..04eb4197f 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal Kiosk.xcscheme	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal Kiosk.xcscheme	
@@ -88,6 +88,10 @@
             argument = "--new=enterprise"
             isEnabled = "YES">
          </CommandLineArgument>
+         <CommandLineArgument
+            argument = "--basic-version=any"
+            isEnabled = "YES">
+         </CommandLineArgument>
          <CommandLineArgument
             argument = "&quot;/Users/thomasharte/Library/Mobile Documents/com~apple~CloudDocs/Desktop/Soft/ColecoVision/Galaxian (1983)(Atari).col&quot;"
             isEnabled = "NO">

From 2fe15a61688b7467336e0589d8ec1d2a7b098e54 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 20 Jun 2021 14:21:56 -0400
Subject: [PATCH 049/117] Switch to idealised Nick clock rate.

---
 Machines/Enterprise/Enterprise.cpp | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 269a08412..cf6674bdd 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -40,14 +40,11 @@ namespace Enterprise {
 	I shall _guess_ that the Enterprise stretches each line to 284 colour cycles rather than
 	reducing it to 283.
 
-	Therefore 912 cycles occurs in 284/283.7516 * 64 µs, which would appear to give an ideal
-	clock rate of around:
+	Therefore 912 cycles occurs in 284/283.7516 * 64 µs.
 
-		14,237,536.27 Hz.
-
-	Given that there's always some leeway in a receiver, I'm modelling that as 14,237,536 cycles,
-	which means that Nick runs 444923/125000 times as fast as the Z80. Which is around 3.56 times
-	as fast.
+	So one line = 181760000 / 2837516 µs = 45440000 / 709379 µs
+	=> one cycle = 45440000 / 709379*912 = 45440000 / 646953648 = 2840000 / 40434603 µs
+	=> clock rate of 40434603 / 2840000 Mhz
 
 	If that's true then the 6-cycle window is around 1.69 Z80 cycles long. Given that the Z80
 	clock in an Enterprise can be stopped in half-cycle increments only, the Z80 can only be
@@ -376,7 +373,7 @@ class ConcreteMachine:
 
 		// MARK: - Chips.
 		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
-		JustInTimeActor<Nick, HalfCycles, 444923, 125000> nick_;
+		JustInTimeActor<Nick, HalfCycles, 40434603, 2840000> nick_; 
 		bool previous_nick_interrupt_line_ = false;
 		// Cf. timing guesses above.
 };

From 09dbff39f239bad75d7406c16527b2ba909ecee0 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 20 Jun 2021 14:25:28 -0400
Subject: [PATCH 050/117] Also map keypad to F keys.

This is a pragmatic and arguably Apple-centric decision. But also it's fairly arbitrary, as the Enterprise doesn't have a number pad.
---
 Machines/Enterprise/Keyboard.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Machines/Enterprise/Keyboard.cpp b/Machines/Enterprise/Keyboard.cpp
index db3514a29..4c2444df3 100644
--- a/Machines/Enterprise/Keyboard.cpp
+++ b/Machines/Enterprise/Keyboard.cpp
@@ -38,6 +38,9 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 		BIND(F1, F1);	BIND(F2, F2);	BIND(F3, F3);	BIND(F4, F4);
 		BIND(F5, F5);	BIND(F6, F6);	BIND(F7, F7);	BIND(F8, F8);
 
+		BIND(Keypad1, F1);	BIND(Keypad2, F2);	BIND(Keypad3, F3);	BIND(Keypad4, F4);
+		BIND(Keypad5, F5);	BIND(Keypad6, F6);	BIND(Keypad7, F7);	BIND(Keypad8, F8);
+
 		BIND(Q, Q);	BIND(W, W);	BIND(E, E);	BIND(R, R);	BIND(T, T);
 		BIND(Y, Y);	BIND(U, U);	BIND(I, I);	BIND(O, O);	BIND(P, P);
 

From d8b9cdf7a218137ffd7c413b8daa00d28da108be Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 20 Jun 2021 14:25:37 -0400
Subject: [PATCH 051/117] Correct multiplier.

---
 Machines/Enterprise/Enterprise.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index cf6674bdd..cb62888fd 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -46,6 +46,12 @@ namespace Enterprise {
 	=> one cycle = 45440000 / 709379*912 = 45440000 / 646953648 = 2840000 / 40434603 µs
 	=> clock rate of 40434603 / 2840000 Mhz
 
+	And, therefore, the ratio to a 4Mhz Z80 clock is:
+
+		40434603 / (2840000 * 4)
+		= 40434603 / 11360000
+		i.e. roughly 3.55 Nick cycles per Z80 cycle.
+
 	If that's true then the 6-cycle window is around 1.69 Z80 cycles long. Given that the Z80
 	clock in an Enterprise can be stopped in half-cycle increments only, the Z80 can only be
 	guaranteed to have around a 1.19 cycle minimum for its actual access. I'm therefore further
@@ -373,7 +379,7 @@ class ConcreteMachine:
 
 		// MARK: - Chips.
 		CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
-		JustInTimeActor<Nick, HalfCycles, 40434603, 2840000> nick_; 
+		JustInTimeActor<Nick, HalfCycles, 40434603, 11360000> nick_;
 		bool previous_nick_interrupt_line_ = false;
 		// Cf. timing guesses above.
 };

From 6025516f9f49455935b5dabfa9fc5e1df73efc77 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 20 Jun 2021 14:31:02 -0400
Subject: [PATCH 052/117] Ensure addresses increment even when there's no
 target for pixels.

---
 Machines/Enterprise/Nick.cpp | 19 ++++++++++++++++++-
 Machines/Enterprise/Nick.hpp |  1 +
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 17fc34805..f8272c5fe 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -161,6 +161,8 @@ void Nick::run_for(Cycles duration) {
 
 				switch(mode_) {
 					default:
+						assert(false);
+					case Mode::Vsync:
 					break;
 
 					// NB: LSBALT/MSBALT and ALTIND0/ALTIND1 appear to have opposite effects on palette selection.
@@ -178,6 +180,9 @@ void Nick::run_for(Cycles duration) {
 
 						alt_ind_palettes[1] = alt_ind_palettes[0] + ((line_parameters_[2] & 0x40) ? 4 : 0);
 						alt_ind_palettes[3] = alt_ind_palettes[2] + ((line_parameters_[2] & 0x40) ? 4 : 0);
+
+						line_data_per_column_increments_[0] = 1 + (mode_ == Mode::Pixel);
+						line_data_per_column_increments_[1] = 0;
 					break;
 
 					case Mode::CH64:
@@ -192,6 +197,14 @@ void Nick::run_for(Cycles duration) {
 
 						alt_ind_palettes[1] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x80) ? 4 : 0);
 						alt_ind_palettes[3] = alt_ind_palettes[2] + ((line_parameters_[3] & 0x80) ? 4 : 0);
+
+						line_data_per_column_increments_[0] = 1;
+						line_data_per_column_increments_[1] = 0;
+					break;
+
+					case Mode::Attr:
+						line_data_per_column_increments_[0] = 1;
+						line_data_per_column_increments_[1] = 1;
 					break;
 				}
 			}
@@ -284,7 +297,10 @@ void Nick::run_for(Cycles duration) {
 								}
 								columns_remaining -= output_duration;
 							} else {
-								// TODO: advance line pointers.
+								// Ensure line data pointers are advanced as if there hadn't been back pressure on
+								// pixel rendering.
+								line_data_pointer_[0] += columns_remaining * line_data_per_column_increments_[0];
+								line_data_pointer_[1] += columns_remaining * line_data_per_column_increments_[1];
 
 								// Advance pixel pointer, so as to be able to supply something
 								// convincing to the CRT as to the number of samples that would have
@@ -518,6 +534,7 @@ template <int bpp, int index_bits> void Nick::output_character(uint16_t *target,
 		switch(bpp) {
 			default:
 				assert(false);
+				// TODO: other BPPs are supported for character modes, I think.
 			break;
 
 			case 1: {
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 31cf03be9..cb8f7431b 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -77,6 +77,7 @@ class Nick {
 		int bpp_ = 0;
 		int column_size_ = 0;
 		bool interrupt_line_ = true;
+		int line_data_per_column_increments_[2] = {0, 0};
 
 		// An accumulator for border output regions.
 		int border_duration_ = 0;

From d7ff6bd04d13c4da3e8842e35d7915e023a62fab Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 20 Jun 2021 20:30:54 -0400
Subject: [PATCH 053/117] Adds necessary declarations to install a DOS ROM.

---
 Analyser/Static/Enterprise/Target.hpp |  4 ++++
 Machines/Enterprise/Enterprise.cpp    | 30 +++++++++++++++++++++++++--
 Machines/Utility/ROMCatalogue.cpp     |  9 ++++++++
 Machines/Utility/ROMCatalogue.hpp     |  3 +++
 4 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/Analyser/Static/Enterprise/Target.hpp b/Analyser/Static/Enterprise/Target.hpp
index d758e4d6d..2a0fe11d4 100644
--- a/Analyser/Static/Enterprise/Target.hpp
+++ b/Analyser/Static/Enterprise/Target.hpp
@@ -20,17 +20,21 @@ namespace Enterprise {
 struct Target: public Analyser::Static::Target, public Reflection::StructImpl<Target> {
 	ReflectableEnum(EXOSVersion, v10, v20, v21, v23, Any);
 	ReflectableEnum(BASICVersion, v10, v11, v21, Any, None);
+	ReflectableEnum(DOS, EPDOS, EXDOS, None);
 
 	EXOSVersion exos_version = EXOSVersion::Any;
 	BASICVersion basic_version = BASICVersion::None;
+	DOS dos = DOS::None;
 
 	Target() : Analyser::Static::Target(Machine::Enterprise) {
 		if(needs_declare()) {
 			AnnounceEnum(EXOSVersion);
 			AnnounceEnum(BASICVersion);
+			AnnounceEnum(DOS);
 
 			DeclareField(exos_version);
 			DeclareField(basic_version);
+			DeclareField(dos);
 		}
 	}
 };
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index cb62888fd..ac01c39e2 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -60,7 +60,7 @@ namespace Enterprise {
 
 */
 
-class ConcreteMachine:
+template <bool has_disk_controller> class ConcreteMachine:
 	public CPU::Z80::BusHandler,
 	public Machine,
 	public MachineTypes::MappedKeyboardMachine,
@@ -122,6 +122,13 @@ class ConcreteMachine:
 				default: break;
 			}
 
+			// Possibly add in a DOS.
+			switch(target.dos) {
+				case Target::DOS::EPDOS:	request = request && ROM::Request(ROM::Name::EnterpriseEPDOS);	break;
+				case Target::DOS::EXDOS:	request = request && ROM::Request(ROM::Name::EnterpriseEXDOS);	break;
+				default: break;
+			}
+
 			// Get and validate ROMs.
 			auto roms = rom_fetcher(request);
 			if(!request.validate(roms)) {
@@ -158,6 +165,16 @@ class ConcreteMachine:
 				}
 			}
 
+			// Extract the appropriate DOS ROM.
+			dos_.fill(0xff);
+			for(const auto rom_name: { ROM::Name::EnterpriseEPDOS, ROM::Name::EnterpriseEXDOS }) {
+				const auto dos = roms.find(rom_name);
+				if(dos != roms.end()) {
+					memcpy(dos_.data(), dos->second.data(), std::min(dos_.size(), dos->second.size()));
+					break;
+				}
+			}
+
 			// Seed key state.
 			clear_all_keys();
 
@@ -291,6 +308,7 @@ class ConcreteMachine:
 		std::array<uint8_t, 64 * 1024> ram_;
 		std::array<uint8_t, 64 * 1024> exos_;
 		std::array<uint8_t, 16 * 1024> basic_;
+		std::array<uint8_t, 32 * 1024> dos_;
 		const uint8_t min_ram_slot_ = uint8_t(0x100 - (ram_.size() / 0x4000));
 
 		const uint8_t *read_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
@@ -310,6 +328,11 @@ class ConcreteMachine:
 				return;
 			}
 
+			if(offset >= 32 && offset < 32 + dos_.size() / 0x4000) {
+				page<slot>(&dos_[(offset - 32) * 0x4000], nullptr);
+				return;
+			}
+
 			// Of whatever size of RAM I've declared above, use only the final portion.
 			// This correlated with Nick always having been handed the final 64kb and,
 			// at least while the RAM is the first thing declared above, does a little
@@ -392,7 +415,10 @@ Machine *Machine::Enterprise(const Analyser::Static::Target *target, const ROMMa
 	using Target = Analyser::Static::Enterprise::Target;
 	const Target *const enterprise_target = dynamic_cast<const Target *>(target);
 
-	return new Enterprise::ConcreteMachine(*enterprise_target, rom_fetcher);
+	if(enterprise_target->dos != Target::DOS::None)
+		return new Enterprise::ConcreteMachine<false>(*enterprise_target, rom_fetcher);
+	else
+		return new Enterprise::ConcreteMachine<true>(*enterprise_target, rom_fetcher);
 }
 
 Machine::~Machine() {}
diff --git a/Machines/Utility/ROMCatalogue.cpp b/Machines/Utility/ROMCatalogue.cpp
index d245e98bb..acabcc591 100644
--- a/Machines/Utility/ROMCatalogue.cpp
+++ b/Machines/Utility/ROMCatalogue.cpp
@@ -458,6 +458,15 @@ Description::Description(Name name) {
 			*this = Description(name, "Enterprise", "the Enterprise BASIC ROM v2.1", filenames, 16 * 1024, crcs);
 		} break;
 
+		case Name::EnterpriseEPDOS: {
+			const std::initializer_list<std::string> filenames = {"epdos.bin", "EPDOS v1.7 (19xx)(Haluska, Laszlo).bin"};
+			*this = Description(name, "Enterprise", "the Enterprise EPDOS ROM", filenames, 32 * 1024, 0x201319ebu);
+		} break;
+		case Name::EnterpriseEXDOS: {
+			const std::initializer_list<std::string> filenames = {"exdos.bin", "EX-DOS EPROM (198x)(Enterprise).bin"};
+			*this = Description(name, "Enterprise", "the Enterprise EXOS ROM", filenames, 16 * 1024, 0xe6daa0e9u);
+		} break;
+
 		case Name::Macintosh128k:	*this = Description(name, "Macintosh", "the Macintosh 128k ROM", "mac128k.rom", 64*1024, 0x6d0c8a28u);	break;
 		case Name::Macintosh512k:	*this = Description(name, "Macintosh", "the Macintosh 512k ROM", "mac512k.rom", 64*1024, 0xcf759e0d);	break;
 		case Name::MacintoshPlus: {
diff --git a/Machines/Utility/ROMCatalogue.hpp b/Machines/Utility/ROMCatalogue.hpp
index 56b4e2c07..4f481f2e2 100644
--- a/Machines/Utility/ROMCatalogue.hpp
+++ b/Machines/Utility/ROMCatalogue.hpp
@@ -84,6 +84,9 @@ enum Name {
 	EnterpriseBASIC11Suffixed,
 	EnterpriseBASIC21,
 
+	EnterpriseEPDOS,
+	EnterpriseEXDOS,
+
 	// Macintosh.
 	Macintosh128k,
 	Macintosh512k,

From 954386f1ccaa5ba4a95e92af9703ce1f8176fc03 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 20 Jun 2021 20:50:23 -0400
Subject: [PATCH 054/117] Creates a shell for the disk-drive add-on card.

---
 Machines/Enterprise/EXDos.cpp      | 30 ++++++++++++++++++++++++++
 Machines/Enterprise/EXDos.hpp      | 34 ++++++++++++++++++++++++++++++
 Machines/Enterprise/Enterprise.cpp | 27 ++++++++++++++++++++++++
 3 files changed, 91 insertions(+)
 create mode 100644 Machines/Enterprise/EXDos.cpp
 create mode 100644 Machines/Enterprise/EXDos.hpp

diff --git a/Machines/Enterprise/EXDos.cpp b/Machines/Enterprise/EXDos.cpp
new file mode 100644
index 000000000..15d315df4
--- /dev/null
+++ b/Machines/Enterprise/EXDos.cpp
@@ -0,0 +1,30 @@
+//
+//  EXDos.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 20/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#include "EXDos.hpp"
+
+using namespace Enterprise;
+
+EXDos::EXDos() : WD1770(P1770) {
+//	emplace_drives(2, 8000000, 300, 2);
+	set_control_register(0x00);
+}
+
+void EXDos::set_disk(std::shared_ptr<Storage::Disk::Disk> disk, size_t drive) {
+}
+
+void EXDos::set_control_register(uint8_t control) {
+	last_control_ = control;
+}
+
+uint8_t EXDos::get_control_register() {
+	return last_control_;
+}
+
+void EXDos::set_motor_on(bool on) {
+}
diff --git a/Machines/Enterprise/EXDos.hpp b/Machines/Enterprise/EXDos.hpp
new file mode 100644
index 000000000..cc60a0033
--- /dev/null
+++ b/Machines/Enterprise/EXDos.hpp
@@ -0,0 +1,34 @@
+//
+//  EXDos.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 20/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#ifndef EXDos_hpp
+#define EXDos_hpp
+
+#include "../../Components/1770/1770.hpp"
+#include "../../Activity/Observer.hpp"
+
+namespace Enterprise {
+
+class EXDos final : public WD::WD1770 {
+	public:
+		EXDos();
+
+		void set_disk(std::shared_ptr<Storage::Disk::Disk> disk, size_t drive);
+
+		void set_control_register(uint8_t control);
+		uint8_t get_control_register();
+
+	private:
+		uint8_t last_control_ = 0;
+
+		void set_motor_on(bool on) override;
+};
+
+}
+
+#endif /* EXDos_hpp */
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index ac01c39e2..e29baf8fc 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -10,6 +10,7 @@
 
 #include "Keyboard.hpp"
 #include "Nick.hpp"
+#include "EXDos.hpp"
 
 #include "../MachineTypes.hpp"
 
@@ -208,6 +209,11 @@ template <bool has_disk_controller> class ConcreteMachine:
 				previous_nick_interrupt_line_ = nick_interrupt_line;
 			}
 
+			// The WD/etc runs at a nominal 8Mhz.
+			if constexpr (has_disk_controller) {
+				exdos_.run_for(Cycles(cycle.length.as_integral()));
+			}
+
 			switch(cycle.operation) {
 				default: break;
 
@@ -218,6 +224,15 @@ template <bool has_disk_controller> class ConcreteMachine:
 							assert(false);
 						break;
 
+						case 0x10:	case 0x11:	case 0x12:	case 0x13:
+						case 0x14:	case 0x15:	case 0x16:	case 0x17:
+							*cycle.value = exdos_.read(address);
+						break;
+						case 0x18:	case 0x19:	case 0x1a:	case 0x1b:
+						case 0x1c:	case 0x1d:	case 0x1e:	case 0x1f:
+							*cycle.value = exdos_.get_control_register();
+						break;
+
 						case 0xb0:	*cycle.value = pages_[0];	break;
 						case 0xb1:	*cycle.value = pages_[1];	break;
 						case 0xb2:	*cycle.value = pages_[2];	break;
@@ -243,6 +258,15 @@ template <bool has_disk_controller> class ConcreteMachine:
 							assert(false);
 						break;
 
+						case 0x10:	case 0x11:	case 0x12:	case 0x13:
+						case 0x14:	case 0x15:	case 0x16:	case 0x17:
+							exdos_.write(address, *cycle.value);
+						break;
+						case 0x18:	case 0x19:	case 0x1a:	case 0x1b:
+						case 0x1c:	case 0x1d:	case 0x1e:	case 0x1f:
+							 exdos_.set_control_register(*cycle.value);
+						break;
+
 						case 0x80:	case 0x81:	case 0x82:	case 0x83:
 						case 0x84:	case 0x85:	case 0x86:	case 0x87:
 						case 0x88:	case 0x89:	case 0x8a:	case 0x8b:
@@ -405,6 +429,9 @@ template <bool has_disk_controller> class ConcreteMachine:
 		JustInTimeActor<Nick, HalfCycles, 40434603, 11360000> nick_;
 		bool previous_nick_interrupt_line_ = false;
 		// Cf. timing guesses above.
+
+		// MARK: - EXDos card.
+		EXDos exdos_;
 };
 
 }

From b49cc407c6730ac9af4f012e34a80fef3b760beb Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 20 Jun 2021 22:30:27 -0400
Subject: [PATCH 055/117] Adds some guesses as to the EXDos expansion.

... with plenty left to do.
---
 Machines/Enterprise/EXDos.cpp                 | 31 +++++++++++++++++--
 Machines/Enterprise/Enterprise.cpp            | 17 +++++++++-
 .../Clock Signal.xcodeproj/project.pbxproj    |  8 +++++
 3 files changed, 53 insertions(+), 3 deletions(-)

diff --git a/Machines/Enterprise/EXDos.cpp b/Machines/Enterprise/EXDos.cpp
index 15d315df4..cec9c34e9 100644
--- a/Machines/Enterprise/EXDos.cpp
+++ b/Machines/Enterprise/EXDos.cpp
@@ -11,20 +11,47 @@
 using namespace Enterprise;
 
 EXDos::EXDos() : WD1770(P1770) {
-//	emplace_drives(2, 8000000, 300, 2);
+	emplace_drives(4, 8000000, 300, 2);
 	set_control_register(0x00);
 }
 
 void EXDos::set_disk(std::shared_ptr<Storage::Disk::Disk> disk, size_t drive) {
+	get_drive(drive).set_disk(disk);
 }
 
 void EXDos::set_control_register(uint8_t control) {
+	printf("Control: %02x\n", control);
+
 	last_control_ = control;
+
+	// Set side.
+	const int head = (control >> 4) & 1;
+	for(size_t c = 0; c < 4; c++) {
+		get_drive(c).set_head(head);
+	}
+
+	// Select drive.
+	// TODO: should potentially be drives, plural.
+	set_drive(0);
+	for(int c = 1; c < 4; c++) {
+		if(control & (1 << c)) {
+			set_drive(c);
+		}
+	}
+
+	// TODO: seems like bit 6 might be connected to the drive's RDY line?
+
+	// TODO: does part of this register select double/single density mode?
+	// Probably either bit 5 or bit 7 of the control register?
+	set_is_double_density(true);
 }
 
 uint8_t EXDos::get_control_register() {
-	return last_control_;
+	return last_control_ | (get_drive().get_is_ready() ? 0x40 : 0x00);
 }
 
 void EXDos::set_motor_on(bool on) {
+	// TODO: this status should transfer if the selected drive changes. But the same goes for
+	// writing state, so plenty of work to do in general here.
+	get_drive().set_motor_on(on);
 }
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index e29baf8fc..cd5dd6188 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -65,6 +65,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 	public CPU::Z80::BusHandler,
 	public Machine,
 	public MachineTypes::MappedKeyboardMachine,
+	public MachineTypes::MediaTarget,
 	public MachineTypes::ScanProducer,
 	public MachineTypes::TimedMachine {
 	public:
@@ -190,6 +191,9 @@ template <bool has_disk_controller> class ConcreteMachine:
 			page<1>(0x00);
 			page<2>(0x00);
 			page<3>(0x00);
+
+			// Pass on any media.
+			insert_media(target.media);
 		}
 
 		// MARK: - Z80::BusHandler.
@@ -410,6 +414,17 @@ template <bool has_disk_controller> class ConcreteMachine:
 			key_lines_.fill(0xff);
 		}
 
+		// MARK: - MediaTarget
+		bool insert_media(const Analyser::Static::Media &media) final {
+			if constexpr (has_disk_controller) {
+				if(!media.disks.empty()) {
+					exdos_.set_disk(media.disks.front(), 0);
+				}
+			}
+
+			return true;
+		}
+
 		// MARK: - Interrupts
 		enum class Interrupt: uint8_t {
 			Nick = 0x20
@@ -442,7 +457,7 @@ Machine *Machine::Enterprise(const Analyser::Static::Target *target, const ROMMa
 	using Target = Analyser::Static::Enterprise::Target;
 	const Target *const enterprise_target = dynamic_cast<const Target *>(target);
 
-	if(enterprise_target->dos != Target::DOS::None)
+	if(enterprise_target->dos == Target::DOS::None)
 		return new Enterprise::ConcreteMachine<false>(*enterprise_target, rom_fetcher);
 	else
 		return new Enterprise::ConcreteMachine<true>(*enterprise_target, rom_fetcher);
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index 127657d64..c55e0ded8 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -26,6 +26,8 @@
 		4B051CB0267C1CA200CA44E8 /* Keyboard.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */; };
 		4B051CB1267C1CA200CA44E8 /* Keyboard.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */; };
 		4B051CB3267D3FF800CA44E8 /* EnterpriseNickTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CB2267D3FF800CA44E8 /* EnterpriseNickTests.mm */; };
+		4B051CB62680158600CA44E8 /* EXDos.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CB42680158600CA44E8 /* EXDos.cpp */; };
+		4B051CB72680158600CA44E8 /* EXDos.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B051CB42680158600CA44E8 /* EXDos.cpp */; };
 		4B05401E219D1618001BF69C /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B05401D219D1618001BF69C /* ScanTarget.cpp */; };
 		4B05401F219D1618001BF69C /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B05401D219D1618001BF69C /* ScanTarget.cpp */; };
 		4B055A7A1FAE78A00060FFFF /* SDL2.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 4B055A771FAE78210060FFFF /* SDL2.framework */; };
@@ -1047,6 +1049,8 @@
 		4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = Keyboard.cpp; sourceTree = "<group>"; };
 		4B051CAF267C1CA200CA44E8 /* Keyboard.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Keyboard.hpp; sourceTree = "<group>"; };
 		4B051CB2267D3FF800CA44E8 /* EnterpriseNickTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = EnterpriseNickTests.mm; sourceTree = "<group>"; };
+		4B051CB42680158600CA44E8 /* EXDos.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = EXDos.cpp; sourceTree = "<group>"; };
+		4B051CB52680158600CA44E8 /* EXDos.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = EXDos.hpp; sourceTree = "<group>"; };
 		4B05401D219D1618001BF69C /* ScanTarget.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = ScanTarget.cpp; sourceTree = "<group>"; };
 		4B055A6A1FAE763F0060FFFF /* Clock Signal Kiosk */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = "Clock Signal Kiosk"; sourceTree = BUILT_PRODUCTS_DIR; };
 		4B055A771FAE78210060FFFF /* SDL2.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = SDL2.framework; path = ../../../../Library/Frameworks/SDL2.framework; sourceTree = SOURCE_ROOT; };
@@ -2113,9 +2117,11 @@
 			isa = PBXGroup;
 			children = (
 				4B051CA12676F52200CA44E8 /* Enterprise.cpp */,
+				4B051CB42680158600CA44E8 /* EXDos.cpp */,
 				4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */,
 				4B051CAA26783E2000CA44E8 /* Nick.cpp */,
 				4B051CA02676F52200CA44E8 /* Enterprise.hpp */,
+				4B051CB52680158600CA44E8 /* EXDos.hpp */,
 				4B051CAF267C1CA200CA44E8 /* Keyboard.hpp */,
 				4B051CAB26783E2000CA44E8 /* Nick.hpp */,
 			);
@@ -5295,6 +5301,7 @@
 				4BC131712346DE5000E4FF3D /* StaticAnalyser.cpp in Sources */,
 				4B055ACA1FAE9AFB0060FFFF /* Vic20.cpp in Sources */,
 				4BE21200253FC80900435408 /* StaticAnalyser.cpp in Sources */,
+				4B051CB72680158600CA44E8 /* EXDos.cpp in Sources */,
 				4B8318B222D3E53C006DB630 /* Video.cpp in Sources */,
 				4B055ABC1FAE86170060FFFF /* ZX8081.cpp in Sources */,
 				4B055AC91FAE9AFB0060FFFF /* Keyboard.cpp in Sources */,
@@ -5601,6 +5608,7 @@
 				4BFDD78C1F7F2DB4008579B9 /* ImplicitSectors.cpp in Sources */,
 				4B894526201967B4007DE474 /* StaticAnalyser.cpp in Sources */,
 				4BEE0A6F1D72496600532C7B /* Cartridge.cpp in Sources */,
+				4B051CB62680158600CA44E8 /* EXDos.cpp in Sources */,
 				4B8805FB1DCFF807003085B1 /* Oric.cpp in Sources */,
 				4B6ED2F0208E2F8A0047B343 /* WOZ.cpp in Sources */,
 				4B15A9FC208249BB005E6C8D /* StaticAnalyser.cpp in Sources */,

From 117f9a9794237e4779c28b8e3e62a3b9a3845323 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 21 Jun 2021 07:31:58 -0400
Subject: [PATCH 056/117] Adds notes on intended meaning of status register.

---
 Machines/Enterprise/EXDos.cpp      | 41 ++++++++++++++++++++++--------
 Machines/Enterprise/EXDos.hpp      |  2 +-
 Machines/Enterprise/Enterprise.cpp |  2 +-
 3 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/Machines/Enterprise/EXDos.cpp b/Machines/Enterprise/EXDos.cpp
index cec9c34e9..189a18468 100644
--- a/Machines/Enterprise/EXDos.cpp
+++ b/Machines/Enterprise/EXDos.cpp
@@ -17,12 +17,30 @@ EXDos::EXDos() : WD1770(P1770) {
 
 void EXDos::set_disk(std::shared_ptr<Storage::Disk::Disk> disk, size_t drive) {
 	get_drive(drive).set_disk(disk);
+	disk_did_change_ = true;
 }
 
-void EXDos::set_control_register(uint8_t control) {
-	printf("Control: %02x\n", control);
+// Documentation for the control register:
+//
+//	Write:
+//		b7	in use				(???)
+//		b6	disk change reset
+//		b5	0 = double density, 1 = single density
+//		b4	side 1 select
+//		b3, b3, b1, b0	select drive 3, 2, 1, 0
+//
+//	Read:
+//		b7 data request from WD1770
+//		b6 disk change
+//		b5, b4, b3, b2: not used
+//		b1 interrupt request from WD1770
+//		b0 drive ready
 
-	last_control_ = control;
+void EXDos::set_control_register(uint8_t control) {
+	printf("Set control: %02x\n", control);
+
+	if(control & 0x40) disk_did_change_ = false;
+	set_is_double_density(!(control & 0x20));
 
 	// Set side.
 	const int head = (control >> 4) & 1;
@@ -38,16 +56,19 @@ void EXDos::set_control_register(uint8_t control) {
 			set_drive(c);
 		}
 	}
-
-	// TODO: seems like bit 6 might be connected to the drive's RDY line?
-
-	// TODO: does part of this register select double/single density mode?
-	// Probably either bit 5 or bit 7 of the control register?
-	set_is_double_density(true);
 }
 
 uint8_t EXDos::get_control_register() {
-	return last_control_ | (get_drive().get_is_ready() ? 0x40 : 0x00);
+	// TODO: how does disk_did_change_ really work? Presumably
+	// it latches RDY?
+	const uint8_t status =
+		(get_data_request_line() ? 0x80 : 0x00) |
+		(disk_did_change_ ? 0x40 : 0x00) |
+		(get_interrupt_request_line() ? 0x02 : 0x00) |
+		(get_drive().get_is_ready() ? 0x01 : 0x00);
+
+	printf("Get status: %02x\n", status);
+	return status;
 }
 
 void EXDos::set_motor_on(bool on) {
diff --git a/Machines/Enterprise/EXDos.hpp b/Machines/Enterprise/EXDos.hpp
index cc60a0033..42d8f81c1 100644
--- a/Machines/Enterprise/EXDos.hpp
+++ b/Machines/Enterprise/EXDos.hpp
@@ -24,7 +24,7 @@ class EXDos final : public WD::WD1770 {
 		uint8_t get_control_register();
 
 	private:
-		uint8_t last_control_ = 0;
+		bool disk_did_change_ = false;
 
 		void set_motor_on(bool on) override;
 };
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index cd5dd6188..ee0a598e4 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -287,7 +287,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 						case 0xa4:	case 0xa5:	case 0xa6:	case 0xa7:
 						case 0xa8:	case 0xa9:	case 0xaa:	case 0xab:
 						case 0xac:	case 0xad:	case 0xae:	case 0xaf:
-							printf("TODO: audio adjust %04x <- %02x\n", address, *cycle.value);
+//							printf("TODO: audio adjust %04x <- %02x\n", address, *cycle.value);
 						break;
 
 						case 0xb4:

From c1678d7be70c4f1f4662c47e3ec41dfa3b151d75 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 21 Jun 2021 22:56:25 -0400
Subject: [PATCH 057/117] Corrects exposition and transmission of drive
 selection.

What a klutz I've been.
---
 Machines/Enterprise/EXDos.cpp              | 8 +-------
 Storage/Disk/Controller/DiskController.hpp | 6 ++++--
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/Machines/Enterprise/EXDos.cpp b/Machines/Enterprise/EXDos.cpp
index 189a18468..4dda5cf17 100644
--- a/Machines/Enterprise/EXDos.cpp
+++ b/Machines/Enterprise/EXDos.cpp
@@ -49,13 +49,7 @@ void EXDos::set_control_register(uint8_t control) {
 	}
 
 	// Select drive.
-	// TODO: should potentially be drives, plural.
-	set_drive(0);
-	for(int c = 1; c < 4; c++) {
-		if(control & (1 << c)) {
-			set_drive(c);
-		}
-	}
+	set_drive(control & 0xf);
 }
 
 uint8_t EXDos::get_control_register() {
diff --git a/Storage/Disk/Controller/DiskController.hpp b/Storage/Disk/Controller/DiskController.hpp
index 3d8c723c3..55f7dcc5c 100644
--- a/Storage/Disk/Controller/DiskController.hpp
+++ b/Storage/Disk/Controller/DiskController.hpp
@@ -49,8 +49,10 @@ class Controller:
 		void run_for(const Cycles cycles);
 
 		/*!
-			Sets the current drive(s). Normally this will be exactly one, but some machines allow
-			zero or multiple drives to be attached, with useless results.
+			Sets the current drive(s), by bit mask. Normally this will be exactly one, but some
+			machines allow zero or multiple drives to be attached, with useless results.
+
+			E.g. supply 1 to select drive 0, 2 to select drive 1, 4 to select drive 2, etc.
 		*/
 		void set_drive(int index_mask);
 

From 69c07349753d17775c9e097b459523525eb9b6ca Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 21 Jun 2021 23:26:55 -0400
Subject: [PATCH 058/117] WD1770: switch motor on even if spin-up is disabled.

---
 Components/1770/1770.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/Components/1770/1770.cpp b/Components/1770/1770.cpp
index 2845155cd..28c9d5e72 100644
--- a/Components/1770/1770.cpp
+++ b/Components/1770/1770.cpp
@@ -276,7 +276,10 @@ void WD1770::posit_event(int new_event_type) {
 		goto test_type1_type;
 
 	begin_type1_spin_up:
-		if((command_&0x08) || get_drive().get_motor_on()) goto test_type1_type;
+		if((command_&0x08) || get_drive().get_motor_on()) {
+			set_motor_on(true);
+			goto test_type1_type;
+		}
 		SPIN_UP();
 
 	test_type1_type:
@@ -387,7 +390,10 @@ void WD1770::posit_event(int new_event_type) {
 		distance_into_section_ = 0;
 
 		if((command_&0x08) && has_motor_on_line()) goto test_type2_delay;
-		if(!has_motor_on_line() && !has_head_load_line()) goto test_type2_delay;
+		if(!has_motor_on_line() && !has_head_load_line()) {
+			if(has_motor_on_line()) set_motor_on(true);
+			goto test_type2_delay;
+		}
 
 		if(has_motor_on_line()) goto begin_type2_spin_up;
 		goto begin_type2_load_head;

From 3acd0be1f7c18ccd96cbcc8ebaeef3230cbbb2a9 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 21 Jun 2021 23:27:13 -0400
Subject: [PATCH 059/117] Copy and paste 2bpp character support.

---
 Machines/Enterprise/Nick.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index f8272c5fe..6eb188ab7 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -550,6 +550,15 @@ template <int bpp, int index_bits> void Nick::output_character(uint16_t *target,
 				target[7] = palette[(pixels & 0x01) >> 0];
 				target += 8;
 			} break;
+
+			case 2:
+				target[0] = palette_[((pixels & 0x80) >> 6) | ((pixels & 0x08) >> 3)];
+				target[1] = palette_[((pixels & 0x40) >> 5) | ((pixels & 0x04) >> 2)];
+				target[2] = palette_[((pixels & 0x20) >> 4) | ((pixels & 0x02) >> 1)];
+				target[3] = palette_[((pixels & 0x10) >> 3) | ((pixels & 0x01) >> 0)];
+
+				target += 4;
+			break;
 		}
 	}
 }

From e0627809688b24932f5a2eac6f8386b9a88fe5ec Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 22 Jun 2021 06:15:42 -0400
Subject: [PATCH 060/117] Extends back to 128kb and stops halting on
 unrecognised ports.

---
 Machines/Enterprise/EXDos.cpp      | 4 ++--
 Machines/Enterprise/Enterprise.cpp | 7 ++++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/Machines/Enterprise/EXDos.cpp b/Machines/Enterprise/EXDos.cpp
index 4dda5cf17..ec7673407 100644
--- a/Machines/Enterprise/EXDos.cpp
+++ b/Machines/Enterprise/EXDos.cpp
@@ -37,7 +37,7 @@ void EXDos::set_disk(std::shared_ptr<Storage::Disk::Disk> disk, size_t drive) {
 //		b0 drive ready
 
 void EXDos::set_control_register(uint8_t control) {
-	printf("Set control: %02x\n", control);
+//	printf("Set control: %02x\n", control);
 
 	if(control & 0x40) disk_did_change_ = false;
 	set_is_double_density(!(control & 0x20));
@@ -61,7 +61,7 @@ uint8_t EXDos::get_control_register() {
 		(get_interrupt_request_line() ? 0x02 : 0x00) |
 		(get_drive().get_is_ready() ? 0x01 : 0x00);
 
-	printf("Get status: %02x\n", status);
+//	printf("Get status: %02x\n", status);
 	return status;
 }
 
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index ee0a598e4..1ba476c84 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -225,7 +225,8 @@ template <bool has_disk_controller> class ConcreteMachine:
 					switch(address & 0xff) {
 						default:
 							printf("Unhandled input: %04x\n", address);
-							assert(false);
+//							assert(false);
+							*cycle.value = 0xff;
 						break;
 
 						case 0x10:	case 0x11:	case 0x12:	case 0x13:
@@ -259,7 +260,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 					switch(address & 0xff) {
 						default:
 							printf("Unhandled output: %04x\n", address);
-							assert(false);
+//							assert(false);
 						break;
 
 						case 0x10:	case 0x11:	case 0x12:	case 0x13:
@@ -333,7 +334,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 
 	private:
 		// MARK: - Memory layout
-		std::array<uint8_t, 64 * 1024> ram_;
+		std::array<uint8_t, 128 * 1024> ram_;
 		std::array<uint8_t, 64 * 1024> exos_;
 		std::array<uint8_t, 16 * 1024> basic_;
 		std::array<uint8_t, 32 * 1024> dos_;

From 83a54fd6d22d4fd42251106e3807848e57a3b4a4 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 22 Jun 2021 06:54:17 -0400
Subject: [PATCH 061/117] Use the FAT12 boot sector to determine geometry.

---
 Analyser/Static/StaticAnalyser.cpp            |  6 +-
 .../Clock Signal.xcodeproj/project.pbxproj    | 20 +++----
 Storage/Disk/DiskImage/Formats/FAT12.cpp      | 57 ++++++++++++++++++
 .../Formats/{MSXDSK.hpp => FAT12.hpp}         | 10 ++--
 Storage/Disk/DiskImage/Formats/MSXDSK.cpp     | 59 -------------------
 5 files changed, 76 insertions(+), 76 deletions(-)
 create mode 100644 Storage/Disk/DiskImage/Formats/FAT12.cpp
 rename Storage/Disk/DiskImage/Formats/{MSXDSK.hpp => FAT12.hpp} (73%)
 delete mode 100644 Storage/Disk/DiskImage/Formats/MSXDSK.cpp

diff --git a/Analyser/Static/StaticAnalyser.cpp b/Analyser/Static/StaticAnalyser.cpp
index 016869b1e..e145e8345 100644
--- a/Analyser/Static/StaticAnalyser.cpp
+++ b/Analyser/Static/StaticAnalyser.cpp
@@ -43,9 +43,9 @@
 #include "../../Storage/Disk/DiskImage/Formats/MacintoshIMG.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/G64.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/DMK.hpp"
+#include "../../Storage/Disk/DiskImage/Formats/FAT12.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/HFE.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/MSA.hpp"
-#include "../../Storage/Disk/DiskImage/Formats/MSXDSK.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/NIB.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/OricMFMDSK.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/SSD.hpp"
@@ -147,7 +147,7 @@ static Media GetMediaAndPlatforms(const std::string &file_name, TargetPlatform::
 	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::MacintoshIMG>, TargetPlatform::Macintosh)	// DSK (Macintosh, floppy disk)
 	Format("dsk", result.mass_storage_devices, MassStorage::HFV, TargetPlatform::Macintosh)						// DSK (Macintosh, hard disk, single volume image)
 	Format("dsk", result.mass_storage_devices, MassStorage::DSK, TargetPlatform::Macintosh)						// DSK (Macintosh, hard disk, full device image)
-	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::MSXDSK>, TargetPlatform::MSX)				// DSK (MSX)
+	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::FAT12>, TargetPlatform::MSX)				// DSK (MSX)
 	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::OricMFMDSK>, TargetPlatform::Oric)			// DSK (Oric)
 	Format("g64", result.disks, Disk::DiskImageHolder<Storage::Disk::G64>, TargetPlatform::Commodore)			// G64
 	Format(	"hfe",
@@ -157,7 +157,7 @@ static Media GetMediaAndPlatforms(const std::string &file_name, TargetPlatform::
 			// HFE (TODO: switch to AllDisk once the MSX stops being so greedy)
 	Format("img", result.disks, Disk::DiskImageHolder<Storage::Disk::MacintoshIMG>, TargetPlatform::Macintosh)		// IMG (DiskCopy 4.2)
 	Format("image", result.disks, Disk::DiskImageHolder<Storage::Disk::MacintoshIMG>, TargetPlatform::Macintosh)	// IMG (DiskCopy 4.2)
-	Format("img", result.disks, Disk::DiskImageHolder<Storage::Disk::MSXDSK>, TargetPlatform::Enterprise)		// IMG (Enterprise/MS-DOS style)
+	Format("img", result.disks, Disk::DiskImageHolder<Storage::Disk::FAT12>, TargetPlatform::Enterprise)		// IMG (Enterprise/MS-DOS style)
 	Format("msa", result.disks, Disk::DiskImageHolder<Storage::Disk::MSA>, TargetPlatform::AtariST)				// MSA
 	Format("nib", result.disks, Disk::DiskImageHolder<Storage::Disk::NIB>, TargetPlatform::DiskII)				// NIB
 	Format("o", result.tapes, Tape::ZX80O81P, TargetPlatform::ZX8081)											// O
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index c55e0ded8..ff6cbeb57 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -323,7 +323,7 @@
 		4B778F0023A5EB990000D260 /* G64.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B4518931F75FD1B00926311 /* G64.cpp */; };
 		4B778F0123A5EBA00000D260 /* MacintoshIMG.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BB4BFAE22A42F290069048D /* MacintoshIMG.cpp */; };
 		4B778F0223A5EBA40000D260 /* MFMSectorDump.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B58601C1F806AB200AEE2E3 /* MFMSectorDump.cpp */; };
-		4B778F0323A5EBB00000D260 /* MSXDSK.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* MSXDSK.cpp */; };
+		4B778F0323A5EBB00000D260 /* FAT12.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* FAT12.cpp */; };
 		4B778F0423A5EBB00000D260 /* OricMFMDSK.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B4518971F75FD1B00926311 /* OricMFMDSK.cpp */; };
 		4B778F0523A5EBB00000D260 /* ST.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BE0A3EC237BB170002AB46F /* ST.cpp */; };
 		4B778F0623A5EC150000D260 /* CAS.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B0E04E81FC9E5DA00F43484 /* CAS.cpp */; };
@@ -961,8 +961,8 @@
 		4BE9A6B11EDE293000CBCB47 /* zexdoc.com in Resources */ = {isa = PBXBuildFile; fileRef = 4BE9A6B01EDE293000CBCB47 /* zexdoc.com */; };
 		4BEA525E1DF33323007E74F2 /* Tape.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEA525D1DF33323007E74F2 /* Tape.cpp */; };
 		4BEA52631DF339D7007E74F2 /* SoundGenerator.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEA52611DF339D7007E74F2 /* SoundGenerator.cpp */; };
-		4BEBFB4D2002C4BF000708CC /* MSXDSK.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* MSXDSK.cpp */; };
-		4BEBFB4E2002C4BF000708CC /* MSXDSK.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* MSXDSK.cpp */; };
+		4BEBFB4D2002C4BF000708CC /* FAT12.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* FAT12.cpp */; };
+		4BEBFB4E2002C4BF000708CC /* FAT12.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4B2002C4BF000708CC /* FAT12.cpp */; };
 		4BEBFB512002DB30000708CC /* DiskROM.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4F2002DB30000708CC /* DiskROM.cpp */; };
 		4BEBFB522002DB30000708CC /* DiskROM.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEBFB4F2002DB30000708CC /* DiskROM.cpp */; };
 		4BEDA3BA25B25563000C2DBD /* Decoder.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BEDA3B425B25563000C2DBD /* Decoder.cpp */; };
@@ -2021,8 +2021,8 @@
 		4BEA52601DF3343A007E74F2 /* Interrupts.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Interrupts.hpp; sourceTree = "<group>"; };
 		4BEA52611DF339D7007E74F2 /* SoundGenerator.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = SoundGenerator.cpp; sourceTree = "<group>"; };
 		4BEA52621DF339D7007E74F2 /* SoundGenerator.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = SoundGenerator.hpp; sourceTree = "<group>"; };
-		4BEBFB4B2002C4BF000708CC /* MSXDSK.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = MSXDSK.cpp; sourceTree = "<group>"; };
-		4BEBFB4C2002C4BF000708CC /* MSXDSK.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = MSXDSK.hpp; sourceTree = "<group>"; };
+		4BEBFB4B2002C4BF000708CC /* FAT12.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = FAT12.cpp; sourceTree = "<group>"; };
+		4BEBFB4C2002C4BF000708CC /* FAT12.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = FAT12.hpp; sourceTree = "<group>"; };
 		4BEBFB4F2002DB30000708CC /* DiskROM.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = DiskROM.cpp; sourceTree = "<group>"; };
 		4BEBFB502002DB30000708CC /* DiskROM.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = DiskROM.hpp; sourceTree = "<group>"; };
 		4BEDA3B425B25563000C2DBD /* Decoder.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = Decoder.cpp; sourceTree = "<group>"; };
@@ -2713,7 +2713,7 @@
 				4BB4BFAE22A42F290069048D /* MacintoshIMG.cpp */,
 				4B58601C1F806AB200AEE2E3 /* MFMSectorDump.cpp */,
 				4BC131782346DF2B00E4FF3D /* MSA.cpp */,
-				4BEBFB4B2002C4BF000708CC /* MSXDSK.cpp */,
+				4BEBFB4B2002C4BF000708CC /* FAT12.cpp */,
 				4B0F94FC208C1A1600FE41D9 /* NIB.cpp */,
 				4B4518971F75FD1B00926311 /* OricMFMDSK.cpp */,
 				4B4518991F75FD1B00926311 /* SSD.cpp */,
@@ -2730,7 +2730,7 @@
 				4BB4BFAF22A42F290069048D /* MacintoshIMG.hpp */,
 				4B58601D1F806AB200AEE2E3 /* MFMSectorDump.hpp */,
 				4BC131792346DF2B00E4FF3D /* MSA.hpp */,
-				4BEBFB4C2002C4BF000708CC /* MSXDSK.hpp */,
+				4BEBFB4C2002C4BF000708CC /* FAT12.hpp */,
 				4B0F94FD208C1A1600FE41D9 /* NIB.hpp */,
 				4B4518981F75FD1B00926311 /* OricMFMDSK.hpp */,
 				4B45189A1F75FD1B00926311 /* SSD.hpp */,
@@ -5283,7 +5283,7 @@
 				4BB4BFBA22A4372F0069048D /* StaticAnalyser.cpp in Sources */,
 				4B055AA21FAE85DA0060FFFF /* SSD.cpp in Sources */,
 				4B2E86E325DC95150024F1E9 /* Joystick.cpp in Sources */,
-				4BEBFB4E2002C4BF000708CC /* MSXDSK.cpp in Sources */,
+				4BEBFB4E2002C4BF000708CC /* FAT12.cpp in Sources */,
 				4B055ADD1FAE9B460060FFFF /* i8272.cpp in Sources */,
 				4B055A9C1FAE85DA0060FFFF /* CPCDSK.cpp in Sources */,
 				4B2BF19223DCC6A800C3AD60 /* STX.cpp in Sources */,
@@ -5597,7 +5597,7 @@
 				4B894536201967B4007DE474 /* Z80.cpp in Sources */,
 				4BCA6CC81D9DD9F000C2D7B2 /* CommodoreROM.cpp in Sources */,
 				4BC1317A2346DF2B00E4FF3D /* MSA.cpp in Sources */,
-				4BEBFB4D2002C4BF000708CC /* MSXDSK.cpp in Sources */,
+				4BEBFB4D2002C4BF000708CC /* FAT12.cpp in Sources */,
 				4BBFBB6C1EE8401E00C01E7A /* ZX8081.cpp in Sources */,
 				4B83348A1F5DB94B0097E338 /* IRQDelegatePortHandler.cpp in Sources */,
 				4B8DD3862634D37E00B3C866 /* SNA.cpp in Sources */,
@@ -5745,7 +5745,7 @@
 				4B3BA0CF1D318B44005DD7A7 /* MOS6522Bridge.mm in Sources */,
 				4B778F6023A5F3460000D260 /* Disk.cpp in Sources */,
 				4B778F5C23A5F3070000D260 /* MSX.cpp in Sources */,
-				4B778F0323A5EBB00000D260 /* MSXDSK.cpp in Sources */,
+				4B778F0323A5EBB00000D260 /* FAT12.cpp in Sources */,
 				4B778F4023A5F1910000D260 /* z8530.cpp in Sources */,
 				4B778EFD23A5EB8E0000D260 /* AppleDSK.cpp in Sources */,
 				4B778EFB23A5EB7E0000D260 /* HFE.cpp in Sources */,
diff --git a/Storage/Disk/DiskImage/Formats/FAT12.cpp b/Storage/Disk/DiskImage/Formats/FAT12.cpp
new file mode 100644
index 000000000..ebdb1b8bf
--- /dev/null
+++ b/Storage/Disk/DiskImage/Formats/FAT12.cpp
@@ -0,0 +1,57 @@
+//
+//  FAT12.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 07/01/2018.
+//  Copyright 2018 Thomas Harte. All rights reserved.
+//
+
+#include "FAT12.hpp"
+
+#include "Utility/ImplicitSectors.hpp"
+
+using namespace Storage::Disk;
+
+FAT12::FAT12(const std::string &file_name) :
+	MFMSectorDump(file_name) {
+	// The only sanity check here is whether a sensible
+	// geometry is encoded in the first sector, or can be guessed.
+	off_t file_size = file_.stats().st_size;
+
+	if(file_size < 512) throw Error::InvalidFormat;
+
+	// Inspect the FAT.
+	file_.seek(11, SEEK_SET);
+	sector_size_ = file_.get16le();
+	file_.seek(19, SEEK_SET);
+	const uint16_t total_sectors = file_.get16le();
+	file_.seek(24, SEEK_SET);
+	sector_count_ = file_.get16le();
+	head_count_ = file_.get16le();
+
+	// Throw if there would seemingly be an incomplete track.
+	if(file_size != total_sectors*sector_size_) throw Error::InvalidFormat;
+	if(total_sectors % (head_count_ * sector_count_)) throw Error::InvalidFormat;
+	track_count_ = int(total_sectors / (head_count_ * sector_count_));
+
+	// Check that there is a valid power-of-two sector size.
+	uint8_t log_sector_size = 2;
+	while(log_sector_size < 5 && (1 << (7+log_sector_size)) != sector_size_) {
+		++log_sector_size;
+	}
+	if(log_sector_size >= 5) throw Error::InvalidFormat;
+
+	set_geometry(sector_count_, log_sector_size, 1, true);
+}
+
+HeadPosition FAT12::get_maximum_head_position() {
+	return HeadPosition(track_count_);
+}
+
+int FAT12::get_head_count() {
+	return head_count_;
+}
+
+long FAT12::get_file_offset_for_position(Track::Address address) {
+	return (address.position.as_int()*head_count_ + address.head) * sector_size_ * sector_count_;
+}
diff --git a/Storage/Disk/DiskImage/Formats/MSXDSK.hpp b/Storage/Disk/DiskImage/Formats/FAT12.hpp
similarity index 73%
rename from Storage/Disk/DiskImage/Formats/MSXDSK.hpp
rename to Storage/Disk/DiskImage/Formats/FAT12.hpp
index f88c46754..044612466 100644
--- a/Storage/Disk/DiskImage/Formats/MSXDSK.hpp
+++ b/Storage/Disk/DiskImage/Formats/FAT12.hpp
@@ -1,5 +1,5 @@
 //
-//  MSXDSK.hpp
+//  FAT12.hpp
 //  Clock Signal
 //
 //  Created by Thomas Harte on 07/01/2018.
@@ -17,12 +17,12 @@ namespace Storage {
 namespace Disk {
 
 /*!
-	Provides a @c DiskImage describing an MSDOS-style disk image:
+	Provides a @c DiskImage holding an MSDOS-style FAT12 disk image:
 	a sector dump of appropriate proportions.
 */
-class MSXDSK: public MFMSectorDump {
+class FAT12: public MFMSectorDump {
 	public:
-		MSXDSK(const std::string &file_name);
+		FAT12(const std::string &file_name);
 		HeadPosition get_maximum_head_position() final;
 		int get_head_count() final;
 
@@ -31,6 +31,8 @@ class MSXDSK: public MFMSectorDump {
 
 		int head_count_;
 		int track_count_;
+		int sector_count_;
+		int sector_size_;
 };
 
 }
diff --git a/Storage/Disk/DiskImage/Formats/MSXDSK.cpp b/Storage/Disk/DiskImage/Formats/MSXDSK.cpp
deleted file mode 100644
index f811a3599..000000000
--- a/Storage/Disk/DiskImage/Formats/MSXDSK.cpp
+++ /dev/null
@@ -1,59 +0,0 @@
-//
-//  MSXDSK.cpp
-//  Clock Signal
-//
-//  Created by Thomas Harte on 07/01/2018.
-//  Copyright 2018 Thomas Harte. All rights reserved.
-//
-
-#include "MSXDSK.hpp"
-
-#include "Utility/ImplicitSectors.hpp"
-
-namespace {
-	constexpr int sectors_per_track = 9;
-	constexpr int sector_size = 2;
-	constexpr off_t track_size = (128 << sector_size)*sectors_per_track;
-}
-
-using namespace Storage::Disk;
-
-MSXDSK::MSXDSK(const std::string &file_name) :
-	MFMSectorDump(file_name) {
-	// The only sanity check here is whether a sensible
-	// geometry can be guessed.
-	off_t file_size = file_.stats().st_size;
-
-	// Throw if there would seemingly be an incomplete track.
-	if(file_size % track_size) throw Error::InvalidFormat;
-
-	track_count_ = int(file_size / track_size);
-	head_count_ = 1;
-
-	// Throw if too large or too small or too large for single sided and
-	// clearly not double sided.
-	if(track_count_ < 40) throw Error::InvalidFormat;
-	if(track_count_ > 82*2) throw Error::InvalidFormat;
-	if(track_count_ > 82 && track_count_&1) throw Error::InvalidFormat;
-
-	// The below effectively prefers the idea of a single-sided 80-track disk
-	// to a double-sided 40-track disk. Emulators have to guess.
-	if(track_count_ > 82) {
-		track_count_ /= 2;
-		head_count_ = 2;
-	}
-
-	set_geometry(sectors_per_track, sector_size, 1, true);
-}
-
-HeadPosition MSXDSK::get_maximum_head_position() {
-	return HeadPosition(track_count_);
-}
-
-int MSXDSK::get_head_count() {
-	return head_count_;
-}
-
-long MSXDSK::get_file_offset_for_position(Track::Address address) {
-	return (address.position.as_int()*head_count_ + address.head) * 512 * 9;
-}

From 2574407afb9dc40122d0d55a6c668adb92a07fbb Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 22 Jun 2021 19:33:02 -0400
Subject: [PATCH 062/117] Relocates `MinIntTypeValue` to Numeric.

---
 InstructionSets/CachingExecutor.hpp    | 2 +-
 InstructionSets/Disassembler.hpp       | 2 +-
 {InstructionSets => Numeric}/Sizes.hpp | 0
 3 files changed, 2 insertions(+), 2 deletions(-)
 rename {InstructionSets => Numeric}/Sizes.hpp (100%)

diff --git a/InstructionSets/CachingExecutor.hpp b/InstructionSets/CachingExecutor.hpp
index 198fc2a7b..bc3204e2b 100644
--- a/InstructionSets/CachingExecutor.hpp
+++ b/InstructionSets/CachingExecutor.hpp
@@ -9,7 +9,7 @@
 #ifndef CachingExecutor_hpp
 #define CachingExecutor_hpp
 
-#include "Sizes.hpp"
+#include "../Numeric/Sizes.hpp"
 
 #include <array>
 #include <cstdint>
diff --git a/InstructionSets/Disassembler.hpp b/InstructionSets/Disassembler.hpp
index f590b3000..71f88d59e 100644
--- a/InstructionSets/Disassembler.hpp
+++ b/InstructionSets/Disassembler.hpp
@@ -9,7 +9,7 @@
 #ifndef Disassembler_hpp
 #define Disassembler_hpp
 
-#include "Sizes.hpp"
+#include "../Numeric/Sizes.hpp"
 
 #include <list>
 #include <map>
diff --git a/InstructionSets/Sizes.hpp b/Numeric/Sizes.hpp
similarity index 100%
rename from InstructionSets/Sizes.hpp
rename to Numeric/Sizes.hpp

From d2ab0dd839422410e3a17b12ad309b10f9310f96 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 22 Jun 2021 19:33:29 -0400
Subject: [PATCH 063/117] Adds a quick way to get the compiler to pick an
 integral type.

---
 Numeric/LFSR.hpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Numeric/LFSR.hpp b/Numeric/LFSR.hpp
index 3bf8a8881..ccde6a35b 100644
--- a/Numeric/LFSR.hpp
+++ b/Numeric/LFSR.hpp
@@ -12,6 +12,8 @@
 #include <cstdint>
 #include <cstdlib>
 
+#include "Sizes.hpp"
+
 namespace Numeric {
 
 template <typename IntType> struct LSFRPolynomial {};
@@ -76,6 +78,8 @@ template <typename IntType = uint64_t, IntType polynomial = LSFRPolynomial<IntTy
 		IntType value_ = 0;
 };
 
+template <uint64_t polynomial> class LFSRv: public LFSR<MinIntTypeValue<polynomial>, polynomial> {};
+
 }
 
 #endif /* LFSR_h */

From a66734883a369318cfac95ef00aa81a78dd505dc Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 22 Jun 2021 19:33:41 -0400
Subject: [PATCH 064/117] Starts sketching out Dave.

---
 Machines/Enterprise/Dave.cpp                  | 14 +++++++
 Machines/Enterprise/Dave.hpp                  | 40 +++++++++++++++++++
 Machines/Enterprise/Enterprise.cpp            | 11 ++++-
 .../Clock Signal.xcodeproj/project.pbxproj    | 18 +++++++--
 4 files changed, 77 insertions(+), 6 deletions(-)
 create mode 100644 Machines/Enterprise/Dave.cpp
 create mode 100644 Machines/Enterprise/Dave.hpp

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
new file mode 100644
index 000000000..970d9abcb
--- /dev/null
+++ b/Machines/Enterprise/Dave.cpp
@@ -0,0 +1,14 @@
+//
+//  Dave.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 22/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#include "Dave.hpp"
+
+using namespace Enterprise;
+
+void Dave::write(uint16_t address, uint8_t value) {
+}
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
new file mode 100644
index 000000000..758ce863e
--- /dev/null
+++ b/Machines/Enterprise/Dave.hpp
@@ -0,0 +1,40 @@
+//
+//  Dave.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 22/06/2021.
+//  Copyright © 2021 Thomas Harte. All rights reserved.
+//
+
+#ifndef Dave_hpp
+#define Dave_hpp
+
+#include <cstdint>
+
+#include "../../Numeric/LFSR.hpp"
+
+namespace Enterprise {
+
+/*!
+	Models a subset of Dave's behaviour; memory mapping and interrupt status
+	is integrated into the main Enterprise machine.
+*/
+class Dave {
+	public:
+		void write(uint16_t address, uint8_t value);
+
+	private:
+
+		// Various polynomials that contribute to audio generation.
+		Numeric::LFSRv<0xc> poly4_;
+		Numeric::LFSRv<0x14> poly5_;
+		Numeric::LFSRv<0x60> poly7_;
+		Numeric::LFSRv<0x110> poly9_;
+		Numeric::LFSRv<0x500> poly11_;
+		Numeric::LFSRv<0x6000> poly15_;
+		Numeric::LFSRv<0x12000> poly17_;
+};
+
+}
+
+#endif /* Dave_hpp */
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 1ba476c84..d1bae8b27 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -8,9 +8,10 @@
 
 #include "Enterprise.hpp"
 
+#include "Dave.hpp"
+#include "EXDos.hpp"
 #include "Keyboard.hpp"
 #include "Nick.hpp"
-#include "EXDos.hpp"
 
 #include "../MachineTypes.hpp"
 
@@ -253,6 +254,10 @@ template <bool has_disk_controller> class ConcreteMachine:
 								*cycle.value = 0xff;
 							}
 						break;
+						case 0xb6:
+							// TODO: joystick input.
+							*cycle.value = 0xff;
+						break;
 					}
 				break;
 
@@ -288,7 +293,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 						case 0xa4:	case 0xa5:	case 0xa6:	case 0xa7:
 						case 0xa8:	case 0xa9:	case 0xaa:	case 0xab:
 						case 0xac:	case 0xad:	case 0xae:	case 0xaf:
-//							printf("TODO: audio adjust %04x <- %02x\n", address, *cycle.value);
+							dave_.write(address, *cycle.value);
 						break;
 
 						case 0xb4:
@@ -446,6 +451,8 @@ template <bool has_disk_controller> class ConcreteMachine:
 		bool previous_nick_interrupt_line_ = false;
 		// Cf. timing guesses above.
 
+		Dave dave_;
+
 		// MARK: - EXDos card.
 		EXDos exdos_;
 };
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index ff6cbeb57..8587d4e08 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -998,6 +998,8 @@
 		4BFCA1291ECBE7A700AC40C1 /* zexall.com in Resources */ = {isa = PBXBuildFile; fileRef = 4BFCA1281ECBE7A700AC40C1 /* zexall.com */; };
 		4BFCA12B1ECBE7C400AC40C1 /* ZexallTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BFCA12A1ECBE7C400AC40C1 /* ZexallTests.swift */; };
 		4BFDD78C1F7F2DB4008579B9 /* ImplicitSectors.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BFDD78B1F7F2DB4008579B9 /* ImplicitSectors.cpp */; };
+		4BFEA2EF2682A7B900EBF94C /* Dave.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BFEA2ED2682A7B900EBF94C /* Dave.cpp */; };
+		4BFEA2F02682A7B900EBF94C /* Dave.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BFEA2ED2682A7B900EBF94C /* Dave.cpp */; };
 		4BFF1D3922337B0300838EA1 /* 68000Storage.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BFF1D3822337B0300838EA1 /* 68000Storage.cpp */; };
 		4BFF1D3A22337B0300838EA1 /* 68000Storage.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BFF1D3822337B0300838EA1 /* 68000Storage.cpp */; };
 		4BFF1D3D2235C3C100838EA1 /* EmuTOSTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4BFF1D3C2235C3C100838EA1 /* EmuTOSTests.mm */; };
@@ -2072,6 +2074,9 @@
 		4BFDD78A1F7F2DB4008579B9 /* ImplicitSectors.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = ImplicitSectors.hpp; sourceTree = "<group>"; };
 		4BFDD78B1F7F2DB4008579B9 /* ImplicitSectors.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = ImplicitSectors.cpp; sourceTree = "<group>"; };
 		4BFE7B861FC39BF100160B38 /* StandardOptions.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = StandardOptions.hpp; sourceTree = "<group>"; };
+		4BFEA2ED2682A7B900EBF94C /* Dave.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = Dave.cpp; sourceTree = "<group>"; };
+		4BFEA2EE2682A7B900EBF94C /* Dave.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Dave.hpp; sourceTree = "<group>"; };
+		4BFEA2F12682A90200EBF94C /* Sizes.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = Sizes.hpp; sourceTree = "<group>"; };
 		4BFF1D342233778C00838EA1 /* 68000.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = 68000.hpp; sourceTree = "<group>"; };
 		4BFF1D37223379D500838EA1 /* 68000Storage.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = 68000Storage.hpp; sourceTree = "<group>"; };
 		4BFF1D3822337B0300838EA1 /* 68000Storage.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = 68000Storage.cpp; sourceTree = "<group>"; };
@@ -2116,10 +2121,12 @@
 		4B051C9F2676F52200CA44E8 /* Enterprise */ = {
 			isa = PBXGroup;
 			children = (
+				4BFEA2ED2682A7B900EBF94C /* Dave.cpp */,
 				4B051CA12676F52200CA44E8 /* Enterprise.cpp */,
 				4B051CB42680158600CA44E8 /* EXDos.cpp */,
 				4B051CAE267C1CA200CA44E8 /* Keyboard.cpp */,
 				4B051CAA26783E2000CA44E8 /* Nick.cpp */,
+				4BFEA2EE2682A7B900EBF94C /* Dave.hpp */,
 				4B051CA02676F52200CA44E8 /* Enterprise.hpp */,
 				4B051CB52680158600CA44E8 /* EXDos.hpp */,
 				4B051CAF267C1CA200CA44E8 /* Keyboard.hpp */,
@@ -2703,34 +2710,36 @@
 		4B45188C1F75FD1B00926311 /* Formats */ = {
 			isa = PBXGroup;
 			children = (
+				4B80CD74256CA15E00176FCC /* 2MG.cpp */,
 				4B45188D1F75FD1B00926311 /* AcornADF.cpp */,
 				4B0333AD2094081A0050B93D /* AppleDSK.cpp */,
 				4B45188F1F75FD1B00926311 /* CPCDSK.cpp */,
 				4B4518911F75FD1B00926311 /* D64.cpp */,
 				4BAF2B4C2004580C00480230 /* DMK.cpp */,
+				4BEBFB4B2002C4BF000708CC /* FAT12.cpp */,
 				4B4518931F75FD1B00926311 /* G64.cpp */,
 				4B4518951F75FD1B00926311 /* HFE.cpp */,
 				4BB4BFAE22A42F290069048D /* MacintoshIMG.cpp */,
 				4B58601C1F806AB200AEE2E3 /* MFMSectorDump.cpp */,
 				4BC131782346DF2B00E4FF3D /* MSA.cpp */,
-				4BEBFB4B2002C4BF000708CC /* FAT12.cpp */,
 				4B0F94FC208C1A1600FE41D9 /* NIB.cpp */,
 				4B4518971F75FD1B00926311 /* OricMFMDSK.cpp */,
 				4B4518991F75FD1B00926311 /* SSD.cpp */,
 				4BE0A3EC237BB170002AB46F /* ST.cpp */,
 				4B7BA03323C58B1E00B98D9E /* STX.cpp */,
 				4B6ED2EE208E2F8A0047B343 /* WOZ.cpp */,
+				4B80CD75256CA15E00176FCC /* 2MG.hpp */,
 				4B45188E1F75FD1B00926311 /* AcornADF.hpp */,
 				4B0333AE2094081A0050B93D /* AppleDSK.hpp */,
 				4B4518901F75FD1B00926311 /* CPCDSK.hpp */,
 				4B4518921F75FD1B00926311 /* D64.hpp */,
 				4BAF2B4D2004580C00480230 /* DMK.hpp */,
+				4BEBFB4C2002C4BF000708CC /* FAT12.hpp */,
 				4B4518941F75FD1B00926311 /* G64.hpp */,
 				4B4518961F75FD1B00926311 /* HFE.hpp */,
 				4BB4BFAF22A42F290069048D /* MacintoshIMG.hpp */,
 				4B58601D1F806AB200AEE2E3 /* MFMSectorDump.hpp */,
 				4BC131792346DF2B00E4FF3D /* MSA.hpp */,
-				4BEBFB4C2002C4BF000708CC /* FAT12.hpp */,
 				4B0F94FD208C1A1600FE41D9 /* NIB.hpp */,
 				4B4518981F75FD1B00926311 /* OricMFMDSK.hpp */,
 				4B45189A1F75FD1B00926311 /* SSD.hpp */,
@@ -2738,8 +2747,6 @@
 				4B7BA03223C58B1E00B98D9E /* STX.hpp */,
 				4B6ED2EF208E2F8A0047B343 /* WOZ.hpp */,
 				4BFDD7891F7F2DB4008579B9 /* Utility */,
-				4B80CD74256CA15E00176FCC /* 2MG.cpp */,
-				4B80CD75256CA15E00176FCC /* 2MG.hpp */,
 			);
 			path = Formats;
 			sourceTree = "<group>";
@@ -3096,6 +3103,7 @@
 			children = (
 				4B7BA03E23D55E7900B98D9E /* CRC.hpp */,
 				4B7BA03F23D55E7900B98D9E /* LFSR.hpp */,
+				4BFEA2F12682A90200EBF94C /* Sizes.hpp */,
 			);
 			name = Numeric;
 			path = ../../Numeric;
@@ -5267,6 +5275,7 @@
 				4BB307BC235001C300457D33 /* 6850.cpp in Sources */,
 				4B055AB31FAE860F0060FFFF /* CSW.cpp in Sources */,
 				4B89451D201967B4007DE474 /* Disk.cpp in Sources */,
+				4BFEA2F02682A7B900EBF94C /* Dave.cpp in Sources */,
 				4BDACBED22FFA5D20045EF7E /* ncr5380.cpp in Sources */,
 				4BC131772346DE9100E4FF3D /* StaticAnalyser.cpp in Sources */,
 				4B055ACF1FAE9B030060FFFF /* SoundGenerator.cpp in Sources */,
@@ -5517,6 +5526,7 @@
 				4B7BA03023C2B19C00B98D9E /* Jasmin.cpp in Sources */,
 				4B7136911F789C93008B8ED9 /* SegmentParser.cpp in Sources */,
 				4BEDA3BA25B25563000C2DBD /* Decoder.cpp in Sources */,
+				4BFEA2EF2682A7B900EBF94C /* Dave.cpp in Sources */,
 				4B4518A21F75FD1C00926311 /* G64.cpp in Sources */,
 				4B89452C201967B4007DE474 /* Tape.cpp in Sources */,
 				4B448E811F1C45A00009ABD6 /* TZX.cpp in Sources */,

From 8319aca3511444114bfa89a87171ffd77ab5420c Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 22 Jun 2021 20:50:03 -0400
Subject: [PATCH 065/117] Correct syntax errors.

---
 Machines/Enterprise/Dave.cpp | 2 ++
 Numeric/LFSR.hpp             | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 970d9abcb..b9e3301e1 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -11,4 +11,6 @@
 using namespace Enterprise;
 
 void Dave::write(uint16_t address, uint8_t value) {
+	(void)address;
+	(void)value;
 }
diff --git a/Numeric/LFSR.hpp b/Numeric/LFSR.hpp
index ccde6a35b..04f4cc2fc 100644
--- a/Numeric/LFSR.hpp
+++ b/Numeric/LFSR.hpp
@@ -78,7 +78,7 @@ template <typename IntType = uint64_t, IntType polynomial = LSFRPolynomial<IntTy
 		IntType value_ = 0;
 };
 
-template <uint64_t polynomial> class LFSRv: public LFSR<MinIntTypeValue<polynomial>, polynomial> {};
+template <uint64_t polynomial> class LFSRv: public LFSR<typename MinIntTypeValue<polynomial>::type, polynomial> {};
 
 }
 

From 0afa14337565499755ed64deefe373cfbbd90e92 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 22 Jun 2021 21:31:46 -0400
Subject: [PATCH 066/117] Add missing include.

---
 Numeric/Sizes.hpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Numeric/Sizes.hpp b/Numeric/Sizes.hpp
index 9d3ed9522..d9a56a40a 100644
--- a/Numeric/Sizes.hpp
+++ b/Numeric/Sizes.hpp
@@ -10,6 +10,7 @@
 #define Sizes_h
 
 #include <limits>
+#include <type_traits>
 
 /*!
 	Maps to the smallest integral type that can contain max_value, from the following options:

From 88f0f2b62361c9b8218d83fb391a47ce2a2ba8ff Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 22 Jun 2021 21:39:07 -0400
Subject: [PATCH 067/117] Adds to the macOS UI and wires through all Enterprise
 options.

---
 Analyser/Static/Enterprise/Target.hpp         |   4 +
 .../Machine/StaticAnalyser/CSStaticAnalyser.h |  21 +-
 .../StaticAnalyser/CSStaticAnalyser.mm        |  33 ++-
 .../Base.lproj/MachinePicker.xib              | 265 ++++++++++++------
 .../MachinePicker/MachinePicker.swift         |  65 ++++-
 5 files changed, 298 insertions(+), 90 deletions(-)

diff --git a/Analyser/Static/Enterprise/Target.hpp b/Analyser/Static/Enterprise/Target.hpp
index 2a0fe11d4..1785405c4 100644
--- a/Analyser/Static/Enterprise/Target.hpp
+++ b/Analyser/Static/Enterprise/Target.hpp
@@ -18,20 +18,24 @@ namespace Static {
 namespace Enterprise {
 
 struct Target: public Analyser::Static::Target, public Reflection::StructImpl<Target> {
+	ReflectableEnum(Model, Enterprise64, Enterprise128, Enterprise256);
 	ReflectableEnum(EXOSVersion, v10, v20, v21, v23, Any);
 	ReflectableEnum(BASICVersion, v10, v11, v21, Any, None);
 	ReflectableEnum(DOS, EPDOS, EXDOS, None);
 
+	Model model = Model::Enterprise128;
 	EXOSVersion exos_version = EXOSVersion::Any;
 	BASICVersion basic_version = BASICVersion::None;
 	DOS dos = DOS::None;
 
 	Target() : Analyser::Static::Target(Machine::Enterprise) {
 		if(needs_declare()) {
+			AnnounceEnum(Model);
 			AnnounceEnum(EXOSVersion);
 			AnnounceEnum(BASICVersion);
 			AnnounceEnum(DOS);
 
+			DeclareField(model);
 			DeclareField(exos_version);
 			DeclareField(basic_version);
 			DeclareField(dos);
diff --git a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h
index d064f48e8..11d6e9841 100644
--- a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h	
+++ b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h	
@@ -47,6 +47,25 @@ typedef NS_ENUM(NSInteger, CSMachineEnterpriseModel) {
 	CSMachineEnterpriseModel256,
 };
 
+typedef NS_ENUM(NSInteger, CSMachineEnterpriseEXOS) {
+	CSMachineEnterpriseEXOSVersion21,
+	CSMachineEnterpriseEXOSVersion20,
+	CSMachineEnterpriseEXOSVersion10,
+};
+
+typedef NS_ENUM(NSInteger, CSMachineEnterpriseBASIC) {
+	CSMachineEnterpriseBASICVersion21,
+	CSMachineEnterpriseBASICVersion11,
+	CSMachineEnterpriseBASICVersion10,
+	CSMachineEnterpriseBASICNone,
+};
+
+typedef NS_ENUM(NSInteger, CSMachineEnterpriseDOS) {
+	CSMachineEnterpriseDOSEXDOS,
+	CSMachineEnterpriseDOSEPDOS,
+	CSMachineEnterpriseDOSNone,
+};
+
 typedef NS_ENUM(NSInteger, CSMachineMacintoshModel) {
 	CSMachineMacintoshModel128k,
 	CSMachineMacintoshModel512k,
@@ -102,7 +121,7 @@ typedef int Kilobytes;
 - (instancetype)initWithAppleIIgsModel:(CSMachineAppleIIgsModel)model memorySize:(Kilobytes)memorySize;
 - (instancetype)initWithAtariSTModel:(CSMachineAtariSTModel)model;
 - (instancetype)initWithElectronDFS:(BOOL)dfs adfs:(BOOL)adfs ap6:(BOOL)ap6 sidewaysRAM:(BOOL)sidewaysRAM;
-- (instancetype)initWithEnterpriseModel:(CSMachineEnterpriseModel)model;
+- (instancetype)initWithEnterpriseModel:(CSMachineEnterpriseModel)model exosVersion:(CSMachineEnterpriseEXOS)exosVersion basicVersion:(CSMachineEnterpriseBASIC)basicVersion dos:(CSMachineEnterpriseDOS)dos;
 - (instancetype)initWithMacintoshModel:(CSMachineMacintoshModel)model;
 - (instancetype)initWithMSXRegion:(CSMachineMSXRegion)region hasDiskDrive:(BOOL)hasDiskDrive;
 - (instancetype)initWithOricModel:(CSMachineOricModel)model diskInterface:(CSMachineOricDiskInterface)diskInterface;
diff --git a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm
index 5a7a4032c..787f33d6c 100644
--- a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm	
+++ b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm	
@@ -131,12 +131,41 @@
 	return self;
 }
 
-- (instancetype)initWithEnterpriseModel:(CSMachineEnterpriseModel)model {
+- (instancetype)initWithEnterpriseModel:(CSMachineEnterpriseModel)model exosVersion:(CSMachineEnterpriseEXOS)exosVersion basicVersion:(CSMachineEnterpriseBASIC)basicVersion dos:(CSMachineEnterpriseDOS)dos {
 	self = [super init];
 	if(self) {
 		using Target = Analyser::Static::Enterprise::Target;
 		auto target = std::make_unique<Target>();
-		// TODO: apply model.
+
+		switch(model) {
+			case CSMachineEnterpriseModel64:		target->model = Target::Model::Enterprise64;		break;
+			default:
+			case CSMachineEnterpriseModel128:		target->model = Target::Model::Enterprise128;		break;
+			case CSMachineEnterpriseModel256:		target->model = Target::Model::Enterprise256;		break;
+		}
+
+		switch(exosVersion) {
+			case CSMachineEnterpriseEXOSVersion21:	target->exos_version = Target::EXOSVersion::v21;	break;
+			default:
+			case CSMachineEnterpriseEXOSVersion20:	target->exos_version = Target::EXOSVersion::v20;	break;
+			case CSMachineEnterpriseEXOSVersion10:	target->exos_version = Target::EXOSVersion::v10;	break;
+		}
+
+		switch(basicVersion) {
+			case CSMachineEnterpriseBASICNone:		target->basic_version = Target::BASICVersion::None;	break;
+			default:
+			case CSMachineEnterpriseBASICVersion21:	target->basic_version = Target::BASICVersion::v21;	break;
+			case CSMachineEnterpriseBASICVersion11:	target->basic_version = Target::BASICVersion::v11;	break;
+			case CSMachineEnterpriseBASICVersion10:	target->basic_version = Target::BASICVersion::v10;	break;
+		}
+
+		switch(dos) {
+			case CSMachineEnterpriseDOSEXDOS:		target->dos = Target::DOS::EXDOS;					break;
+			case CSMachineEnterpriseDOSEPDOS:		target->dos = Target::DOS::EPDOS;					break;
+			default:
+			case CSMachineEnterpriseDOSNone:		target->dos = Target::DOS::None;					break;
+		}
+
 		_targets.push_back(std::move(target));
 	}
 	return self;
diff --git a/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib b/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib
index 75127f3c4..4b162af57 100644
--- a/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib	
+++ b/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib	
@@ -64,11 +64,11 @@ Gw
                         <tabViewItems>
                             <tabViewItem label="Apple II" identifier="appleii" id="P59-QG-LOa">
                                 <view key="view" id="dHz-Yv-GNq">
-                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="V5Z-dX-Ns4">
-                                            <rect key="frame" x="18" y="163" width="46" height="16"/>
+                                            <rect key="frame" x="18" y="185" width="46" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Model:" id="qV3-2P-3JW">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -76,7 +76,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="WnO-ef-IC6">
-                                            <rect key="frame" x="18" y="133" width="96" height="16"/>
+                                            <rect key="frame" x="18" y="155" width="96" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Disk controller:" id="kbf-rc-Y4M">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -84,7 +84,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="jli-ac-Sij">
-                                            <rect key="frame" x="67" y="157" width="117" height="25"/>
+                                            <rect key="frame" x="67" y="179" width="117" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Apple II" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="VBQ-JG-AeM" id="U6V-us-O2F">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -99,7 +99,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="LSB-WP-FMi">
-                                            <rect key="frame" x="117" y="127" width="134" height="25"/>
+                                            <rect key="frame" x="117" y="149" width="134" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Sixteen Sector" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="16" imageScaling="axesIndependently" inset="2" selectedItem="QaV-Yr-k9o" id="8BT-RV-2Nm">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -115,11 +115,11 @@ Gw
                                     </subviews>
                                     <constraints>
                                         <constraint firstItem="WnO-ef-IC6" firstAttribute="leading" secondItem="dHz-Yv-GNq" secondAttribute="leading" constant="20" symbolic="YES" id="5RF-1w-9HW"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="LSB-WP-FMi" secondAttribute="bottom" constant="5" id="865-cv-qVk"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="LSB-WP-FMi" secondAttribute="bottom" constant="20" symbolic="YES" id="865-cv-qVk"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="LSB-WP-FMi" secondAttribute="trailing" constant="20" symbolic="YES" id="9GL-al-1qi"/>
                                         <constraint firstItem="WnO-ef-IC6" firstAttribute="centerY" secondItem="LSB-WP-FMi" secondAttribute="centerY" id="Fuj-zT-MIm"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="jli-ac-Sij" secondAttribute="trailing" constant="20" symbolic="YES" id="I8d-OR-ICN"/>
-                                        <constraint firstItem="jli-ac-Sij" firstAttribute="top" secondItem="dHz-Yv-GNq" secondAttribute="top" constant="5" id="Qi1-CV-A0c"/>
+                                        <constraint firstItem="jli-ac-Sij" firstAttribute="top" secondItem="dHz-Yv-GNq" secondAttribute="top" constant="20" symbolic="YES" id="Qi1-CV-A0c"/>
                                         <constraint firstItem="V5Z-dX-Ns4" firstAttribute="leading" secondItem="dHz-Yv-GNq" secondAttribute="leading" constant="20" symbolic="YES" id="SWc-iX-1We"/>
                                         <constraint firstItem="LSB-WP-FMi" firstAttribute="leading" secondItem="WnO-ef-IC6" secondAttribute="trailing" constant="8" symbolic="YES" id="bte-XA-xNQ"/>
                                         <constraint firstItem="LSB-WP-FMi" firstAttribute="top" secondItem="jli-ac-Sij" secondAttribute="bottom" constant="10" symbolic="YES" id="ki5-JR-vRe"/>
@@ -129,12 +129,12 @@ Gw
                                 </view>
                             </tabViewItem>
                             <tabViewItem label="Apple IIgs" identifier="appleiigs" id="u5E-8n-ghF">
-                                <view key="view" ambiguous="YES" id="jOM-9f-vkk">
-                                    <rect key="frame" x="10" y="7" width="400" height="76"/>
+                                <view key="view" id="jOM-9f-vkk">
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="0d9-IG-gKU">
-                                            <rect key="frame" x="18" y="53" width="46" height="16"/>
+                                            <rect key="frame" x="18" y="185" width="46" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Model:" id="kiv-1P-FWc">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -142,7 +142,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="LES-76-Ovz">
-                                            <rect key="frame" x="18" y="23" width="85" height="16"/>
+                                            <rect key="frame" x="18" y="155" width="85" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Memory size:" id="OLJ-nC-yyj">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -150,7 +150,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="gcS-uy-mzl">
-                                            <rect key="frame" x="67" y="47" width="89" height="25"/>
+                                            <rect key="frame" x="67" y="179" width="89" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="ROM 03" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="2" imageScaling="axesIndependently" inset="2" selectedItem="0TS-DO-O9h" id="hjw-g8-e2f">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -164,7 +164,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="nQa-YS-utT">
-                                            <rect key="frame" x="106" y="17" width="82" height="25"/>
+                                            <rect key="frame" x="106" y="149" width="82" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="8 mb" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="8192" imageScaling="axesIndependently" inset="2" selectedItem="UHg-gU-Xnn" id="dl3-cq-uWO">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -182,24 +182,24 @@ Gw
                                         <constraint firstItem="LES-76-Ovz" firstAttribute="leading" secondItem="jOM-9f-vkk" secondAttribute="leading" constant="20" symbolic="YES" id="2D3-Ve-6CN"/>
                                         <constraint firstItem="0d9-IG-gKU" firstAttribute="leading" secondItem="jOM-9f-vkk" secondAttribute="leading" constant="20" symbolic="YES" id="8Xz-86-tDf"/>
                                         <constraint firstItem="0d9-IG-gKU" firstAttribute="centerY" secondItem="gcS-uy-mzl" secondAttribute="centerY" id="Eww-Qq-eBT"/>
-                                        <constraint firstItem="gcS-uy-mzl" firstAttribute="top" secondItem="jOM-9f-vkk" secondAttribute="top" constant="5" id="F6i-cP-7AR"/>
+                                        <constraint firstItem="gcS-uy-mzl" firstAttribute="top" secondItem="jOM-9f-vkk" secondAttribute="top" constant="20" symbolic="YES" id="F6i-cP-7AR"/>
                                         <constraint firstItem="gcS-uy-mzl" firstAttribute="leading" secondItem="0d9-IG-gKU" secondAttribute="trailing" constant="8" symbolic="YES" id="LUm-rI-LYP"/>
                                         <constraint firstItem="LES-76-Ovz" firstAttribute="centerY" secondItem="nQa-YS-utT" secondAttribute="centerY" id="UdP-U6-OFE"/>
                                         <constraint firstItem="nQa-YS-utT" firstAttribute="leading" secondItem="LES-76-Ovz" secondAttribute="trailing" constant="8" symbolic="YES" id="Xm1-iG-Dgj"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="gcS-uy-mzl" secondAttribute="trailing" constant="20" symbolic="YES" id="a38-Cx-CEh"/>
                                         <constraint firstItem="nQa-YS-utT" firstAttribute="top" secondItem="gcS-uy-mzl" secondAttribute="bottom" constant="10" symbolic="YES" id="aM9-m8-s7z"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="nQa-YS-utT" secondAttribute="trailing" constant="20" symbolic="YES" id="cqx-Jc-rUb"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="nQa-YS-utT" secondAttribute="bottom" constant="5" id="sbT-If-NTU"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="nQa-YS-utT" secondAttribute="bottom" constant="20" symbolic="YES" id="sbT-If-NTU"/>
                                     </constraints>
                                 </view>
                             </tabViewItem>
                             <tabViewItem label="Amstrad CPC" identifier="cpc" id="JmB-OF-xcM">
                                 <view key="view" id="5zS-Nj-Ynx">
-                                    <rect key="frame" x="10" y="7" width="400" height="76"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="00d-sg-Krh">
-                                            <rect key="frame" x="67" y="47" width="96" height="25"/>
+                                            <rect key="frame" x="67" y="179" width="96" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="CPC6128" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="6128" imageScaling="axesIndependently" inset="2" selectedItem="klh-ZE-Agp" id="hVJ-h6-iea">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -213,7 +213,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="q9q-sl-J0q">
-                                            <rect key="frame" x="18" y="53" width="46" height="16"/>
+                                            <rect key="frame" x="18" y="185" width="46" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Model:" id="Cw3-q5-1bC">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -224,8 +224,8 @@ Gw
                                     <constraints>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="00d-sg-Krh" secondAttribute="trailing" constant="20" symbolic="YES" id="4AF-5C-2IF"/>
                                         <constraint firstItem="q9q-sl-J0q" firstAttribute="leading" secondItem="5zS-Nj-Ynx" secondAttribute="leading" constant="20" symbolic="YES" id="Wof-5h-gfD"/>
-                                        <constraint firstItem="00d-sg-Krh" firstAttribute="top" secondItem="5zS-Nj-Ynx" secondAttribute="top" constant="5" id="c92-uU-NRr"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="00d-sg-Krh" secondAttribute="bottom" constant="5" id="enU-LN-Nep"/>
+                                        <constraint firstItem="00d-sg-Krh" firstAttribute="top" secondItem="5zS-Nj-Ynx" secondAttribute="top" constant="20" symbolic="YES" id="c92-uU-NRr"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="00d-sg-Krh" secondAttribute="bottom" constant="20" symbolic="YES" id="enU-LN-Nep"/>
                                         <constraint firstItem="00d-sg-Krh" firstAttribute="leading" secondItem="q9q-sl-J0q" secondAttribute="trailing" constant="8" symbolic="YES" id="mA8-US-ndo"/>
                                         <constraint firstItem="q9q-sl-J0q" firstAttribute="centerY" secondItem="00d-sg-Krh" secondAttribute="centerY" id="vA8-IA-Uwf"/>
                                     </constraints>
@@ -233,11 +233,11 @@ Gw
                             </tabViewItem>
                             <tabViewItem label="Atari ST" identifier="atarist" id="a6Y-mx-yFn">
                                 <view key="view" id="nnv-Wi-7hc">
-                                    <rect key="frame" x="10" y="7" width="400" height="76"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="nLf-LI-nWO">
-                                            <rect key="frame" x="18" y="57" width="728" height="16"/>
+                                            <rect key="frame" x="18" y="204" width="364" height="16"/>
                                             <textFieldCell key="cell" lineBreakMode="clipping" title="At present only a 512k Atari ST is supported." id="gBA-ke-mur">
                                                 <font key="font" usesAppearanceFont="YES"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -254,32 +254,32 @@ Gw
                             </tabViewItem>
                             <tabViewItem label="Electron" identifier="electron" id="muc-z9-Vqc">
                                 <view key="view" id="SRc-2D-95G">
-                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="JqM-IK-FMP">
-                                            <rect key="frame" x="18" y="166" width="168" height="18"/>
+                                            <rect key="frame" x="18" y="186" width="168" height="18"/>
                                             <buttonCell key="cell" type="check" title="With Disk Filing System" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="tpW-5C-xKp">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
                                             </buttonCell>
                                         </button>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="945-wU-JOH">
-                                            <rect key="frame" x="18" y="144" width="232" height="18"/>
+                                            <rect key="frame" x="18" y="164" width="232" height="18"/>
                                             <buttonCell key="cell" type="check" title="With Advanced Disk Filing System" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="S0c-Jg-7Pu">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
                                             </buttonCell>
                                         </button>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="cG2-Ph-S3Z">
-                                            <rect key="frame" x="18" y="122" width="231" height="18"/>
+                                            <rect key="frame" x="18" y="142" width="231" height="18"/>
                                             <buttonCell key="cell" type="check" title="With Advanced Plus 6 Utility ROM" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="yjF-XS-zx6">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
                                             </buttonCell>
                                         </button>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="lzo-8g-o4S">
-                                            <rect key="frame" x="18" y="100" width="284" height="18"/>
+                                            <rect key="frame" x="18" y="120" width="284" height="18"/>
                                             <buttonCell key="cell" type="check" title="Fill unused ROM banks with sideways RAM" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="JEz-eK-uWp">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
@@ -289,13 +289,13 @@ Gw
                                     <constraints>
                                         <constraint firstItem="945-wU-JOH" firstAttribute="leading" secondItem="SRc-2D-95G" secondAttribute="leading" constant="20" symbolic="YES" id="1iM-70-oZq"/>
                                         <constraint firstItem="cG2-Ph-S3Z" firstAttribute="top" secondItem="945-wU-JOH" secondAttribute="bottom" constant="6" symbolic="YES" id="E9b-RP-9vj"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="lzo-8g-o4S" secondAttribute="bottom" constant="5" id="FM6-AA-Vhf"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="lzo-8g-o4S" secondAttribute="bottom" constant="20" symbolic="YES" id="FM6-AA-Vhf"/>
                                         <constraint firstItem="JqM-IK-FMP" firstAttribute="leading" secondItem="SRc-2D-95G" secondAttribute="leading" constant="20" symbolic="YES" id="NfY-dE-aJw"/>
                                         <constraint firstItem="lzo-8g-o4S" firstAttribute="top" secondItem="cG2-Ph-S3Z" secondAttribute="bottom" constant="6" symbolic="YES" id="S45-42-Gtv"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="lzo-8g-o4S" secondAttribute="trailing" constant="20" symbolic="YES" id="X3p-qJ-ENH"/>
                                         <constraint firstItem="lzo-8g-o4S" firstAttribute="leading" secondItem="SRc-2D-95G" secondAttribute="leading" constant="20" symbolic="YES" id="b5a-SX-2ty"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="945-wU-JOH" secondAttribute="trailing" constant="20" symbolic="YES" id="dmY-PV-ap4"/>
-                                        <constraint firstItem="JqM-IK-FMP" firstAttribute="top" secondItem="SRc-2D-95G" secondAttribute="top" constant="3" id="ggl-QH-mV4"/>
+                                        <constraint firstItem="JqM-IK-FMP" firstAttribute="top" secondItem="SRc-2D-95G" secondAttribute="top" constant="20" symbolic="YES" id="ggl-QH-mV4"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="cG2-Ph-S3Z" secondAttribute="trailing" constant="20" symbolic="YES" id="m6t-dP-71d"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="JqM-IK-FMP" secondAttribute="trailing" constant="20" symbolic="YES" id="mvO-UZ-BtT"/>
                                         <constraint firstItem="cG2-Ph-S3Z" firstAttribute="leading" secondItem="SRc-2D-95G" secondAttribute="leading" constant="20" symbolic="YES" id="npw-IZ-6xU"/>
@@ -308,28 +308,129 @@ Gw
                                     <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
-                                        <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="Bkl-NN-Hml">
-                                            <rect key="frame" x="18" y="203" width="168" height="18"/>
-                                            <buttonCell key="cell" type="check" title="With Disk Filing System" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="yKr-e9-cKA">
-                                                <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
+                                        <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="PhH-bu-pb5">
+                                            <rect key="frame" x="80" y="179" width="129" height="25"/>
+                                            <popUpButtonCell key="cell" type="push" title="Enterprise 128" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="128" imageScaling="axesIndependently" inset="2" selectedItem="roH-nL-f8o" id="z9O-XC-XBv">
+                                                <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
+                                                <font key="font" metaFont="menu"/>
+                                                <menu key="menu" id="ojI-Vb-iHz">
+                                                    <items>
+                                                        <menuItem title="Enterprise 256" tag="256" id="Al3-A0-tvw"/>
+                                                        <menuItem title="Enterprise 128" state="on" tag="128" id="roH-nL-f8o"/>
+                                                        <menuItem title="Enterprise 64" tag="64" id="vNG-Tv-bDI"/>
+                                                    </items>
+                                                </menu>
+                                            </popUpButtonCell>
+                                        </popUpButton>
+                                        <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="nen-Za-7zH">
+                                            <rect key="frame" x="64" y="149" width="107" height="25"/>
+                                            <popUpButtonCell key="cell" type="push" title="Version 2.1" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="21" imageScaling="axesIndependently" inset="2" selectedItem="Qja-xZ-wVM" id="xGG-ri-8Sb">
+                                                <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
+                                                <font key="font" metaFont="menu"/>
+                                                <menu key="menu" id="uNC-hA-d5z">
+                                                    <items>
+                                                        <menuItem title="Version 2.1" state="on" tag="21" id="Qja-xZ-wVM"/>
+                                                        <menuItem title="Version 2.0" tag="20" id="XTj-l7-KX3"/>
+                                                        <menuItem title="Version 1.0" tag="10" id="Ky2-2D-wcY"/>
+                                                    </items>
+                                                </menu>
+                                            </popUpButtonCell>
+                                        </popUpButton>
+                                        <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="hIr-GH-7xi">
+                                            <rect key="frame" x="67" y="119" width="105" height="25"/>
+                                            <popUpButtonCell key="cell" type="push" title="Version 2.1" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="21" imageScaling="axesIndependently" inset="2" selectedItem="TME-cv-Jh1" id="9mQ-GW-lq9">
+                                                <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
+                                                <font key="font" metaFont="menu"/>
+                                                <menu key="menu" id="VcH-Xm-1hY">
+                                                    <items>
+                                                        <menuItem title="Version 2.1" state="on" tag="21" id="TME-cv-Jh1"/>
+                                                        <menuItem title="Version 1.1" tag="11" id="7P2-aF-6fp"/>
+                                                        <menuItem title="Version 1.0" tag="10" id="j8p-uY-BhG"/>
+                                                        <menuItem title="None" id="eGk-Bj-IVT"/>
+                                                    </items>
+                                                </menu>
+                                            </popUpButtonCell>
+                                        </popUpButton>
+                                        <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="syE-e7-TjU">
+                                            <rect key="frame" x="57" y="89" width="83" height="25"/>
+                                            <popUpButtonCell key="cell" type="push" title="None" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="qoS-KO-iEZ" id="NvO-Zm-2Rq">
+                                                <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
+                                                <font key="font" metaFont="menu"/>
+                                                <menu key="menu" title="DOS" id="sdr-al-7mi">
+                                                    <items>
+                                                        <menuItem title="EXDOS" tag="1" id="8rP-2w-PdU"/>
+                                                        <menuItem title="EPDOS" tag="2" id="Ke7-AJ-8Rx"/>
+                                                        <menuItem title="None" state="on" id="qoS-KO-iEZ"/>
+                                                    </items>
+                                                </menu>
+                                            </popUpButtonCell>
+                                        </popUpButton>
+                                        <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ykc-W1-YaS">
+                                            <rect key="frame" x="18" y="155" width="43" height="16"/>
+                                            <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="EXOS:" id="gUC-PN-zVL">
                                                 <font key="font" metaFont="system"/>
-                                            </buttonCell>
-                                        </button>
+                                                <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
+                                                <color key="backgroundColor" name="controlColor" catalog="System" colorSpace="catalog"/>
+                                            </textFieldCell>
+                                        </textField>
+                                        <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="frx-nk-c3P">
+                                            <rect key="frame" x="18" y="185" width="59" height="16"/>
+                                            <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Machine:" id="uTv-hH-mIC">
+                                                <font key="font" metaFont="system"/>
+                                                <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
+                                                <color key="backgroundColor" name="controlColor" catalog="System" colorSpace="catalog"/>
+                                            </textFieldCell>
+                                        </textField>
+                                        <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="dzd-tH-BjX">
+                                            <rect key="frame" x="18" y="125" width="46" height="16"/>
+                                            <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="BASIC:" id="ai1-oR-X6Y">
+                                                <font key="font" metaFont="system"/>
+                                                <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
+                                                <color key="backgroundColor" name="controlColor" catalog="System" colorSpace="catalog"/>
+                                            </textFieldCell>
+                                        </textField>
+                                        <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="pxr-Bq-yh0">
+                                            <rect key="frame" x="18" y="95" width="36" height="16"/>
+                                            <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="DOS:" id="NFk-cp-DfS">
+                                                <font key="font" metaFont="system"/>
+                                                <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
+                                                <color key="backgroundColor" name="controlColor" catalog="System" colorSpace="catalog"/>
+                                            </textFieldCell>
+                                        </textField>
                                     </subviews>
                                     <constraints>
-                                        <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="Bkl-NN-Hml" secondAttribute="trailing" constant="20" symbolic="YES" id="0JK-jh-Dyl"/>
-                                        <constraint firstItem="Bkl-NN-Hml" firstAttribute="top" secondItem="1cs-PX-RAH" secondAttribute="top" constant="3" id="P2d-9U-kdR"/>
-                                        <constraint firstItem="Bkl-NN-Hml" firstAttribute="leading" secondItem="1cs-PX-RAH" secondAttribute="leading" constant="20" symbolic="YES" id="tjU-md-m2j"/>
+                                        <constraint firstItem="dzd-tH-BjX" firstAttribute="centerY" secondItem="hIr-GH-7xi" secondAttribute="centerY" id="3TV-RU-Kgh"/>
+                                        <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="hIr-GH-7xi" secondAttribute="trailing" constant="20" symbolic="YES" id="44v-9O-y7L"/>
+                                        <constraint firstItem="frx-nk-c3P" firstAttribute="centerY" secondItem="PhH-bu-pb5" secondAttribute="centerY" id="6Wc-aR-wuL"/>
+                                        <constraint firstItem="dzd-tH-BjX" firstAttribute="leading" secondItem="1cs-PX-RAH" secondAttribute="leading" constant="20" symbolic="YES" id="7RZ-Om-TAa"/>
+                                        <constraint firstItem="ykc-W1-YaS" firstAttribute="centerY" secondItem="nen-Za-7zH" secondAttribute="centerY" id="CLa-6E-8BB"/>
+                                        <constraint firstItem="PhH-bu-pb5" firstAttribute="leading" secondItem="frx-nk-c3P" secondAttribute="trailing" constant="8" symbolic="YES" id="ENF-TY-TQ7"/>
+                                        <constraint firstItem="nen-Za-7zH" firstAttribute="leading" secondItem="ykc-W1-YaS" secondAttribute="trailing" constant="8" symbolic="YES" id="GWR-VI-9PG"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="syE-e7-TjU" secondAttribute="bottom" constant="20" symbolic="YES" id="K3s-FA-zMB"/>
+                                        <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="PhH-bu-pb5" secondAttribute="trailing" constant="20" symbolic="YES" id="LwB-ef-uF4"/>
+                                        <constraint firstItem="PhH-bu-pb5" firstAttribute="top" secondItem="1cs-PX-RAH" secondAttribute="top" constant="20" symbolic="YES" id="Myt-i4-jVq"/>
+                                        <constraint firstItem="pxr-Bq-yh0" firstAttribute="leading" secondItem="1cs-PX-RAH" secondAttribute="leading" constant="20" symbolic="YES" id="Qzp-IY-Pa0"/>
+                                        <constraint firstItem="PhH-bu-pb5" firstAttribute="leading" secondItem="frx-nk-c3P" secondAttribute="trailing" constant="8" symbolic="YES" id="T3e-u7-fiQ"/>
+                                        <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="syE-e7-TjU" secondAttribute="trailing" constant="20" symbolic="YES" id="TEX-Nw-y2K"/>
+                                        <constraint firstItem="frx-nk-c3P" firstAttribute="leading" secondItem="1cs-PX-RAH" secondAttribute="leading" constant="20" symbolic="YES" id="TgR-RR-eA1"/>
+                                        <constraint firstItem="pxr-Bq-yh0" firstAttribute="centerY" secondItem="syE-e7-TjU" secondAttribute="centerY" id="UYw-uz-Am0"/>
+                                        <constraint firstItem="hIr-GH-7xi" firstAttribute="top" secondItem="nen-Za-7zH" secondAttribute="bottom" constant="10" symbolic="YES" id="VOc-2v-s3u"/>
+                                        <constraint firstItem="syE-e7-TjU" firstAttribute="top" secondItem="hIr-GH-7xi" secondAttribute="bottom" constant="10" symbolic="YES" id="W9S-on-Heq"/>
+                                        <constraint firstItem="nen-Za-7zH" firstAttribute="top" secondItem="PhH-bu-pb5" secondAttribute="bottom" constant="10" symbolic="YES" id="Yes-o3-V0m"/>
+                                        <constraint firstItem="ykc-W1-YaS" firstAttribute="leading" secondItem="1cs-PX-RAH" secondAttribute="leading" constant="20" symbolic="YES" id="bAP-lx-pdi"/>
+                                        <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="nen-Za-7zH" secondAttribute="trailing" constant="20" symbolic="YES" id="eEI-5Q-TnO"/>
+                                        <constraint firstItem="syE-e7-TjU" firstAttribute="leading" secondItem="pxr-Bq-yh0" secondAttribute="trailing" constant="8" symbolic="YES" id="fmM-Ma-Jyu"/>
+                                        <constraint firstItem="hIr-GH-7xi" firstAttribute="leading" secondItem="dzd-tH-BjX" secondAttribute="trailing" constant="8" symbolic="YES" id="jDQ-TF-Ogf"/>
                                     </constraints>
                                 </view>
                             </tabViewItem>
                             <tabViewItem label="Macintosh" identifier="mac" id="lmR-z3-xSm">
                                 <view key="view" id="7Yf-vi-Q0W">
-                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ZOY-4E-Cfl">
-                                            <rect key="frame" x="18" y="163" width="46" height="16"/>
+                                            <rect key="frame" x="18" y="185" width="46" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Model:" id="h9r-i6-66j">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -337,7 +438,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="xa6-NA-JY5">
-                                            <rect key="frame" x="67" y="157" width="75" height="25"/>
+                                            <rect key="frame" x="67" y="179" width="75" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Plus" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="3" imageScaling="axesIndependently" inset="2" selectedItem="R6T-hg-rOF" id="1Kb-Q2-BGM">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -353,9 +454,9 @@ Gw
                                         </popUpButton>
                                     </subviews>
                                     <constraints>
-                                        <constraint firstItem="xa6-NA-JY5" firstAttribute="top" secondItem="7Yf-vi-Q0W" secondAttribute="top" constant="5" id="3hY-Ca-mnR"/>
+                                        <constraint firstItem="xa6-NA-JY5" firstAttribute="top" secondItem="7Yf-vi-Q0W" secondAttribute="top" constant="20" symbolic="YES" id="3hY-Ca-mnR"/>
                                         <constraint firstItem="ZOY-4E-Cfl" firstAttribute="leading" secondItem="7Yf-vi-Q0W" secondAttribute="leading" constant="20" symbolic="YES" id="5s6-87-VT6"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="xa6-NA-JY5" secondAttribute="bottom" constant="5" id="KYf-GJ-Y7k"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="xa6-NA-JY5" secondAttribute="bottom" constant="20" symbolic="YES" id="KYf-GJ-Y7k"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="xa6-NA-JY5" secondAttribute="trailing" constant="20" symbolic="YES" id="LZ5-xH-fU0"/>
                                         <constraint firstItem="ZOY-4E-Cfl" firstAttribute="centerY" secondItem="xa6-NA-JY5" secondAttribute="centerY" id="Wa5-KX-3Me"/>
                                         <constraint firstItem="xa6-NA-JY5" firstAttribute="leading" secondItem="ZOY-4E-Cfl" secondAttribute="trailing" constant="8" symbolic="YES" id="ktS-sr-F8L"/>
@@ -364,18 +465,18 @@ Gw
                             </tabViewItem>
                             <tabViewItem label="MSX" identifier="msx" id="6SR-DY-zdI">
                                 <view key="view" id="mWD-An-tR7">
-                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="8xT-Pr-8SE">
-                                            <rect key="frame" x="18" y="136" width="128" height="18"/>
+                                            <rect key="frame" x="18" y="158" width="128" height="18"/>
                                             <buttonCell key="cell" type="check" title="Attach disk drive" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="CB3-nA-VTM">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
                                             </buttonCell>
                                         </button>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="LG6-mP-SeG">
-                                            <rect key="frame" x="71" y="157" width="146" height="25"/>
+                                            <rect key="frame" x="71" y="179" width="146" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="European (PAL)" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="xAh-Ch-tby" id="yR4-yv-Lvu">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -389,7 +490,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ZaD-7v-rMS">
-                                            <rect key="frame" x="18" y="163" width="50" height="16"/>
+                                            <rect key="frame" x="18" y="185" width="50" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Region:" id="x4m-eh-Nif">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -400,9 +501,9 @@ Gw
                                     <constraints>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="LG6-mP-SeG" secondAttribute="trailing" constant="20" symbolic="YES" id="0Oc-n7-gaM"/>
                                         <constraint firstItem="8xT-Pr-8SE" firstAttribute="top" secondItem="LG6-mP-SeG" secondAttribute="bottom" constant="8" symbolic="YES" id="LBt-4m-GDc"/>
-                                        <constraint firstItem="LG6-mP-SeG" firstAttribute="top" secondItem="mWD-An-tR7" secondAttribute="top" constant="5" id="bcb-ZZ-VpQ"/>
+                                        <constraint firstItem="LG6-mP-SeG" firstAttribute="top" secondItem="mWD-An-tR7" secondAttribute="top" constant="20" symbolic="YES" id="bcb-ZZ-VpQ"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="8xT-Pr-8SE" secondAttribute="trailing" constant="20" symbolic="YES" id="l8P-UW-8ig"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="8xT-Pr-8SE" secondAttribute="bottom" constant="3" id="mga-YX-Bek"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="8xT-Pr-8SE" secondAttribute="bottom" constant="20" symbolic="YES" id="mga-YX-Bek"/>
                                         <constraint firstItem="8xT-Pr-8SE" firstAttribute="leading" secondItem="mWD-An-tR7" secondAttribute="leading" constant="20" symbolic="YES" id="q8Q-kh-Opj"/>
                                         <constraint firstItem="LG6-mP-SeG" firstAttribute="leading" secondItem="ZaD-7v-rMS" secondAttribute="trailing" constant="8" symbolic="YES" id="svb-nH-GlP"/>
                                         <constraint firstItem="ZaD-7v-rMS" firstAttribute="leading" secondItem="mWD-An-tR7" secondAttribute="leading" constant="20" symbolic="YES" id="zgh-a5-FNF"/>
@@ -412,11 +513,11 @@ Gw
                             </tabViewItem>
                             <tabViewItem label="Oric" identifier="oric" id="NSx-DC-p4M">
                                 <view key="view" id="sOR-e0-8iZ">
-                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="0ct-tf-uRH">
-                                            <rect key="frame" x="18" y="163" width="46" height="16"/>
+                                            <rect key="frame" x="18" y="185" width="46" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Model:" id="Xm1-7x-YVl">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -424,7 +525,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ENP-hI-BVZ">
-                                            <rect key="frame" x="67" y="157" width="107" height="25"/>
+                                            <rect key="frame" x="67" y="179" width="107" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Oric-1" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="jGN-1a-biF" id="Jll-EJ-cMr">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -438,7 +539,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="fYL-p6-wyn">
-                                            <rect key="frame" x="113" y="127" width="130" height="25"/>
+                                            <rect key="frame" x="113" y="149" width="130" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="None" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="XhK-Jh-oTW" id="aYb-m1-H9X">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -454,7 +555,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="okM-ZI-NbF">
-                                            <rect key="frame" x="18" y="133" width="92" height="16"/>
+                                            <rect key="frame" x="18" y="155" width="92" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Disk interface:" id="SFK-hS-tFC">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -463,7 +564,7 @@ Gw
                                         </textField>
                                     </subviews>
                                     <constraints>
-                                        <constraint firstItem="ENP-hI-BVZ" firstAttribute="top" secondItem="sOR-e0-8iZ" secondAttribute="top" constant="5" id="Bgq-8R-8I4"/>
+                                        <constraint firstItem="ENP-hI-BVZ" firstAttribute="top" secondItem="sOR-e0-8iZ" secondAttribute="top" constant="20" symbolic="YES" id="Bgq-8R-8I4"/>
                                         <constraint firstItem="fYL-p6-wyn" firstAttribute="leading" secondItem="okM-ZI-NbF" secondAttribute="trailing" constant="8" symbolic="YES" id="Pra-lC-JPB"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="ENP-hI-BVZ" secondAttribute="trailing" constant="20" symbolic="YES" id="Sr5-QZ-xU3"/>
                                         <constraint firstItem="ENP-hI-BVZ" firstAttribute="leading" secondItem="0ct-tf-uRH" secondAttribute="trailing" constant="8" symbolic="YES" id="Wcg-1P-z6l"/>
@@ -473,17 +574,17 @@ Gw
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="fYL-p6-wyn" secondAttribute="trailing" constant="20" symbolic="YES" id="ewV-Dw-zj2"/>
                                         <constraint firstItem="0ct-tf-uRH" firstAttribute="leading" secondItem="sOR-e0-8iZ" secondAttribute="leading" constant="20" symbolic="YES" id="huH-9L-97Y"/>
                                         <constraint firstItem="fYL-p6-wyn" firstAttribute="top" secondItem="ENP-hI-BVZ" secondAttribute="bottom" constant="10" symbolic="YES" id="l3T-Ve-0Jw"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="fYL-p6-wyn" secondAttribute="bottom" constant="5" id="mN9-AZ-wSn"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="fYL-p6-wyn" secondAttribute="bottom" constant="20" symbolic="YES" id="mN9-AZ-wSn"/>
                                     </constraints>
                                 </view>
                             </tabViewItem>
                             <tabViewItem label="Vic-20" identifier="vic20" id="cyO-PU-hSU">
                                 <view key="view" id="fLI-XB-QCr">
-                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ueK-gq-gaF">
-                                            <rect key="frame" x="71" y="157" width="146" height="25"/>
+                                            <rect key="frame" x="71" y="179" width="146" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="European (PAL)" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="45i-0n-gau" id="yi7-eo-I0q">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -499,7 +600,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="2eV-Us-eEv">
-                                            <rect key="frame" x="108" y="127" width="116" height="25"/>
+                                            <rect key="frame" x="108" y="149" width="116" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Unexpanded" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="fOl-8Q-fsA" id="rH0-7T-pJE">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -513,7 +614,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="MTh-9p-FqC">
-                                            <rect key="frame" x="18" y="163" width="50" height="16"/>
+                                            <rect key="frame" x="18" y="185" width="50" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Region:" id="F3g-Ya-ypU">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -521,7 +622,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="gRS-DK-rIy">
-                                            <rect key="frame" x="18" y="133" width="87" height="16"/>
+                                            <rect key="frame" x="18" y="155" width="87" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Memory Size:" id="a4I-vG-yCp">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -529,7 +630,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="Lrf-gL-6EI">
-                                            <rect key="frame" x="18" y="106" width="177" height="18"/>
+                                            <rect key="frame" x="18" y="128" width="177" height="18"/>
                                             <buttonCell key="cell" type="check" title="Attach C-1540 disk drive" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="tsq-YD-xw8">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
@@ -541,7 +642,7 @@ Gw
                                         <constraint firstItem="MTh-9p-FqC" firstAttribute="centerY" secondItem="ueK-gq-gaF" secondAttribute="centerY" id="8KD-Bm-KRA"/>
                                         <constraint firstItem="ueK-gq-gaF" firstAttribute="leading" secondItem="MTh-9p-FqC" secondAttribute="trailing" constant="8" symbolic="YES" id="9m6-6j-8j2"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="Lrf-gL-6EI" secondAttribute="trailing" constant="20" symbolic="YES" id="M08-mP-Plz"/>
-                                        <constraint firstItem="ueK-gq-gaF" firstAttribute="top" secondItem="fLI-XB-QCr" secondAttribute="top" constant="5" id="XN3-GK-BX9"/>
+                                        <constraint firstItem="ueK-gq-gaF" firstAttribute="top" secondItem="fLI-XB-QCr" secondAttribute="top" constant="20" symbolic="YES" id="XN3-GK-BX9"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="ueK-gq-gaF" secondAttribute="trailing" constant="20" symbolic="YES" id="YZ9-7N-ssA"/>
                                         <constraint firstItem="MTh-9p-FqC" firstAttribute="leading" secondItem="fLI-XB-QCr" secondAttribute="leading" constant="20" symbolic="YES" id="bgZ-k9-IQC"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="2eV-Us-eEv" secondAttribute="trailing" constant="20" symbolic="YES" id="eiB-vH-17d"/>
@@ -549,18 +650,18 @@ Gw
                                         <constraint firstItem="2eV-Us-eEv" firstAttribute="leading" secondItem="gRS-DK-rIy" secondAttribute="trailing" constant="8" symbolic="YES" id="hQ9-uy-KHg"/>
                                         <constraint firstItem="gRS-DK-rIy" firstAttribute="leading" secondItem="fLI-XB-QCr" secondAttribute="leading" constant="20" symbolic="YES" id="iyp-1K-rdC"/>
                                         <constraint firstItem="gRS-DK-rIy" firstAttribute="centerY" secondItem="2eV-Us-eEv" secondAttribute="centerY" id="qWf-Nb-PfJ"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="Lrf-gL-6EI" secondAttribute="bottom" constant="3" id="vNb-Sw-Mxw"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="Lrf-gL-6EI" secondAttribute="bottom" constant="20" symbolic="YES" id="vNb-Sw-Mxw"/>
                                         <constraint firstItem="Lrf-gL-6EI" firstAttribute="top" secondItem="2eV-Us-eEv" secondAttribute="bottom" constant="8" symbolic="YES" id="zBX-Qq-j5f"/>
                                     </constraints>
                                 </view>
                             </tabViewItem>
                             <tabViewItem label="ZX80" identifier="zx80" id="tMH-kF-GUz">
                                 <view key="view" id="8hL-Vn-Hg0">
-                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="I1a-Eu-5UB">
-                                            <rect key="frame" x="108" y="157" width="116" height="25"/>
+                                            <rect key="frame" x="108" y="179" width="116" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Unexpanded" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="4Sa-jR-xOd" id="B8M-do-Yod">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -574,7 +675,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="NCX-4e-lSu">
-                                            <rect key="frame" x="18" y="163" width="87" height="16"/>
+                                            <rect key="frame" x="18" y="185" width="87" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Memory Size:" id="e6x-TE-OC5">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -582,7 +683,7 @@ Gw
                                             </textFieldCell>
                                         </textField>
                                         <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="ReP-bV-Thu">
-                                            <rect key="frame" x="18" y="136" width="118" height="18"/>
+                                            <rect key="frame" x="18" y="158" width="118" height="18"/>
                                             <buttonCell key="cell" type="check" title="Use ZX81 ROM" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="VQH-nv-Pfm">
                                                 <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                                                 <font key="font" metaFont="system"/>
@@ -594,8 +695,8 @@ Gw
                                         <constraint firstItem="NCX-4e-lSu" firstAttribute="centerY" secondItem="I1a-Eu-5UB" secondAttribute="centerY" id="1ve-sc-QwI"/>
                                         <constraint firstItem="I1a-Eu-5UB" firstAttribute="leading" secondItem="NCX-4e-lSu" secondAttribute="trailing" constant="8" symbolic="YES" id="Bu6-60-74x"/>
                                         <constraint firstItem="NCX-4e-lSu" firstAttribute="leading" secondItem="8hL-Vn-Hg0" secondAttribute="leading" constant="20" symbolic="YES" id="W09-iG-ARI"/>
-                                        <constraint firstItem="I1a-Eu-5UB" firstAttribute="top" secondItem="8hL-Vn-Hg0" secondAttribute="top" constant="5" id="fkf-wO-Q8i"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="ReP-bV-Thu" secondAttribute="bottom" constant="3" id="fmT-7E-hUT"/>
+                                        <constraint firstItem="I1a-Eu-5UB" firstAttribute="top" secondItem="8hL-Vn-Hg0" secondAttribute="top" constant="20" symbolic="YES" id="fkf-wO-Q8i"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="ReP-bV-Thu" secondAttribute="bottom" constant="20" symbolic="YES" id="fmT-7E-hUT"/>
                                         <constraint firstItem="ReP-bV-Thu" firstAttribute="top" secondItem="I1a-Eu-5UB" secondAttribute="bottom" constant="8" symbolic="YES" id="hYk-xC-63o"/>
                                         <constraint firstItem="ReP-bV-Thu" firstAttribute="leading" secondItem="8hL-Vn-Hg0" secondAttribute="leading" constant="20" symbolic="YES" id="qen-KS-rWi"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="ReP-bV-Thu" secondAttribute="trailing" constant="20" symbolic="YES" id="r7F-DT-oRc"/>
@@ -604,11 +705,11 @@ Gw
                             </tabViewItem>
                             <tabViewItem label="ZX81" identifier="zx81" id="Wnn-nQ-gZ6">
                                 <view key="view" id="bmd-gL-gzT">
-                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="5aO-UX-HnX">
-                                            <rect key="frame" x="108" y="157" width="116" height="25"/>
+                                            <rect key="frame" x="108" y="179" width="116" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="Unexpanded" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="7QC-Ij-hES" id="d3W-Gl-3Mf">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -622,7 +723,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="8tU-73-XEE">
-                                            <rect key="frame" x="18" y="163" width="87" height="16"/>
+                                            <rect key="frame" x="18" y="185" width="87" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Memory Size:" id="z4b-oR-Yl2">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -633,20 +734,20 @@ Gw
                                     <constraints>
                                         <constraint firstItem="8tU-73-XEE" firstAttribute="centerY" secondItem="5aO-UX-HnX" secondAttribute="centerY" id="1Jm-YL-OKU"/>
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="5aO-UX-HnX" secondAttribute="trailing" constant="20" symbolic="YES" id="ALj-0x-bFb"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="5aO-UX-HnX" secondAttribute="bottom" constant="5" id="LJ2-W9-fOf"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="5aO-UX-HnX" secondAttribute="bottom" constant="20" symbolic="YES" id="LJ2-W9-fOf"/>
                                         <constraint firstItem="8tU-73-XEE" firstAttribute="leading" secondItem="bmd-gL-gzT" secondAttribute="leading" constant="20" symbolic="YES" id="M6Y-jN-LAf"/>
-                                        <constraint firstItem="5aO-UX-HnX" firstAttribute="top" secondItem="bmd-gL-gzT" secondAttribute="top" constant="5" id="PPD-Jz-qCL"/>
+                                        <constraint firstItem="5aO-UX-HnX" firstAttribute="top" secondItem="bmd-gL-gzT" secondAttribute="top" constant="20" symbolic="YES" id="PPD-Jz-qCL"/>
                                         <constraint firstItem="5aO-UX-HnX" firstAttribute="leading" secondItem="8tU-73-XEE" secondAttribute="trailing" constant="8" symbolic="YES" id="j1u-n4-2IK"/>
                                     </constraints>
                                 </view>
                             </tabViewItem>
                             <tabViewItem label="ZX Spectrum" identifier="spectrum" id="HQv-oF-k8b">
                                 <view key="view" id="bMx-F6-JUb">
-                                    <rect key="frame" x="10" y="7" width="400" height="186"/>
+                                    <rect key="frame" x="10" y="7" width="400" height="223"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="gFZ-d4-WFv">
-                                            <rect key="frame" x="67" y="157" width="76" height="25"/>
+                                            <rect key="frame" x="67" y="179" width="76" height="25"/>
                                             <popUpButtonCell key="cell" type="push" title="16kb" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="16" imageScaling="axesIndependently" inset="2" selectedItem="Fo7-NL-Kv5" id="tYs-sA-oek">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
@@ -663,7 +764,7 @@ Gw
                                             </popUpButtonCell>
                                         </popUpButton>
                                         <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="fJ3-ma-Byy">
-                                            <rect key="frame" x="18" y="163" width="46" height="16"/>
+                                            <rect key="frame" x="18" y="185" width="46" height="16"/>
                                             <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" sendsActionOnEndEditing="YES" title="Model:" id="JId-Tp-LrE">
                                                 <font key="font" metaFont="system"/>
                                                 <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -675,9 +776,9 @@ Gw
                                         <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="gFZ-d4-WFv" secondAttribute="trailing" constant="20" symbolic="YES" id="90E-uI-MQg"/>
                                         <constraint firstItem="fJ3-ma-Byy" firstAttribute="leading" secondItem="bMx-F6-JUb" secondAttribute="leading" constant="20" symbolic="YES" id="9kE-iQ-dxd"/>
                                         <constraint firstItem="fJ3-ma-Byy" firstAttribute="centerY" secondItem="gFZ-d4-WFv" secondAttribute="centerY" id="LxG-5E-Q5Y"/>
-                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="gFZ-d4-WFv" secondAttribute="bottom" constant="5" id="d8S-vX-B5e"/>
+                                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="gFZ-d4-WFv" secondAttribute="bottom" constant="20" symbolic="YES" id="d8S-vX-B5e"/>
                                         <constraint firstItem="gFZ-d4-WFv" firstAttribute="leading" secondItem="fJ3-ma-Byy" secondAttribute="trailing" constant="8" symbolic="YES" id="hKS-47-R2y"/>
-                                        <constraint firstItem="gFZ-d4-WFv" firstAttribute="top" secondItem="bMx-F6-JUb" secondAttribute="top" constant="5" id="wsX-Wq-iPt"/>
+                                        <constraint firstItem="gFZ-d4-WFv" firstAttribute="top" secondItem="bMx-F6-JUb" secondAttribute="top" constant="20" symbolic="YES" id="wsX-Wq-iPt"/>
                                     </constraints>
                                 </view>
                             </tabViewItem>
@@ -770,6 +871,10 @@ Gw
                 <outlet property="electronAP6Button" destination="cG2-Ph-S3Z" id="vkq-1J-KBG"/>
                 <outlet property="electronDFSButton" destination="JqM-IK-FMP" id="C80-1k-TdQ"/>
                 <outlet property="electronSidewaysRAMButton" destination="lzo-8g-o4S" id="LtS-wv-tMf"/>
+                <outlet property="enterpriseBASICButton" destination="hIr-GH-7xi" id="fM6-It-9UO"/>
+                <outlet property="enterpriseDOSButton" destination="syE-e7-TjU" id="sCW-Bj-ZTW"/>
+                <outlet property="enterpriseEXOSButton" destination="nen-Za-7zH" id="NwS-ua-FdA"/>
+                <outlet property="enterpriseModelButton" destination="PhH-bu-pb5" id="8wD-sW-aBw"/>
                 <outlet property="machineNameTable" destination="3go-Eb-GOy" id="Ppf-S0-IP1"/>
                 <outlet property="machineSelector" destination="VUb-QG-x7c" id="crR-hB-jGd"/>
                 <outlet property="macintoshModelTypeButton" destination="xa6-NA-JY5" id="2jX-PY-v2z"/>
diff --git a/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift b/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift
index 24ccd2b9a..dbf8c0b2e 100644
--- a/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift	
+++ b/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift	
@@ -27,14 +27,20 @@ class MachinePicker: NSObject, NSTableViewDataSource, NSTableViewDelegate {
 	@IBOutlet var appleIIgsModelButton: NSPopUpButton!
 	@IBOutlet var appleIIgsMemorySizeButton: NSPopUpButton!
 
+	// MARK: - CPC properties
+	@IBOutlet var cpcModelTypeButton: NSPopUpButton!
+
 	// MARK: - Electron properties
 	@IBOutlet var electronDFSButton: NSButton!
 	@IBOutlet var electronADFSButton: NSButton!
 	@IBOutlet var electronAP6Button: NSButton!
 	@IBOutlet var electronSidewaysRAMButton: NSButton!
 
-	// MARK: - CPC properties
-	@IBOutlet var cpcModelTypeButton: NSPopUpButton!
+	// MARK: - Enterprise properties
+	@IBOutlet var enterpriseModelButton: NSPopUpButton!
+	@IBOutlet var enterpriseEXOSButton: NSPopUpButton!
+	@IBOutlet var enterpriseBASICButton: NSPopUpButton!
+	@IBOutlet var enterpriseDOSButton: NSPopUpButton!
 
 	// MARK: - Macintosh properties
 	@IBOutlet var macintoshModelTypeButton: NSPopUpButton!
@@ -93,14 +99,20 @@ class MachinePicker: NSObject, NSTableViewDataSource, NSTableViewDelegate {
 		appleIIgsModelButton.selectItem(withTag: standardUserDefaults.integer(forKey: "new.appleIIgsModel"))
 		appleIIgsMemorySizeButton.selectItem(withTag: standardUserDefaults.integer(forKey: "new.appleIIgsMemorySize"))
 
+		// CPC settings
+		cpcModelTypeButton.selectItem(withTag: standardUserDefaults.integer(forKey: "new.cpcModel"))
+
 		// Electron settings
 		electronDFSButton.state = standardUserDefaults.bool(forKey: "new.electronDFS") ? .on : .off
 		electronADFSButton.state = standardUserDefaults.bool(forKey: "new.electronADFS") ? .on : .off
 		electronAP6Button.state = standardUserDefaults.bool(forKey: "new.electronAP6") ? .on : .off
 		electronSidewaysRAMButton.state = standardUserDefaults.bool(forKey: "new.electronSidewaysRAM") ? .on : .off
 
-		// CPC settings
-		cpcModelTypeButton.selectItem(withTag: standardUserDefaults.integer(forKey: "new.cpcModel"))
+		// Enterprise settings
+		enterpriseModelButton.selectItem(withTag: standardUserDefaults.integer(forKey: "new.enterpriseModel"))
+		enterpriseEXOSButton.selectItem(withTag: standardUserDefaults.integer(forKey: "new.enterpriseEXOSVersion"))
+		enterpriseBASICButton.selectItem(withTag: standardUserDefaults.integer(forKey: "new.enterpriseBASICVersion"))
+		enterpriseDOSButton.selectItem(withTag: standardUserDefaults.integer(forKey: "new.enterpriseDOS"))
 
 		// Macintosh settings
 		macintoshModelTypeButton.selectItem(withTag: standardUserDefaults.integer(forKey: "new.macintoshModel"))
@@ -143,14 +155,20 @@ class MachinePicker: NSObject, NSTableViewDataSource, NSTableViewDelegate {
 		standardUserDefaults.set(appleIIgsModelButton.selectedTag(), forKey: "new.appleIIgsModel")
 		standardUserDefaults.set(appleIIgsMemorySizeButton.selectedTag(), forKey: "new.appleIIgsMemorySize")
 
+		// CPC settings
+		standardUserDefaults.set(cpcModelTypeButton.selectedTag(), forKey: "new.cpcModel")
+
 		// Electron settings
 		standardUserDefaults.set(electronDFSButton.state == .on, forKey: "new.electronDFS")
 		standardUserDefaults.set(electronADFSButton.state == .on, forKey: "new.electronADFS")
 		standardUserDefaults.set(electronAP6Button.state == .on, forKey: "new.electronAP6")
 		standardUserDefaults.set(electronSidewaysRAMButton.state == .on, forKey: "new.electronSidewaysRAM")
 
-		// CPC settings
-		standardUserDefaults.set(cpcModelTypeButton.selectedTag(), forKey: "new.cpcModel")
+		// Enterprise settings
+		standardUserDefaults.set(enterpriseModelButton.selectedTag(), forKey: "new.enterpriseModel")
+		standardUserDefaults.set(enterpriseEXOSButton.selectedTag(), forKey: "new.enterpriseEXOSVersion")
+		standardUserDefaults.set(enterpriseBASICButton.selectedTag(), forKey: "new.enterpriseBASICVersion")
+		standardUserDefaults.set(enterpriseDOSButton.selectedTag(), forKey: "new.enterpriseDOS")
 
 		// Macintosh settings
 		standardUserDefaults.set(macintoshModelTypeButton.selectedTag(), forKey: "new.macintoshModel")
@@ -257,7 +275,40 @@ class MachinePicker: NSObject, NSTableViewDataSource, NSTableViewDelegate {
 					sidewaysRAM: electronSidewaysRAMButton.state == .on)
 
 			case "enterprise":
-				return CSStaticAnalyser(enterpriseModel: .model64)
+				var model: CSMachineEnterpriseModel = .model128
+				switch enterpriseModelButton.selectedItem!.tag {
+					case 64:	model = .model64
+					case 256:	model = .model256
+					case 128:	fallthrough
+					default:	model = .model128
+				}
+
+				var exos: CSMachineEnterpriseEXOS = .version21
+				switch enterpriseEXOSButton.selectedItem!.tag {
+					case 10:	exos = .version10
+					case 20:	exos = .version20
+					case 21:	fallthrough
+					default:	exos = .version21
+				}
+
+				var basic: CSMachineEnterpriseBASIC = .version21
+				switch enterpriseBASICButton.selectedTag() {
+					case 0:		basic = .none
+					case 10:	basic = .version10
+					case 11:	basic = .version11
+					case 21:	fallthrough
+					default:	basic = .version21
+				}
+
+				var dos: CSMachineEnterpriseDOS = .dosNone
+				switch enterpriseDOSButton.selectedTag() {
+					case 1:		dos = .DOSEXDOS
+					case 2:		dos = .DOSEPDOS
+					case 0:		fallthrough
+					default:	dos = .dosNone
+				}
+
+				return CSStaticAnalyser(enterpriseModel: model, exosVersion: exos, basicVersion: basic, dos: dos)
 
 			case "mac":
 				switch macintoshModelTypeButton.selectedItem!.tag {

From 0d165740ea585b2e450e320295a714e4448dacd8 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 22 Jun 2021 21:48:55 -0400
Subject: [PATCH 068/117] Honours memory size request.

---
 Machines/Enterprise/Enterprise.cpp | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index d1bae8b27..87fc56428 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -69,8 +69,21 @@ template <bool has_disk_controller> class ConcreteMachine:
 	public MachineTypes::MediaTarget,
 	public MachineTypes::ScanProducer,
 	public MachineTypes::TimedMachine {
+	private:
+		constexpr uint8_t min_ram_slot(const Analyser::Static::Enterprise::Target &target) {
+			size_t ram_size = 128*1024;
+			switch(target.model) {
+				case Analyser::Static::Enterprise::Target::Model::Enterprise64:		ram_size = 64*1024;		break;
+				case Analyser::Static::Enterprise::Target::Model::Enterprise128:	ram_size = 128*1024;	break;
+				case Analyser::Static::Enterprise::Target::Model::Enterprise256:	ram_size = 256*1024;	break;
+			}
+
+			return uint8_t(0x100 - ram_size / 0x4000);
+		}
+
 	public:
 		ConcreteMachine([[maybe_unused]] const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
+			min_ram_slot_(min_ram_slot(target)),
 			z80_(*this),
 			nick_(ram_.end() - 65536) {
 			// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
@@ -339,11 +352,11 @@ template <bool has_disk_controller> class ConcreteMachine:
 
 	private:
 		// MARK: - Memory layout
-		std::array<uint8_t, 128 * 1024> ram_;
+		std::array<uint8_t, 256 * 1024> ram_;
 		std::array<uint8_t, 64 * 1024> exos_;
 		std::array<uint8_t, 16 * 1024> basic_;
 		std::array<uint8_t, 32 * 1024> dos_;
-		const uint8_t min_ram_slot_ = uint8_t(0x100 - (ram_.size() / 0x4000));
+		const uint8_t min_ram_slot_;
 
 		const uint8_t *read_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
 		uint8_t *write_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};

From 2c2bb3765f3aa57931d6c9da57020651b30a5b8c Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 23 Jun 2021 19:32:34 -0400
Subject: [PATCH 069/117] Withdraws the EPDOS option.

At least for now; it's something to worry about later.
---
 Analyser/Static/Enterprise/Target.hpp         |  2 +-
 Machines/Enterprise/Enterprise.cpp            | 46 +++++++++----------
 .../Machine/StaticAnalyser/CSStaticAnalyser.h |  1 -
 .../StaticAnalyser/CSStaticAnalyser.mm        |  1 -
 .../Base.lproj/MachinePicker.xib              |  3 +-
 .../MachinePicker/MachinePicker.swift         |  1 -
 6 files changed, 25 insertions(+), 29 deletions(-)

diff --git a/Analyser/Static/Enterprise/Target.hpp b/Analyser/Static/Enterprise/Target.hpp
index 1785405c4..9200a3ce5 100644
--- a/Analyser/Static/Enterprise/Target.hpp
+++ b/Analyser/Static/Enterprise/Target.hpp
@@ -21,7 +21,7 @@ struct Target: public Analyser::Static::Target, public Reflection::StructImpl<Ta
 	ReflectableEnum(Model, Enterprise64, Enterprise128, Enterprise256);
 	ReflectableEnum(EXOSVersion, v10, v20, v21, v23, Any);
 	ReflectableEnum(BASICVersion, v10, v11, v21, Any, None);
-	ReflectableEnum(DOS, EPDOS, EXDOS, None);
+	ReflectableEnum(DOS, EXDOS, None);
 
 	Model model = Model::Enterprise128;
 	EXOSVersion exos_version = EXOSVersion::Any;
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 87fc56428..63e777253 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -140,8 +140,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 
 			// Possibly add in a DOS.
 			switch(target.dos) {
-				case Target::DOS::EPDOS:	request = request && ROM::Request(ROM::Name::EnterpriseEPDOS);	break;
-				case Target::DOS::EXDOS:	request = request && ROM::Request(ROM::Name::EnterpriseEXDOS);	break;
+				case Target::DOS::EXDOS:			request = request && ROM::Request(ROM::Name::EnterpriseEXDOS);	break;
 				default: break;
 			}
 
@@ -181,14 +180,16 @@ template <bool has_disk_controller> class ConcreteMachine:
 				}
 			}
 
-			// Extract the appropriate DOS ROM.
-			dos_.fill(0xff);
-			for(const auto rom_name: { ROM::Name::EnterpriseEPDOS, ROM::Name::EnterpriseEXDOS }) {
-				const auto dos = roms.find(rom_name);
-				if(dos != roms.end()) {
-					memcpy(dos_.data(), dos->second.data(), std::min(dos_.size(), dos->second.size()));
-					break;
-				}
+			// Extract the appropriate DOS ROMs.
+			epdos_rom_.fill(0xff);
+			const auto epdos = roms.find(ROM::Name::EnterpriseEPDOS);
+			if(epdos != roms.end()) {
+				memcpy(epdos_rom_.data(), epdos->second.data(), std::min(epdos_rom_.size(), epdos->second.size()));
+			}
+			exdos_rom_.fill(0xff);
+			const auto exdos = roms.find(ROM::Name::EnterpriseEXDOS);
+			if(exdos != roms.end()) {
+				memcpy(exdos_rom_.data(), exdos->second.data(), std::min(exdos_rom_.size(), exdos->second.size()));
 			}
 
 			// Seed key state.
@@ -355,7 +356,8 @@ template <bool has_disk_controller> class ConcreteMachine:
 		std::array<uint8_t, 256 * 1024> ram_;
 		std::array<uint8_t, 64 * 1024> exos_;
 		std::array<uint8_t, 16 * 1024> basic_;
-		std::array<uint8_t, 32 * 1024> dos_;
+		std::array<uint8_t, 16 * 1024> exdos_rom_;
+		std::array<uint8_t, 32 * 1024> epdos_rom_;
 		const uint8_t min_ram_slot_;
 
 		const uint8_t *read_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
@@ -365,20 +367,18 @@ template <bool has_disk_controller> class ConcreteMachine:
 		template <size_t slot> void page(uint8_t offset) {
 			pages_[slot] = offset;
 
-			if(offset < exos_.size() / 0x4000) {
-				page<slot>(&exos_[offset * 0x4000], nullptr);
-				return;
-			}
+#define Map(location, source)												\
+	if(offset >= location && offset < location + source.size() / 0x4000) {	\
+		page<slot>(&source[(offset - location) * 0x4000], nullptr);			\
+		return;																\
+	}
 
-			if(offset >= 16 && offset < 16 + basic_.size() / 0x4000) {
-				page<slot>(&basic_[(offset - 16) * 0x4000], nullptr);
-				return;
-			}
+			Map(0, exos_);
+			Map(16, basic_);
+			Map(32, exdos_rom_);
+			Map(48, epdos_rom_);
 
-			if(offset >= 32 && offset < 32 + dos_.size() / 0x4000) {
-				page<slot>(&dos_[(offset - 32) * 0x4000], nullptr);
-				return;
-			}
+#undef Map
 
 			// Of whatever size of RAM I've declared above, use only the final portion.
 			// This correlated with Nick always having been handed the final 64kb and,
diff --git a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h
index 11d6e9841..988fd9075 100644
--- a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h	
+++ b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.h	
@@ -62,7 +62,6 @@ typedef NS_ENUM(NSInteger, CSMachineEnterpriseBASIC) {
 
 typedef NS_ENUM(NSInteger, CSMachineEnterpriseDOS) {
 	CSMachineEnterpriseDOSEXDOS,
-	CSMachineEnterpriseDOSEPDOS,
 	CSMachineEnterpriseDOSNone,
 };
 
diff --git a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm
index 787f33d6c..805fff5d1 100644
--- a/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm	
+++ b/OSBindings/Mac/Clock Signal/Machine/StaticAnalyser/CSStaticAnalyser.mm	
@@ -161,7 +161,6 @@
 
 		switch(dos) {
 			case CSMachineEnterpriseDOSEXDOS:		target->dos = Target::DOS::EXDOS;					break;
-			case CSMachineEnterpriseDOSEPDOS:		target->dos = Target::DOS::EPDOS;					break;
 			default:
 			case CSMachineEnterpriseDOSNone:		target->dos = Target::DOS::None;					break;
 		}
diff --git a/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib b/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib
index 4b162af57..494e5dcdc 100644
--- a/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib	
+++ b/OSBindings/Mac/Clock Signal/MachinePicker/Base.lproj/MachinePicker.xib	
@@ -353,13 +353,12 @@ Gw
                                         </popUpButton>
                                         <popUpButton verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="syE-e7-TjU">
                                             <rect key="frame" x="57" y="89" width="83" height="25"/>
-                                            <popUpButtonCell key="cell" type="push" title="None" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" imageScaling="axesIndependently" inset="2" selectedItem="qoS-KO-iEZ" id="NvO-Zm-2Rq">
+                                            <popUpButtonCell key="cell" type="push" title="EXDOS" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" borderStyle="borderAndBezel" tag="1" imageScaling="axesIndependently" inset="2" selectedItem="8rP-2w-PdU" id="NvO-Zm-2Rq">
                                                 <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
                                                 <font key="font" metaFont="menu"/>
                                                 <menu key="menu" title="DOS" id="sdr-al-7mi">
                                                     <items>
                                                         <menuItem title="EXDOS" tag="1" id="8rP-2w-PdU"/>
-                                                        <menuItem title="EPDOS" tag="2" id="Ke7-AJ-8Rx"/>
                                                         <menuItem title="None" state="on" id="qoS-KO-iEZ"/>
                                                     </items>
                                                 </menu>
diff --git a/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift b/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift
index dbf8c0b2e..970200e2a 100644
--- a/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift	
+++ b/OSBindings/Mac/Clock Signal/MachinePicker/MachinePicker.swift	
@@ -303,7 +303,6 @@ class MachinePicker: NSObject, NSTableViewDataSource, NSTableViewDelegate {
 				var dos: CSMachineEnterpriseDOS = .dosNone
 				switch enterpriseDOSButton.selectedTag() {
 					case 1:		dos = .DOSEXDOS
-					case 2:		dos = .DOSEPDOS
 					case 0:		fallthrough
 					default:	dos = .dosNone
 				}

From 6c8b23e708b1961e91ce9dd4663149bd71337120 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 23 Jun 2021 19:35:47 -0400
Subject: [PATCH 070/117] Alters 4bpp mapping; adds character mode 4bpp and
 8bpp.

---
 Machines/Enterprise/Nick.cpp | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 6eb188ab7..ca19e753c 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -489,12 +489,12 @@ template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int
 			break;
 
 			case 4:
-				target[0] = palette_[((pixels[0] & 0x80) >> 4) | ((pixels[0] & 0x20) >> 3) | ((pixels[0] & 0x08) >> 2) | ((pixels[0] & 0x02) >> 1)];
-				target[1] = palette_[((pixels[0] & 0x40) >> 3) | ((pixels[0] & 0x10) >> 2) | ((pixels[0] & 0x04) >> 1) | ((pixels[0] & 0x01) >> 0)];
+				target[0] = palette_[((pixels[0] & 0xa0) >> 4) | ((pixels[0] & 0x0a) >> 1)];
+				target[1] = palette_[((pixels[0] & 0x50) >> 3) | ((pixels[0] & 0x05) >> 0)];
 
 				if constexpr (!is_lpixel) {
-					target[2] = palette_[((pixels[1] & 0x80) >> 4) | ((pixels[1] & 0x20) >> 3) | ((pixels[1] & 0x08) >> 2) | ((pixels[1] & 0x02) >> 1)];
-					target[3] = palette_[((pixels[1] & 0x40) >> 3) | ((pixels[1] & 0x10) >> 2) | ((pixels[1] & 0x04) >> 1) | ((pixels[1] & 0x01) >> 0)];
+					target[2] = palette_[((pixels[1] & 0xa0) >> 4) | ((pixels[1] & 0x0a) >> 1)];
+					target[3] = palette_[((pixels[1] & 0x50) >> 3) | ((pixels[1] & 0x05) >> 0)];
 
 					target += 2;
 				}
@@ -534,7 +534,6 @@ template <int bpp, int index_bits> void Nick::output_character(uint16_t *target,
 		switch(bpp) {
 			default:
 				assert(false);
-				// TODO: other BPPs are supported for character modes, I think.
 			break;
 
 			case 1: {
@@ -556,9 +555,19 @@ template <int bpp, int index_bits> void Nick::output_character(uint16_t *target,
 				target[1] = palette_[((pixels & 0x40) >> 5) | ((pixels & 0x04) >> 2)];
 				target[2] = palette_[((pixels & 0x20) >> 4) | ((pixels & 0x02) >> 1)];
 				target[3] = palette_[((pixels & 0x10) >> 3) | ((pixels & 0x01) >> 0)];
-
 				target += 4;
 			break;
+
+			case 4:
+				target[0] = palette_[((pixels & 0xa0) >> 4) | ((pixels & 0x0a) >> 1)];
+				target[1] = palette_[((pixels & 0x50) >> 3) | ((pixels & 0x05) >> 0)];
+				target += 2;
+			break;
+
+			case 8:
+				target[0] = mapped_colour(pixels);
+				++target;
+			break;
 		}
 	}
 }

From f98888824d1665d3d3dafd67ac41c3938dcd339a Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 24 Jun 2021 18:34:21 -0400
Subject: [PATCH 071/117] Switches to an overt active/inactive state machine.

---
 Machines/Enterprise/Nick.cpp | 399 +++++++++++++++++++----------------
 Machines/Enterprise/Nick.hpp |  24 ++-
 2 files changed, 233 insertions(+), 190 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index ca19e753c..5bbccb201 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -52,7 +52,9 @@ void Nick::write(uint16_t address, uint8_t value) {
 			}
 		break;
 		case 1:
-			flush_border();
+			if(output_type_ == OutputType::Border) {
+				set_output_type(OutputType::Border, true);
+			}
 			border_colour_ = mapped_colour(value);
 		break;
 		case 2:
@@ -68,7 +70,7 @@ void Nick::write(uint16_t address, uint8_t value) {
 				// I'm unclear whether I should also reset the horizontal counter
 				// (i.e. completely abandon current video phase).
 				lines_remaining_ = 0xff;
-				line_parameters_[1] |= 1;
+				should_reload_line_parameters_ = true;
 			}
 			line_parameter_control_ = value & 0xc0;
 		break;
@@ -79,9 +81,15 @@ uint8_t Nick::read([[maybe_unused]] uint16_t address) {
 	return 0xff;
 }
 
+//int c;
+
 void Nick::run_for(Cycles duration) {
 	constexpr int line_length = 912;
 
+#define check_margins()											\
+	if(window == left_margin_) is_sync_or_pixels_ = true;		\
+	if(window == right_margin_) is_sync_or_pixels_ = false;
+
 	int clocks_remaining = duration.as<int>();
 	while(clocks_remaining) {
 		// Determine how many cycles are left this line.
@@ -98,162 +106,197 @@ void Nick::run_for(Cycles duration) {
 		// Do nothing if a window boundary isn't crossed.
 		if(window == end_window) continue;
 
-		// If this is within the first 8 cycles of the line, [possibly] fetch
-		// the relevant part of the line parameters.
-		if(should_reload_line_parameters_ && window < 8) {
-			int fetch_spot = window;
-			while(fetch_spot < end_window && fetch_spot < 8) {
-				line_parameters_[(fetch_spot << 1)] = ram_[line_parameter_pointer_];
-				line_parameters_[(fetch_spot << 1) + 1] = ram_[line_parameter_pointer_ + 1];
-				line_parameter_pointer_ += 2;
-				++fetch_spot;
-			}
-
-			// TODO: when exactly does the interrupt output change? Am I a window too late? Or two too early?
-
-			// Special: set mode as soon as it's known. It'll be needed at the end of HSYNC.
-			if(window < 2 && fetch_spot >= 2) {
-				// Set length of mode line.
-				lines_remaining_ = line_parameters_[0];
-
-				// Set the new interrupt line output.
-				interrupt_line_ = line_parameters_[1] & 0x80;
-
-				// Determine the margins.
-				left_margin_ = line_parameters_[2] & 0x3f;
-				right_margin_ = line_parameters_[3] & 0x3f;
-
-				// Determine the mode and depth, and hence the column size.
-				mode_ = Mode((line_parameters_[1] >> 1)&7);
-				bpp_ = 1 << ((line_parameters_[1] >> 5)&3);
-				switch(mode_) {
-					default:
-					case Mode::Pixel:	column_size_ = 16 / bpp_;	break;
-					case Mode::CH64:
-					case Mode::CH128:
-					case Mode::CH256:
-					case Mode::LPixel:	column_size_ = 8 / bpp_;	break;
-					case Mode::Attr:	column_size_ = 8;			break;
-				}
-
-				// Act as if proper state transitions had occurred while HSYNC is being output.
-				if(mode_ == Mode::Vsync) {
-					state_ = State::Blank;
-				} else {
-					// The first ten windows are occupied by the horizontal sync and
-					// colour burst; if left signalled before then, begin in pixels.
-					state_ = left_margin_ > 10 ? State::Border : State::Pixels;
-				}
-			}
-
-			// If all parameters have been loaded, set appropriate fields.
-			if(fetch_spot == 8) {
-				should_reload_line_parameters_ = false;
-
-				// Determine the line data pointers.
-				line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
-				line_data_pointer_[1] = uint16_t(line_parameters_[6] | (line_parameters_[7] << 8));
-
-				// Populate the first eight colours of the palette.
-				for(int c = 0; c < 8; c++) {
-					palette_[c] = mapped_colour(line_parameters_[8 + c]);
-				}
-
-				switch(mode_) {
-					default:
-						assert(false);
-					case Mode::Vsync:
-					break;
-
-					// NB: LSBALT/MSBALT and ALTIND0/ALTIND1 appear to have opposite effects on palette selection.
-
-					case Mode::Pixel:
-					case Mode::LPixel:
-						// Use MSBALT and LSBALT to pick the alt_ind_palettes.
-						//
-						// LSBALT = b6 of params[2], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
-						// MSBALT = b7 of params[2], if set => character codes with bit 7 set should use palette indices 2 and 3.
-						two_colour_mask_ = 0xff &~ (((line_parameters_[2]&0x80) >> 7) | ((line_parameters_[2]&0x40) << 1));
-
-						alt_ind_palettes[0] = palette_;
-						alt_ind_palettes[2] = alt_ind_palettes[0] + ((line_parameters_[2] & 0x80) ? 2 : 0);
-
-						alt_ind_palettes[1] = alt_ind_palettes[0] + ((line_parameters_[2] & 0x40) ? 4 : 0);
-						alt_ind_palettes[3] = alt_ind_palettes[2] + ((line_parameters_[2] & 0x40) ? 4 : 0);
-
-						line_data_per_column_increments_[0] = 1 + (mode_ == Mode::Pixel);
-						line_data_per_column_increments_[1] = 0;
-					break;
-
-					case Mode::CH64:
-					case Mode::CH128:
-					case Mode::CH256:
-						// Use ALTIND0 and ALTIND1 to pick the alt_ind_palettes.
-						//
-						// ALTIND1 = b6 of params[3], if set => character codes with bit 7 set should use palette indices 2 and 3.
-						// ALTIND0 = b7 of params[3], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
-						alt_ind_palettes[0] = palette_;
-						alt_ind_palettes[2] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x40) ? 2 : 0);
-
-						alt_ind_palettes[1] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x80) ? 4 : 0);
-						alt_ind_palettes[3] = alt_ind_palettes[2] + ((line_parameters_[3] & 0x80) ? 4 : 0);
-
-						line_data_per_column_increments_[0] = 1;
-						line_data_per_column_increments_[1] = 0;
-					break;
-
-					case Mode::Attr:
-						line_data_per_column_increments_[0] = 1;
-						line_data_per_column_increments_[1] = 1;
-					break;
-				}
-			}
-		}
-
 		// HSYNC is signalled for four windows at the start of the line.
-		// I currently belive this happens regardless of Vsync mode.
-		if(window < 4 && end_window >= 4) {
-			crt_.output_sync(4*16);
-			window = 4;
+		// I currently believe this happens regardless of Vsync mode.
+		//
+		// This is also when the non-palette line parameters
+		// are loaded, if appropriate.
+		if(!window) set_output_type(OutputType::Sync);
+		while(window < 4 && window < end_window) {
+			if(should_reload_line_parameters_) {
+				switch(window) {
+					// First slot: line count, mode and interrupt flag.
+					case 0:
+						assert(!(line_parameter_pointer_&0xf));
+						lines_remaining_ = ram_[line_parameter_pointer_];
+						++line_parameter_pointer_;
+
+						// Set the new interrupt line output.
+						interrupt_line_ = ram_[line_parameter_pointer_] & 0x80;
+
+						// Determine the mode and depth, and hence the column size.
+						mode_ = Mode((ram_[line_parameter_pointer_] >> 1)&7);
+						bpp_ = 1 << ((ram_[line_parameter_pointer_] >> 5)&3);
+						switch(mode_) {
+							default:
+							case Mode::Pixel:
+								column_size_ = 16 / bpp_;
+								line_data_per_column_increments_[0] = 2;
+								line_data_per_column_increments_[1] = 0;
+							break;
+
+							case Mode::LPixel:
+								column_size_ = 8 / bpp_;
+								line_data_per_column_increments_[0] = 1;
+								line_data_per_column_increments_[1] = 0;
+							break;
+
+							case Mode::CH64:
+							case Mode::CH128:
+							case Mode::CH256:
+								column_size_ = 8;
+								line_data_per_column_increments_[0] = 1;
+								line_data_per_column_increments_[1] = 0;
+							break;
+
+							case Mode::Attr:
+								column_size_ = 8;
+								line_data_per_column_increments_[0] = 1;
+								line_data_per_column_increments_[1] = 1;
+							break;
+						}
+
+						vres_ = ram_[line_parameter_pointer_] & 0x10;
+						reload_line_parameter_pointer_ = ram_[line_parameter_pointer_] & 0x01;
+						++line_parameter_pointer_;
+					break;
+
+					// Second slot: margins and ALT/IND bits.
+					case 1:
+						// Determine the margins.
+						left_margin_ = ram_[line_parameter_pointer_] & 0x3f;
+						right_margin_ = ram_[(line_parameter_pointer_+1) & 0xffff] & 0x3f;
+
+						// Set up the alternative palettes,
+						switch(mode_) {
+							default:
+							break;
+
+							// NB: LSBALT/MSBALT and ALTIND0/ALTIND1 appear to have opposite effects on palette selection.
+
+							case Mode::Pixel:
+							case Mode::LPixel: {
+								const uint8_t flags = ram_[line_parameter_pointer_];
+
+								// Use MSBALT and LSBALT to pick the alt_ind_palettes.
+								//
+								// LSBALT = b6 of params[2], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
+								// MSBALT = b7 of params[2], if set => character codes with bit 7 set should use palette indices 2 and 3.
+								two_colour_mask_ = 0xff &~ (((flags&0x80) >> 7) | ((flags&0x40) << 1));
+
+								alt_ind_palettes[0] = palette_;
+								alt_ind_palettes[2] = alt_ind_palettes[0] + ((flags & 0x80) ? 2 : 0);
+
+								alt_ind_palettes[1] = alt_ind_palettes[0] + ((flags & 0x40) ? 4 : 0);
+								alt_ind_palettes[3] = alt_ind_palettes[2] + ((flags & 0x40) ? 4 : 0);
+							} break;
+
+							case Mode::CH64:
+							case Mode::CH128:
+							case Mode::CH256: {
+								const uint8_t flags = ram_[(line_parameter_pointer_+1) & 0xffff];
+
+								// Use ALTIND0 and ALTIND1 to pick the alt_ind_palettes.
+								//
+								// ALTIND1 = b6 of params[3], if set => character codes with bit 7 set should use palette indices 2 and 3.
+								// ALTIND0 = b7 of params[3], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
+								alt_ind_palettes[0] = palette_;
+								alt_ind_palettes[2] = alt_ind_palettes[0] + ((flags & 0x40) ? 2 : 0);
+
+								alt_ind_palettes[1] = alt_ind_palettes[0] + ((flags & 0x80) ? 4 : 0);
+								alt_ind_palettes[3] = alt_ind_palettes[2] + ((flags & 0x80) ? 4 : 0);
+							} break;
+						}
+
+						line_parameter_pointer_ += 2;
+					break;
+
+					// Third slot: Line data pointer 1.
+					case 2:
+						start_line_data_pointer_[0] = ram_[line_parameter_pointer_];
+						++line_parameter_pointer_;
+						start_line_data_pointer_[0] |= ram_[line_parameter_pointer_] << 8;
+						++line_parameter_pointer_;
+
+						line_data_pointer_[0] = start_line_data_pointer_[0];
+					break;
+
+					// Fourth slot: Line data pointer 2.
+					case 3:
+						start_line_data_pointer_[1] = ram_[line_parameter_pointer_];
+						++line_parameter_pointer_;
+						start_line_data_pointer_[1] |= ram_[line_parameter_pointer_] << 8;
+						++line_parameter_pointer_;
+
+						line_data_pointer_[1] = start_line_data_pointer_[1];
+					break;
+				}
+			}
+
+			++output_duration_;
+			++window;
+			check_margins();
+		}
+		if(window == 4) {
+			if(mode_ == Mode::Vsync) {
+				// Skip the palette.
+				if(should_reload_line_parameters_) line_parameter_pointer_ += 8;
+				should_reload_line_parameters_ = false;
+				set_output_type(is_sync_or_pixels_ ? OutputType::Sync : OutputType::Blank);
+			} else {
+				set_output_type(OutputType::Blank);
+			}
 		}
 
 		// Deal with vsync mode out here.
 		if(mode_ == Mode::Vsync) {
 			if(window >= 4) {
 				while(window < end_window) {
+					// Skip straight to the next event.
 					int next_event = end_window;
 					if(window < left_margin_) next_event = std::min(next_event, left_margin_);
 					if(window < right_margin_) next_event = std::min(next_event, right_margin_);
-
-					if(state_ == State::Blank) {
-						crt_.output_blank((next_event - window)*16);
-					} else {
-						crt_.output_sync((next_event - window)*16);
-					}
-
+					output_duration_ += next_event - window;
 					window = next_event;
-					if(window == left_margin_) state_ = State::Sync;
-					if(window == right_margin_) state_ = State::Blank;
+
+					check_margins();
+					set_output_type(is_sync_or_pixels_ ? OutputType::Sync : OutputType::Blank);
 				}
 			}
 		} else {
 			// If present then the colour burst is output for the period from
 			// the start of window 6 to the end of window 10.
-			if(window < 10 && end_window >= 10) {
-				crt_.output_blank(2*16);
-				crt_.output_colour_burst(4*16, 0);	// TODO: try to determine actual phase.
-				window = 10;
+			//
+			// The first 8 palette entries also need to be fetched here.
+			while(window < 10 && window < end_window) {
+				if(window == 6) {
+					set_output_type(OutputType::ColourBurst);
+				}
+
+				if(should_reload_line_parameters_ && window < 8) {
+					const int base = (window - 4) << 1;
+					palette_[base] = mapped_colour(ram_[line_parameter_pointer_]);
+					++line_parameter_pointer_;
+					palette_[base+1] = mapped_colour(ram_[line_parameter_pointer_]);
+					++line_parameter_pointer_;
+				} else {
+					should_reload_line_parameters_ = false;
+				}
+
+				++output_duration_;
+				++window;
 			}
 
 			if(window >= 10) {
+				if(window == 10) set_output_type(is_sync_or_pixels_ ? OutputType::Pixels : OutputType::Border);
+
 				while(window < end_window) {
 					int next_event = end_window;
 					if(window < left_margin_) next_event = std::min(next_event, left_margin_);
 					if(window < right_margin_) next_event = std::min(next_event, right_margin_);
 
-					if(state_ == State::Border) {
-						border_duration_ += next_event - window;
-					} else {
+					if(is_sync_or_pixels_) {
+
 #define DispatchBpp(func) \
 	switch(bpp_) {	\
 		default:	\
@@ -272,8 +315,10 @@ void Nick::run_for(Cycles duration) {
 
 						int columns_remaining = next_event - window;
 						while(columns_remaining) {
-							if(!allocated_pointer_) {
-								flush_pixels();
+							if(!pixel_pointer_) {
+								if(output_duration_) {
+									set_output_type(OutputType::Pixels, true);
+								}
 								pixel_pointer_ = allocated_pointer_ = reinterpret_cast<uint16_t *>(crt_.begin_data(allocation_size));
 							}
 
@@ -291,9 +336,9 @@ void Nick::run_for(Cycles duration) {
 								}
 
 								pixel_pointer_ += output_duration * column_size_;
-								pixel_duration_ += output_duration;
+								output_duration_ += output_duration;
 								if(pixel_pointer_ - allocated_pointer_ == allocation_size) {
-									flush_pixels();
+									set_output_type(OutputType::Pixels, true);
 								}
 								columns_remaining -= output_duration;
 							} else {
@@ -302,14 +347,11 @@ void Nick::run_for(Cycles duration) {
 								line_data_pointer_[0] += columns_remaining * line_data_per_column_increments_[0];
 								line_data_pointer_[1] += columns_remaining * line_data_per_column_increments_[1];
 
-								// Advance pixel pointer, so as to be able to supply something
-								// convincing to the CRT as to the number of samples that would have
-								// been provided, and skip asking for further allocations for now.
-								pixel_pointer_ += columns_remaining * column_size_;
-								pixel_duration_ += columns_remaining;
+								output_duration_ += columns_remaining;
 								columns_remaining = 0;
 							}
 						}
+
 #undef attr
 #undef ch64
 #undef ch128
@@ -317,38 +359,26 @@ void Nick::run_for(Cycles duration) {
 #undef pixel
 #undef lpixel
 #undef DispatchBpp
+					} else {
+						output_duration_ += next_event - window;
 					}
 
 					window = next_event;
-					if(window == left_margin_) {
-						flush_border();
-						state_ = State::Pixels;
-					}
-					if(window == right_margin_) {
-						flush_pixels();
-						state_ = State::Border;
-					}
-				}
-			}
-
-			// Finish up the line.
-			if(!horizontal_counter_) {
-				if(state_ == State::Border) {
-					flush_border();
-				} else {
-					flush_pixels();
+					check_margins();
+					set_output_type(is_sync_or_pixels_ ? OutputType::Pixels : OutputType::Border);
 				}
 			}
 		}
 
 		// Check for end of line.
 		if(!horizontal_counter_) {
+//			++c;
 			++lines_remaining_;
 			if(!lines_remaining_) {
 				should_reload_line_parameters_ = true;
 
 				// Check for end-of-frame.
-				if(line_parameters_[1] & 1) {
+				if(reload_line_parameter_pointer_) {
 					line_parameter_pointer_ = line_parameter_base_;
 				}
 			}
@@ -359,22 +389,22 @@ void Nick::run_for(Cycles duration) {
 				case Mode::CH64:
 				case Mode::CH128:
 				case Mode::CH256:
-					line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
+					line_data_pointer_[0] = start_line_data_pointer_[0];
 					++line_data_pointer_[1];
 				break;
 
 				case Mode::Attr:
 					// Reload the attribute address if VRES is set.
-					if(line_parameters_[1] & 0x10) {
-						line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
+					if(vres_) {
+						line_data_pointer_[0] = start_line_data_pointer_[0];
 					}
 				break;
 
 				case Mode::Pixel:
 				case Mode::LPixel:
 					// If VRES is clear, reload the pixel address.
-					if(!(line_parameters_[1] & 0x10)) {
-						line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
+					if(!vres_) {
+						line_data_pointer_[0] = start_line_data_pointer_[0];
 					}
 				break;
 			}
@@ -382,21 +412,32 @@ void Nick::run_for(Cycles duration) {
 	}
 }
 
-void Nick::flush_border() {
-	if(!border_duration_) return;
+void Nick::set_output_type(OutputType type, bool force_flush) {
+	if(type == output_type_ && !force_flush) {
+		return;
+	}
+	if(output_duration_) {
+		switch(output_type_) {
+			case OutputType::Border: {
+				uint16_t *const colour_pointer = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
+				if(colour_pointer) *colour_pointer = border_colour_;
+				crt_.output_level(output_duration_*16);
+			} break;
 
-	uint16_t *const colour_pointer = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
-	if(colour_pointer) *colour_pointer = border_colour_;
-	crt_.output_level(border_duration_*16);
-	border_duration_ = 0;
-}
+			case OutputType::Pixels: {
+				crt_.output_data(output_duration_*16, size_t(output_duration_*column_size_));
+				pixel_pointer_ = nullptr;
+				allocated_pointer_ = nullptr;
+			} break;
 
-void Nick::flush_pixels() {
-	if(!pixel_duration_) return;
-	crt_.output_data(pixel_duration_*16, size_t(pixel_pointer_ - allocated_pointer_));
-	pixel_duration_ = 0;
-	pixel_pointer_ = nullptr;
-	allocated_pointer_ = nullptr;
+			case OutputType::Sync:			crt_.output_sync(output_duration_*16);				break;
+			case OutputType::Blank:			crt_.output_blank(output_duration_*16);				break;
+			case OutputType::ColourBurst:	crt_.output_colour_burst(output_duration_*16, 0);	break;
+		}
+	}
+
+	output_duration_ = 0;
+	output_type_ = type;
 }
 
 // MARK: - Sequence points.
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index cb8f7431b..31911e90d 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -49,9 +49,9 @@ class Nick {
 		// Ephemerals, related to current video position.
 		int horizontal_counter_ = 0;
 		uint16_t line_parameter_pointer_ = 0x0000;
-		uint8_t line_parameters_[16];
 		bool should_reload_line_parameters_ = true;
 		uint16_t line_data_pointer_[2];
+		uint16_t start_line_data_pointer_[2];
 
 		// Current mode line parameters.
 		uint8_t lines_remaining_ = 0x00;
@@ -68,27 +68,29 @@ class Nick {
 			Unused,
 			LPixel,
 		} mode_ = Mode::Vsync;
-		enum class State {
-			Sync,
-			Border,
-			Pixels,
-			Blank,
-		} state_ = State::Sync;
+		bool is_sync_or_pixels_ = false;
 		int bpp_ = 0;
 		int column_size_ = 0;
 		bool interrupt_line_ = true;
 		int line_data_per_column_increments_[2] = {0, 0};
+		bool vres_ = false;
+		bool reload_line_parameter_pointer_ = false;
 
 		// An accumulator for border output regions.
 		int border_duration_ = 0;
-		void flush_border();
 
 		// The destination for new pixels.
-		static constexpr int allocation_size = 80;
+		static constexpr int allocation_size = 320;
 		static_assert((allocation_size % 16) == 0, "Allocation size must be a multiple of 16");
 		uint16_t *pixel_pointer_ = nullptr, *allocated_pointer_ = nullptr;
-		int pixel_duration_ = 0;
-		void flush_pixels();
+
+		// Output transitions.
+		enum class OutputType {
+			Sync, Blank, Pixels, Border, ColourBurst
+		};
+		void set_output_type(OutputType, bool force_flush = false);
+		int output_duration_ = 0;
+		OutputType output_type_ = OutputType::Sync;
 
 		// Current palette.
 		uint16_t palette_[16]{};

From 6e616972a51d0e7cb139114222f0ef068e741f40 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 24 Jun 2021 18:55:15 -0400
Subject: [PATCH 072/117] Better binds margin tests to window movements;
 simplifies line parameter addressing.

---
 Machines/Enterprise/Nick.cpp | 75 ++++++++++++++++--------------------
 1 file changed, 33 insertions(+), 42 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 5bbccb201..2d5712fe4 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -86,7 +86,8 @@ uint8_t Nick::read([[maybe_unused]] uint16_t address) {
 void Nick::run_for(Cycles duration) {
 	constexpr int line_length = 912;
 
-#define check_margins()											\
+#define add_window(x)											\
+	window += x;												\
 	if(window == left_margin_) is_sync_or_pixels_ = true;		\
 	if(window == right_margin_) is_sync_or_pixels_ = false;
 
@@ -117,16 +118,15 @@ void Nick::run_for(Cycles duration) {
 				switch(window) {
 					// First slot: line count, mode and interrupt flag.
 					case 0:
-						assert(!(line_parameter_pointer_&0xf));
+						// Byte 0: lines remaining.
 						lines_remaining_ = ram_[line_parameter_pointer_];
-						++line_parameter_pointer_;
 
 						// Set the new interrupt line output.
-						interrupt_line_ = ram_[line_parameter_pointer_] & 0x80;
+						interrupt_line_ = ram_[line_parameter_pointer_ + 1] & 0x80;
 
 						// Determine the mode and depth, and hence the column size.
-						mode_ = Mode((ram_[line_parameter_pointer_] >> 1)&7);
-						bpp_ = 1 << ((ram_[line_parameter_pointer_] >> 5)&3);
+						mode_ = Mode((ram_[line_parameter_pointer_ + 1] >> 1)&7);
+						bpp_ = 1 << ((ram_[line_parameter_pointer_ + 1] >> 5)&3);
 						switch(mode_) {
 							default:
 							case Mode::Pixel:
@@ -156,16 +156,15 @@ void Nick::run_for(Cycles duration) {
 							break;
 						}
 
-						vres_ = ram_[line_parameter_pointer_] & 0x10;
-						reload_line_parameter_pointer_ = ram_[line_parameter_pointer_] & 0x01;
-						++line_parameter_pointer_;
+						vres_ = ram_[line_parameter_pointer_ + 1] & 0x10;
+						reload_line_parameter_pointer_ = ram_[line_parameter_pointer_ + 1] & 0x01;
 					break;
 
 					// Second slot: margins and ALT/IND bits.
 					case 1:
 						// Determine the margins.
-						left_margin_ = ram_[line_parameter_pointer_] & 0x3f;
-						right_margin_ = ram_[(line_parameter_pointer_+1) & 0xffff] & 0x3f;
+						left_margin_ = ram_[line_parameter_pointer_ + 2] & 0x3f;
+						right_margin_ = ram_[line_parameter_pointer_ + 3] & 0x3f;
 
 						// Set up the alternative palettes,
 						switch(mode_) {
@@ -176,7 +175,7 @@ void Nick::run_for(Cycles duration) {
 
 							case Mode::Pixel:
 							case Mode::LPixel: {
-								const uint8_t flags = ram_[line_parameter_pointer_];
+								const uint8_t flags = ram_[line_parameter_pointer_ + 2];
 
 								// Use MSBALT and LSBALT to pick the alt_ind_palettes.
 								//
@@ -194,7 +193,7 @@ void Nick::run_for(Cycles duration) {
 							case Mode::CH64:
 							case Mode::CH128:
 							case Mode::CH256: {
-								const uint8_t flags = ram_[(line_parameter_pointer_+1) & 0xffff];
+								const uint8_t flags = ram_[line_parameter_pointer_ + 3];
 
 								// Use ALTIND0 and ALTIND1 to pick the alt_ind_palettes.
 								//
@@ -207,26 +206,20 @@ void Nick::run_for(Cycles duration) {
 								alt_ind_palettes[3] = alt_ind_palettes[2] + ((flags & 0x80) ? 4 : 0);
 							} break;
 						}
-
-						line_parameter_pointer_ += 2;
 					break;
 
 					// Third slot: Line data pointer 1.
 					case 2:
-						start_line_data_pointer_[0] = ram_[line_parameter_pointer_];
-						++line_parameter_pointer_;
-						start_line_data_pointer_[0] |= ram_[line_parameter_pointer_] << 8;
-						++line_parameter_pointer_;
+						start_line_data_pointer_[0] = ram_[line_parameter_pointer_ + 4];
+						start_line_data_pointer_[0] |= ram_[line_parameter_pointer_ + 5] << 8;
 
 						line_data_pointer_[0] = start_line_data_pointer_[0];
 					break;
 
 					// Fourth slot: Line data pointer 2.
 					case 3:
-						start_line_data_pointer_[1] = ram_[line_parameter_pointer_];
-						++line_parameter_pointer_;
-						start_line_data_pointer_[1] |= ram_[line_parameter_pointer_] << 8;
-						++line_parameter_pointer_;
+						start_line_data_pointer_[1] = ram_[line_parameter_pointer_ + 6];
+						start_line_data_pointer_[1] |= ram_[line_parameter_pointer_ + 7] << 8;
 
 						line_data_pointer_[1] = start_line_data_pointer_[1];
 					break;
@@ -234,14 +227,10 @@ void Nick::run_for(Cycles duration) {
 			}
 
 			++output_duration_;
-			++window;
-			check_margins();
+			add_window(1);
 		}
 		if(window == 4) {
 			if(mode_ == Mode::Vsync) {
-				// Skip the palette.
-				if(should_reload_line_parameters_) line_parameter_pointer_ += 8;
-				should_reload_line_parameters_ = false;
 				set_output_type(is_sync_or_pixels_ ? OutputType::Sync : OutputType::Blank);
 			} else {
 				set_output_type(OutputType::Blank);
@@ -256,10 +245,9 @@ void Nick::run_for(Cycles duration) {
 					int next_event = end_window;
 					if(window < left_margin_) next_event = std::min(next_event, left_margin_);
 					if(window < right_margin_) next_event = std::min(next_event, right_margin_);
-					output_duration_ += next_event - window;
-					window = next_event;
 
-					check_margins();
+					output_duration_ += next_event - window;
+					add_window(next_event - window);
 					set_output_type(is_sync_or_pixels_ ? OutputType::Sync : OutputType::Blank);
 				}
 			}
@@ -275,20 +263,18 @@ void Nick::run_for(Cycles duration) {
 
 				if(should_reload_line_parameters_ && window < 8) {
 					const int base = (window - 4) << 1;
-					palette_[base] = mapped_colour(ram_[line_parameter_pointer_]);
-					++line_parameter_pointer_;
-					palette_[base+1] = mapped_colour(ram_[line_parameter_pointer_]);
-					++line_parameter_pointer_;
-				} else {
-					should_reload_line_parameters_ = false;
+					palette_[base] = mapped_colour(ram_[line_parameter_pointer_ + base + 8]);
+					palette_[base + 1] = mapped_colour(ram_[line_parameter_pointer_ + base + 9]);
 				}
 
 				++output_duration_;
-				++window;
+				add_window(1);
 			}
 
 			if(window >= 10) {
-				if(window == 10) set_output_type(is_sync_or_pixels_ ? OutputType::Pixels : OutputType::Border);
+				if(window == 10) {
+					set_output_type(is_sync_or_pixels_ ? OutputType::Pixels : OutputType::Border);
+				}
 
 				while(window < end_window) {
 					int next_event = end_window;
@@ -363,8 +349,7 @@ void Nick::run_for(Cycles duration) {
 						output_duration_ += next_event - window;
 					}
 
-					window = next_event;
-					check_margins();
+					add_window(next_event - window);
 					set_output_type(is_sync_or_pixels_ ? OutputType::Pixels : OutputType::Border);
 				}
 			}
@@ -372,7 +357,6 @@ void Nick::run_for(Cycles duration) {
 
 		// Check for end of line.
 		if(!horizontal_counter_) {
-//			++c;
 			++lines_remaining_;
 			if(!lines_remaining_) {
 				should_reload_line_parameters_ = true;
@@ -380,7 +364,11 @@ void Nick::run_for(Cycles duration) {
 				// Check for end-of-frame.
 				if(reload_line_parameter_pointer_) {
 					line_parameter_pointer_ = line_parameter_base_;
+				} else {
+					line_parameter_pointer_ += 16;
 				}
+			} else {
+				should_reload_line_parameters_ = false;
 			}
 
 			// Deal with VRES and other address reloading, dependant upon mode.
@@ -410,6 +398,9 @@ void Nick::run_for(Cycles duration) {
 			}
 		}
 	}
+
+#undef add_window
+
 }
 
 void Nick::set_output_type(OutputType type, bool force_flush) {

From 9230cf17261c2a0b274413d48642ebee631a4c66 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 24 Jun 2021 20:28:50 -0400
Subject: [PATCH 073/117] Corrects bug when left_ or right_margin_ = 0.

---
 Machines/Enterprise/Nick.cpp | 33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 2d5712fe4..7ff7c3035 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -14,18 +14,29 @@ namespace  {
 
 uint16_t mapped_colour(uint8_t source) {
 	// On the Enterprise, red and green are 3-bit quantities; blue is a 2-bit quantity.
-	const int red	= ((source&0x01) << 2) | ((source&0x08) >> 2) | ((source&0x40) >> 6);
-	const int green	= ((source&0x02) << 1) | ((source&0x10) >> 3) | ((source&0x80) >> 7);
-	const int blue	= ((source&0x04) >> 1) | ((source&0x20) >> 5);
+	int red		= ((source&0x01) << 2) | ((source&0x08) >> 2) | ((source&0x40) >> 6);
+	int green	= ((source&0x02) << 1) | ((source&0x10) >> 3) | ((source&0x80) >> 7);
+	int blue	= ((source&0x04) >> 1) | ((source&0x20) >> 5);
+
+	assert(red <= 7);
+	assert(green <= 7);
+	assert(blue <= 3);
+
+	red = (red << 1) + (red >> 3);
+	green = (green << 1) + (green >> 3);
+	blue = (blue << 2) + blue;
+
+	assert(red <= 15);
+	assert(green <= 15);
+	assert(blue <= 15);
 
 	// Duplicate bits where necessary to map to a full 4-bit range per channel.
 	const uint8_t parts[2] = {
 		uint8_t(
-			(red << 1) + ((red&0x4) >> 3)
+			red
 		),
 		uint8_t(
-			(green << 5) + ((green&0x4) << 2) +
-			(blue << 2) + blue
+			(green << 4) + blue
 		)
 	};
 	return *reinterpret_cast<const uint16_t *>(parts);
@@ -112,7 +123,15 @@ void Nick::run_for(Cycles duration) {
 		//
 		// This is also when the non-palette line parameters
 		// are loaded, if appropriate.
-		if(!window) set_output_type(OutputType::Sync);
+		if(!window) {
+			set_output_type(OutputType::Sync);
+
+			// There's no increment to get to 0, it happens when the horizontal_counter_
+			// is reset. So test for active bit effect manually.
+			if(!left_margin_) is_sync_or_pixels_ = true;
+			if(!right_margin_) is_sync_or_pixels_ = false;
+		}
+
 		while(window < 4 && window < end_window) {
 			if(should_reload_line_parameters_) {
 				switch(window) {

From 520c3c921833d3d8efaf973f0e353bb8b6123b32 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 24 Jun 2021 20:59:04 -0400
Subject: [PATCH 074/117] Corrects colour deserialisation.

Long story short: the documentation I'm reading inexplicably lists the bits in reverse order. Luckily, a lot of the other documentation doesn't.
---
 Machines/Enterprise/Nick.cpp | 135 +++++++++++++----------------------
 1 file changed, 48 insertions(+), 87 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 7ff7c3035..933376a73 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -97,6 +97,8 @@ uint8_t Nick::read([[maybe_unused]] uint16_t address) {
 void Nick::run_for(Cycles duration) {
 	constexpr int line_length = 912;
 
+	// TODO: test here for window < 57? Or maybe just nudge up left_/right_margin_ if they
+	// exactly equal 57?
 #define add_window(x)											\
 	window += x;												\
 	if(window == left_margin_) is_sync_or_pixels_ = true;		\
@@ -282,6 +284,7 @@ void Nick::run_for(Cycles duration) {
 
 				if(should_reload_line_parameters_ && window < 8) {
 					const int base = (window - 4) << 1;
+					assert(base < 7);
 					palette_[base] = mapped_colour(ram_[line_parameter_pointer_ + base + 8]);
 					palette_[base + 1] = mapped_colour(ram_[line_parameter_pointer_ + base + 9]);
 				}
@@ -480,6 +483,33 @@ Outputs::Display::ScanStatus Nick::get_scaled_scan_status() const {
 
 // MARK: - Specific pixel outputters.
 
+#define output1bpp(x)	\
+	target[0] = palette[(x & 0x80) >> 7];	\
+	target[1] = palette[(x & 0x40) >> 6];	\
+	target[2] = palette[(x & 0x20) >> 5];	\
+	target[3] = palette[(x & 0x10) >> 4];	\
+	target[4] = palette[(x & 0x08) >> 3];	\
+	target[5] = palette[(x & 0x04) >> 2];	\
+	target[6] = palette[(x & 0x02) >> 1];	\
+	target[7] = palette[(x & 0x01) >> 0];	\
+	target += 8
+
+#define output2bpp(x)	\
+	target[0] = palette_[((x & 0x80) >> 7) | ((x & 0x08) >> 2)];	\
+	target[1] = palette_[((x & 0x40) >> 6) | ((x & 0x04) >> 1)];	\
+	target[2] = palette_[((x & 0x20) >> 5) | ((x & 0x02) >> 0)];	\
+	target[3] = palette_[((x & 0x10) >> 4) | ((x & 0x01) << 1)];	\
+	target += 4
+
+#define output4bpp(x)	\
+	target[0] = palette_[((x & 0x02) << 2) | ((x & 0x20) >> 3) | ((x & 0x08) >> 2) | ((x & 0x80) >> 7)];	\
+	target[1] = palette_[((x & 0x01) << 3) | ((x & 0x10) >> 2) | ((x & 0x04) >> 1) | ((x & 0x40) >> 6)];	\
+	target += 2
+
+#define output8bpp(x)	\
+	target[0] = mapped_colour(x);	\
+	++target
+
 template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int columns) {
 	static_assert(bpp == 1 || bpp == 2 || bpp == 4 || bpp == 8);
 
@@ -492,76 +522,34 @@ template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int
 			case 1: {
 				const uint16_t *palette = alt_ind_palettes[((pixels[0] >> 6) & 0x02) | (pixels[0]&1)];
 				pixels[0] &= two_colour_mask_;
-
-				target[0] = palette[(pixels[0] & 0x80) >> 7];
-				target[1] = palette[(pixels[0] & 0x40) >> 6];
-				target[2] = palette[(pixels[0] & 0x20) >> 5];
-				target[3] = palette[(pixels[0] & 0x10) >> 4];
-				target[4] = palette[(pixels[0] & 0x08) >> 3];
-				target[5] = palette[(pixels[0] & 0x04) >> 2];
-				target[6] = palette[(pixels[0] & 0x02) >> 1];
-				target[7] = palette[(pixels[0] & 0x01) >> 0];
+				output1bpp(pixels[0]);
 
 				if constexpr (!is_lpixel) {
 					palette = alt_ind_palettes[((pixels[1] >> 6) & 0x02) | (pixels[1]&1)];
 					pixels[1] &= two_colour_mask_;
-
-					target[8] = palette[(pixels[1] & 0x80) >> 7];
-					target[9] = palette[(pixels[1] & 0x40) >> 6];
-					target[10] = palette[(pixels[1] & 0x20) >> 5];
-					target[11] = palette[(pixels[1] & 0x10) >> 4];
-					target[12] = palette[(pixels[1] & 0x08) >> 3];
-					target[13] = palette[(pixels[1] & 0x04) >> 2];
-					target[14] = palette[(pixels[1] & 0x02) >> 1];
-					target[15] = palette[(pixels[1] & 0x01) >> 0];
-
-					target += 8;
+					output1bpp(pixels[1]);
 				}
-
-				target += 8;
 			} break;
 
 			case 2:
-				target[0] = palette_[((pixels[0] & 0x80) >> 6) | ((pixels[0] & 0x08) >> 3)];
-				target[1] = palette_[((pixels[0] & 0x40) >> 5) | ((pixels[0] & 0x04) >> 2)];
-				target[2] = palette_[((pixels[0] & 0x20) >> 4) | ((pixels[0] & 0x02) >> 1)];
-				target[3] = palette_[((pixels[0] & 0x10) >> 3) | ((pixels[0] & 0x01) >> 0)];
-
+				output2bpp(pixels[0]);
 				if constexpr (!is_lpixel) {
-					target[4] = palette_[((pixels[1] & 0x80) >> 6) | ((pixels[1] & 0x08) >> 3)];
-					target[5] = palette_[((pixels[1] & 0x40) >> 5) | ((pixels[1] & 0x04) >> 2)];
-					target[6] = palette_[((pixels[1] & 0x20) >> 4) | ((pixels[1] & 0x02) >> 1)];
-					target[7] = palette_[((pixels[1] & 0x10) >> 3) | ((pixels[1] & 0x01) >> 0)];
-
-					target += 4;
+					output2bpp(pixels[1]);
 				}
-
-				target += 4;
 			break;
 
 			case 4:
-				target[0] = palette_[((pixels[0] & 0xa0) >> 4) | ((pixels[0] & 0x0a) >> 1)];
-				target[1] = palette_[((pixels[0] & 0x50) >> 3) | ((pixels[0] & 0x05) >> 0)];
-
+				output4bpp(pixels[0]);
 				if constexpr (!is_lpixel) {
-					target[2] = palette_[((pixels[1] & 0xa0) >> 4) | ((pixels[1] & 0x0a) >> 1)];
-					target[3] = palette_[((pixels[1] & 0x50) >> 3) | ((pixels[1] & 0x05) >> 0)];
-
-					target += 2;
+					output4bpp(pixels[1]);
 				}
-
-				target += 2;
 			break;
 
 			case 8:
-				target[0] = mapped_colour(pixels[0]);
-
+				output8bpp(pixels[0]);
 				if constexpr (!is_lpixel) {
-					target[1] = mapped_colour(pixels[1]);
-
-					++target;
+					output8bpp(pixels[1]);
 				}
-				++target;
 			break;
 		}
 	}
@@ -590,35 +578,12 @@ template <int bpp, int index_bits> void Nick::output_character(uint16_t *target,
 			case 1: {
 				// This applies ALTIND0 and ALTIND1.
 				const uint16_t *palette = alt_ind_palettes[character >> 6];
-				target[0] = palette[(pixels & 0x80) >> 7];
-				target[1] = palette[(pixels & 0x40) >> 6];
-				target[2] = palette[(pixels & 0x20) >> 5];
-				target[3] = palette[(pixels & 0x10) >> 4];
-				target[4] = palette[(pixels & 0x08) >> 3];
-				target[5] = palette[(pixels & 0x04) >> 2];
-				target[6] = palette[(pixels & 0x02) >> 1];
-				target[7] = palette[(pixels & 0x01) >> 0];
-				target += 8;
+				output1bpp(pixels);
 			} break;
 
-			case 2:
-				target[0] = palette_[((pixels & 0x80) >> 6) | ((pixels & 0x08) >> 3)];
-				target[1] = palette_[((pixels & 0x40) >> 5) | ((pixels & 0x04) >> 2)];
-				target[2] = palette_[((pixels & 0x20) >> 4) | ((pixels & 0x02) >> 1)];
-				target[3] = palette_[((pixels & 0x10) >> 3) | ((pixels & 0x01) >> 0)];
-				target += 4;
-			break;
-
-			case 4:
-				target[0] = palette_[((pixels & 0xa0) >> 4) | ((pixels & 0x0a) >> 1)];
-				target[1] = palette_[((pixels & 0x50) >> 3) | ((pixels & 0x05) >> 0)];
-				target += 2;
-			break;
-
-			case 8:
-				target[0] = mapped_colour(pixels);
-				++target;
-			break;
+			case 2:		output2bpp(pixels);		break;
+			case 4:		output4bpp(pixels);		break;
+			case 8:		output8bpp(pixels);		break;
 		}
 	}
 }
@@ -636,15 +601,11 @@ template <int bpp> void Nick::output_attributed(uint16_t *target, int columns) {
 		const uint16_t palette[2] = {
 			palette_[attributes >> 4], palette_[attributes & 0x0f]
 		};
-
-		target[0] = palette[(pixels & 0x80) >> 7];
-		target[1] = palette[(pixels & 0x40) >> 6];
-		target[2] = palette[(pixels & 0x20) >> 5];
-		target[3] = palette[(pixels & 0x10) >> 4];
-		target[4] = palette[(pixels & 0x08) >> 3];
-		target[5] = palette[(pixels & 0x04) >> 2];
-		target[6] = palette[(pixels & 0x02) >> 1];
-		target[7] = palette[(pixels & 0x01) >> 0];
-		target += 8;
+		output1bpp(pixels);
 	}
 }
+
+#undef output1bpp
+#undef output2bpp
+#undef output4bpp
+#undef output8bpp

From ed734754e512c93acfc208c38a68fd1461c47fef Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 24 Jun 2021 21:04:21 -0400
Subject: [PATCH 075/117] Adds a through route for IMG files.

---
 Analyser/Static/Enterprise/StaticAnalyser.cpp | 34 +++++++++++++++++++
 Analyser/Static/Enterprise/StaticAnalyser.hpp | 27 +++++++++++++++
 Analyser/Static/StaticAnalyser.cpp            |  2 ++
 3 files changed, 63 insertions(+)

diff --git a/Analyser/Static/Enterprise/StaticAnalyser.cpp b/Analyser/Static/Enterprise/StaticAnalyser.cpp
index e69de29bb..7b701b1d9 100644
--- a/Analyser/Static/Enterprise/StaticAnalyser.cpp
+++ b/Analyser/Static/Enterprise/StaticAnalyser.cpp
@@ -0,0 +1,34 @@
+//
+//  StaticAnalyser.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 24/06/2021.
+//  Copyright 2021 Thomas Harte. All rights reserved.
+//
+
+#include "StaticAnalyser.hpp"
+#include "Target.hpp"
+
+Analyser::Static::TargetList Analyser::Static::Enterprise::GetTargets(const Media &media, const std::string &, TargetPlatform::IntType) {
+	// This analyser can comprehend disks only.
+	if(media.disks.empty()) return {};
+
+	// Otherwise, for now: wave it through.
+	Analyser::Static::TargetList targets;
+
+	using Target = Analyser::Static::Enterprise::Target;
+	auto *const target = new Target;
+	target->media = media;
+
+	// Always require a BASIC.
+	target->basic_version = Target::BASICVersion::Any;
+
+	// If this is a single-sided floppy disk, guess the Macintosh 512kb.
+	if(!media.disks.empty()) {
+		target->dos = Target::DOS::EXDOS;
+	}
+
+	targets.push_back(std::unique_ptr<Analyser::Static::Target>(target));
+
+	return targets;
+}
diff --git a/Analyser/Static/Enterprise/StaticAnalyser.hpp b/Analyser/Static/Enterprise/StaticAnalyser.hpp
index e69de29bb..0d7435d0a 100644
--- a/Analyser/Static/Enterprise/StaticAnalyser.hpp
+++ b/Analyser/Static/Enterprise/StaticAnalyser.hpp
@@ -0,0 +1,27 @@
+//
+//  StaticAnalyser.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 24/06/2021.
+//  Copyright 2018 Thomas Harte. All rights reserved.
+//
+
+#ifndef Analyser_Static_Enterprise_StaticAnalyser_hpp
+#define Analyser_Static_Enterprise_StaticAnalyser_hpp
+
+#include "../StaticAnalyser.hpp"
+#include "../../../Storage/TargetPlatforms.hpp"
+#include <string>
+
+namespace Analyser {
+namespace Static {
+namespace Enterprise {
+
+TargetList GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms);
+
+}
+}
+}
+
+
+#endif /* Analyser_Static_Enterprise_StaticAnalyser_hpp */
diff --git a/Analyser/Static/StaticAnalyser.cpp b/Analyser/Static/StaticAnalyser.cpp
index e145e8345..7f88415d2 100644
--- a/Analyser/Static/StaticAnalyser.cpp
+++ b/Analyser/Static/StaticAnalyser.cpp
@@ -23,6 +23,7 @@
 #include "Coleco/StaticAnalyser.hpp"
 #include "Commodore/StaticAnalyser.hpp"
 #include "DiskII/StaticAnalyser.hpp"
+#include "Enterprise/StaticAnalyser.hpp"
 #include "Macintosh/StaticAnalyser.hpp"
 #include "MSX/StaticAnalyser.hpp"
 #include "Oric/StaticAnalyser.hpp"
@@ -257,6 +258,7 @@ TargetList Analyser::Static::GetTargets(const std::string &file_name) {
 	Append(Coleco);
 	Append(Commodore);
 	Append(DiskII);
+	Append(Enterprise);
 	Append(Macintosh);
 	Append(MSX);
 	Append(Oric);

From d1b89392a2ede51d6e44be575136ceb1c4521092 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 24 Jun 2021 22:18:31 -0400
Subject: [PATCH 076/117] Improve exposiiton.

---
 ClockReceiver/ClockReceiver.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ClockReceiver/ClockReceiver.hpp b/ClockReceiver/ClockReceiver.hpp
index 1a3ddfdb9..6867b1898 100644
--- a/ClockReceiver/ClockReceiver.hpp
+++ b/ClockReceiver/ClockReceiver.hpp
@@ -213,7 +213,7 @@ class HalfCycles: public WrappedInt<HalfCycles> {
 
 		/*!
 			Severs from @c this the effect of dividing by @c divisor; @c this will end up with
-			the value of @c this modulo @c divisor and @c divided by @c divisor is returned.
+			the value of @c this modulo @c divisor . @c this divided by @c divisor is returned.
 		*/
 		forceinline Cycles divide_cycles(const Cycles &divisor) {
 			const HalfCycles half_divisor = HalfCycles(divisor);

From c34a548fa0ab39f034d4cd2f399fe21ec68dba2d Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 24 Jun 2021 22:19:50 -0400
Subject: [PATCH 077/117] Ensure character pixel reads can't go out of bounds.

---
 Machines/Enterprise/Nick.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 933376a73..be9bfd0c1 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -562,10 +562,10 @@ template <int bpp, int index_bits> void Nick::output_character(uint16_t *target,
 		const uint8_t character = ram_[line_data_pointer_[0]];
 		++line_data_pointer_[0];
 
-		const uint8_t pixels = ram_[
+		const uint8_t pixels = ram_[(
 			(line_data_pointer_[1] << index_bits) +
 			(character & ((1 << index_bits) - 1))
-		];
+		) & 0xffff];
 
 		// TODO: below looks repetitious of the above, but I've yet to factor in
 		// ALTINDs and [M/L]SBALTs, so I'll correct for factoring when I've done that.

From 1a97cc8a919ba97cb182f9638c21e1f67f76a77e Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 24 Jun 2021 22:21:01 -0400
Subject: [PATCH 078/117] Start making some effort towards audio generation.

---
 Machines/Enterprise/Dave.cpp       | 61 +++++++++++++++++++++++++++++-
 Machines/Enterprise/Dave.hpp       | 30 ++++++++++++++-
 Machines/Enterprise/Enterprise.cpp | 41 +++++++++++++++++---
 3 files changed, 123 insertions(+), 9 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index b9e3301e1..157d10451 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -10,7 +10,64 @@
 
 using namespace Enterprise;
 
+Dave::Dave(Concurrency::DeferringAsyncTaskQueue &audio_queue) :
+	audio_queue_(audio_queue) {}
+
 void Dave::write(uint16_t address, uint8_t value) {
-	(void)address;
-	(void)value;
+	address &= 0xf;
+	audio_queue_.defer([address, value, this] {
+		switch(address) {
+			case 0:	case 2:	case 4:
+				channels_[address >> 1].reload = (channels_[address >> 1].reload & 0xff00) | value;
+			break;
+			case 1:	case 3:	case 5:
+				channels_[address >> 1].reload = uint16_t((channels_[address >> 1].reload & 0x00ff) | ((value & 0xf) << 4));
+				channels_[address >> 1].distortion = Channel::Distortion((value >> 4)&3);
+				channels_[address >> 1].high_pass = value & 0x40;
+				channels_[address >> 1].ring_modulate = value & 0x80;
+			break;
+
+			// TODO:
+			//
+			//	6:	noise selection.
+			//	7:	sync bits, optional D/As, interrupt rate (albeit some of that shouldn't be on this thread, or possibly even _here_).
+			//	11, 14:	noise amplitude.
+
+			case 8: case 9: case 10:
+				channels_[address - 8].amplitude[0] = value & 0x3f;
+			break;
+			case 11: case 12: case 13:
+				channels_[address - 11].amplitude[1] = value & 0x3f;
+			break;
+		}
+	});
+}
+
+void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
+	// Step 1: divide input clock to 125,000 Hz (?)
+	for(size_t c = 0; c < number_of_samples; c++) {
+#define update_channel(x)								\
+		--channels_[x].count;							\
+		if(!channels_[x].count) {						\
+			channels_[x].output ^= true;				\
+			channels_[x].count = channels_[x].reload;	\
+		}
+
+		update_channel(0);
+		update_channel(1);
+		update_channel(2);
+
+#undef update_channel
+
+		// Dumbest ever first attempt: sum channels.
+		target[(c << 1) + 0] =
+			channels_[0].amplitude[0] * channels_[0].output +
+			channels_[1].amplitude[0] * channels_[1].output +
+			channels_[2].amplitude[0] * channels_[2].output;
+
+		target[(c << 1) + 1] =
+			channels_[0].amplitude[1] * channels_[0].output +
+			channels_[1].amplitude[1] * channels_[1].output +
+			channels_[2].amplitude[1] * channels_[2].output;
+	}
 }
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index 758ce863e..b38f1b79d 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -11,7 +11,9 @@
 
 #include <cstdint>
 
+#include "../../Concurrency/AsyncTaskQueue.hpp"
 #include "../../Numeric/LFSR.hpp"
+#include "../../Outputs/Speaker/Implementation/SampleSource.hpp"
 
 namespace Enterprise {
 
@@ -19,11 +21,37 @@ namespace Enterprise {
 	Models a subset of Dave's behaviour; memory mapping and interrupt status
 	is integrated into the main Enterprise machine.
 */
-class Dave {
+class Dave: public Outputs::Speaker::SampleSource {
 	public:
+		Dave(Concurrency::DeferringAsyncTaskQueue &audio_queue);
+
 		void write(uint16_t address, uint8_t value);
 
+		// MARK: - SampleSource.
+		void set_sample_volume_range([[maybe_unused]] int16_t range) {}
+		static constexpr bool get_is_stereo() { return true; }	// Dave produces stereo sound.
+		void get_samples(std::size_t number_of_samples, int16_t *target);
+
 	private:
+		Concurrency::DeferringAsyncTaskQueue &audio_queue_;
+
+		struct Channel {
+			// User-set values.
+			uint16_t reload = 0;
+			bool high_pass = false;
+			bool ring_modulate = false;
+			enum class Distortion {
+				None,
+				FourBit,
+				FiveBit,
+				SevenBit,
+			} distortion = Distortion::None;
+			uint8_t amplitude[2]{};
+
+			// Current state.
+			uint16_t count = 0;
+			bool output = true;
+		} channels_[3];
 
 		// Various polynomials that contribute to audio generation.
 		Numeric::LFSRv<0xc> poly4_;
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 63e777253..bda4eec55 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -15,11 +15,10 @@
 
 #include "../MachineTypes.hpp"
 
-#include "../../Processors/Z80/Z80.hpp"
-
 #include "../../Analyser/Static/Enterprise/Target.hpp"
-
 #include "../../ClockReceiver/JustInTime.hpp"
+#include "../../Outputs/Speaker/Implementation/LowpassSpeaker.hpp"
+#include "../../Processors/Z80/Z80.hpp"
 
 namespace Enterprise {
 
@@ -65,6 +64,7 @@ namespace Enterprise {
 template <bool has_disk_controller> class ConcreteMachine:
 	public CPU::Z80::BusHandler,
 	public Machine,
+	public MachineTypes::AudioProducer,
 	public MachineTypes::MappedKeyboardMachine,
 	public MachineTypes::MediaTarget,
 	public MachineTypes::ScanProducer,
@@ -85,7 +85,9 @@ template <bool has_disk_controller> class ConcreteMachine:
 		ConcreteMachine([[maybe_unused]] const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
 			min_ram_slot_(min_ram_slot(target)),
 			z80_(*this),
-			nick_(ram_.end() - 65536) {
+			nick_(ram_.end() - 65536),
+			dave_(audio_queue_),
+			speaker_(dave_) {
 			// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
 			set_clock_rate(4'000'000);
 
@@ -207,10 +209,17 @@ template <bool has_disk_controller> class ConcreteMachine:
 			page<2>(0x00);
 			page<3>(0x00);
 
+			// Set up audio.
+			speaker_.set_input_rate(125000.0f);	// TODO: a bigger number, and respect the programmable divider.
+
 			// Pass on any media.
 			insert_media(target.media);
 		}
 
+		~ConcreteMachine() {
+			audio_queue_.flush();
+		}
+
 		// MARK: - Z80::BusHandler.
 		forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
 			using PartialMachineCycle = CPU::Z80::PartialMachineCycle;
@@ -218,7 +227,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 
 			// TODO: possibly apply an access penalty.
 
-
+			time_since_audio_update_ += cycle.length;
 			if(nick_ += cycle.length) {
 				const auto nick = nick_.last_valid();
 				const bool nick_interrupt_line = nick->get_interrupt_line();
@@ -307,6 +316,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 						case 0xa4:	case 0xa5:	case 0xa6:	case 0xa7:
 						case 0xa8:	case 0xa9:	case 0xaa:	case 0xab:
 						case 0xac:	case 0xad:	case 0xae:	case 0xaf:
+							update_audio();
 							dave_.write(address, *cycle.value);
 						break;
 
@@ -314,6 +324,10 @@ template <bool has_disk_controller> class ConcreteMachine:
 							interrupt_mask_ = *cycle.value & 0x55;
 							interrupt_state_ &= ~*cycle.value;
 							update_interrupts();
+
+							if(interrupt_mask_ & 0x45) {
+								printf("Unimplemented interrupts requested: %02x\n", interrupt_mask_ & 0x45);
+							}
 						break;
 						case 0xb5:
 							active_key_line_ = *cycle.value & 0xf;
@@ -349,11 +363,17 @@ template <bool has_disk_controller> class ConcreteMachine:
 
 		void flush() {
 			nick_.flush();
+			update_audio();
+			audio_queue_.perform();
+		}
+
+		inline void update_audio() {
+			speaker_.run_for(audio_queue_, time_since_audio_update_.divide_cycles(Cycles(32)));
 		}
 
 	private:
 		// MARK: - Memory layout
-		std::array<uint8_t, 256 * 1024> ram_;
+		std::array<uint8_t, 256 * 1024> ram_{};
 		std::array<uint8_t, 64 * 1024> exos_;
 		std::array<uint8_t, 16 * 1024> basic_;
 		std::array<uint8_t, 16 * 1024> exdos_rom_;
@@ -408,6 +428,12 @@ template <bool has_disk_controller> class ConcreteMachine:
 			return nick_.last_valid()->get_scaled_scan_status();
 		}
 
+		// MARK: - AudioProducer
+
+		Outputs::Speaker::Speaker *get_speaker() final {
+			return &speaker_;
+		}
+
 		// MARK: - TimedMachine
 		void run_for(const Cycles cycles) override {
 			z80_.run_for(cycles);
@@ -464,7 +490,10 @@ template <bool has_disk_controller> class ConcreteMachine:
 		bool previous_nick_interrupt_line_ = false;
 		// Cf. timing guesses above.
 
+		Concurrency::DeferringAsyncTaskQueue audio_queue_;
 		Dave dave_;
+		Outputs::Speaker::LowpassSpeaker<Dave> speaker_;
+		HalfCycles time_since_audio_update_;
 
 		// MARK: - EXDos card.
 		EXDos exdos_;

From c2d093fa3cd619decf328120f2972af5a1ffb023 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 24 Jun 2021 22:27:02 -0400
Subject: [PATCH 079/117] Respect user volume input.

Basic tones are now present. Neato!
---
 Machines/Enterprise/Dave.cpp | 22 ++++++++++++++++------
 Machines/Enterprise/Dave.hpp |  3 ++-
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 157d10451..a030edb0f 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -43,6 +43,12 @@ void Dave::write(uint16_t address, uint8_t value) {
 	});
 }
 
+void Dave::set_sample_volume_range(int16_t range) {
+	audio_queue_.defer([range, this] {
+		volume_ = range / (63*3);
+	});
+}
+
 void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
 	// Step 1: divide input clock to 125,000 Hz (?)
 	for(size_t c = 0; c < number_of_samples; c++) {
@@ -61,13 +67,17 @@ void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
 
 		// Dumbest ever first attempt: sum channels.
 		target[(c << 1) + 0] =
-			channels_[0].amplitude[0] * channels_[0].output +
-			channels_[1].amplitude[0] * channels_[1].output +
-			channels_[2].amplitude[0] * channels_[2].output;
+			volume_ * (
+				channels_[0].amplitude[0] * channels_[0].output +
+				channels_[1].amplitude[0] * channels_[1].output +
+				channels_[2].amplitude[0] * channels_[2].output
+			);
 
 		target[(c << 1) + 1] =
-			channels_[0].amplitude[1] * channels_[0].output +
-			channels_[1].amplitude[1] * channels_[1].output +
-			channels_[2].amplitude[1] * channels_[2].output;
+			volume_ * (
+				channels_[0].amplitude[1] * channels_[0].output +
+				channels_[1].amplitude[1] * channels_[1].output +
+				channels_[2].amplitude[1] * channels_[2].output
+			);
 	}
 }
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index b38f1b79d..911707431 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -28,7 +28,7 @@ class Dave: public Outputs::Speaker::SampleSource {
 		void write(uint16_t address, uint8_t value);
 
 		// MARK: - SampleSource.
-		void set_sample_volume_range([[maybe_unused]] int16_t range) {}
+		void set_sample_volume_range(int16_t range);
 		static constexpr bool get_is_stereo() { return true; }	// Dave produces stereo sound.
 		void get_samples(std::size_t number_of_samples, int16_t *target);
 
@@ -52,6 +52,7 @@ class Dave: public Outputs::Speaker::SampleSource {
 			uint16_t count = 0;
 			bool output = true;
 		} channels_[3];
+		int16_t volume_ = 0;
 
 		// Various polynomials that contribute to audio generation.
 		Numeric::LFSRv<0xc> poly4_;

From f2336d2efca34078e71fa0bbf72d5e1cf16e14ba Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 26 Jun 2021 23:16:00 -0400
Subject: [PATCH 080/117] I think reloads occur after overflow, not before.

---
 Machines/Enterprise/Dave.cpp                                   | 3 ++-
 .../xcshareddata/xcschemes/Clock Signal.xcscheme               | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index a030edb0f..8d5ef6593 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -53,10 +53,11 @@ void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
 	// Step 1: divide input clock to 125,000 Hz (?)
 	for(size_t c = 0; c < number_of_samples; c++) {
 #define update_channel(x)								\
-		--channels_[x].count;							\
 		if(!channels_[x].count) {						\
 			channels_[x].output ^= true;				\
 			channels_[x].count = channels_[x].reload;	\
+		} else {										\
+			--channels_[x].count;						\
 		}
 
 		update_channel(0);
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme
index 54b355ae8..85c8c1e2c 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme	
@@ -73,6 +73,7 @@
       debugDocumentVersioning = "YES"
       migratedStopOnEveryIssue = "YES"
       debugServiceExtension = "internal"
+      enableGPUShaderValidationMode = "2"
       allowLocationSimulation = "NO">
       <BuildableProductRunnable
          runnableDebuggingMode = "0">

From 90782d3c2748820bd8c6d4400ebf3b557ebe0ad3 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 26 Jun 2021 23:39:37 -0400
Subject: [PATCH 081/117] Corrects for IntType != int.

---
 Numeric/LFSR.hpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Numeric/LFSR.hpp b/Numeric/LFSR.hpp
index 04f4cc2fc..b45eba802 100644
--- a/Numeric/LFSR.hpp
+++ b/Numeric/LFSR.hpp
@@ -69,8 +69,8 @@ template <typename IntType = uint64_t, IntType polynomial = LSFRPolynomial<IntTy
 			determining the bit that was just shifted out.
 		*/
 		IntType next() {
-			const auto result = value_ & 1;
-			value_ = (value_ >> 1) ^ (result * polynomial);
+			const auto result = IntType(value_ & 1);
+			value_ = IntType((value_ >> 1) ^ (result * polynomial));
 			return result;
 		}
 

From f8bb66d2a0c22a363aa233f3ea819b6c492768b7 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 26 Jun 2021 23:39:59 -0400
Subject: [PATCH 082/117] Attempts an essentially-complete implementation of
 tone channels.

---
 Machines/Enterprise/Dave.cpp       | 48 +++++++++++++++++++++---------
 Machines/Enterprise/Dave.hpp       | 17 +++++++----
 Machines/Enterprise/Enterprise.cpp |  6 ++--
 3 files changed, 49 insertions(+), 22 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 8d5ef6593..224764c5b 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -50,15 +50,35 @@ void Dave::set_sample_volume_range(int16_t range) {
 }
 
 void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
-	// Step 1: divide input clock to 125,000 Hz (?)
 	for(size_t c = 0; c < number_of_samples; c++) {
-#define update_channel(x)								\
-		if(!channels_[x].count) {						\
-			channels_[x].output ^= true;				\
-			channels_[x].count = channels_[x].reload;	\
-		} else {										\
-			--channels_[x].count;						\
-		}
+		poly_state_[int(Channel::Distortion::FourBit)] = poly4_.next();
+		poly_state_[int(Channel::Distortion::FiveBit)] = poly5_.next();
+		poly_state_[int(Channel::Distortion::SevenBit)] = poly7_.next();
+
+		// TODO: substitute poly_state_[2] if polynomial substitution is in play.
+
+#define update_channel(x) {									\
+		auto output = channels_[x].output & 1;				\
+		channels_[x].output <<= 1;							\
+		if(!channels_[x].count) {							\
+			channels_[x].count = channels_[x].reload;		\
+															\
+			if(channels_[x].distortion == Channel::Distortion::None)	\
+				output ^= 1;								\
+			else											\
+				output = poly_state_[int(channels_[x].distortion)];	\
+															\
+			if(channels_[x].high_pass && (channels_[(x+1)%3].output&3) == 2) {	\
+				output = 0;									\
+			}												\
+			if(channels_[x].ring_modulate) {				\
+				output = ~(output ^ channels_[(x+2)%3].output) & 1;	\
+			}												\
+		} else {											\
+			--channels_[x].count;							\
+		}													\
+		channels_[x].output |= output;						\
+	}
 
 		update_channel(0);
 		update_channel(1);
@@ -69,16 +89,16 @@ void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
 		// Dumbest ever first attempt: sum channels.
 		target[(c << 1) + 0] =
 			volume_ * (
-				channels_[0].amplitude[0] * channels_[0].output +
-				channels_[1].amplitude[0] * channels_[1].output +
-				channels_[2].amplitude[0] * channels_[2].output
+				channels_[0].amplitude[0] * (channels_[0].output & 1) +
+				channels_[1].amplitude[0] * (channels_[1].output & 1) +
+				channels_[2].amplitude[0] * (channels_[2].output & 1)
 			);
 
 		target[(c << 1) + 1] =
 			volume_ * (
-				channels_[0].amplitude[1] * channels_[0].output +
-				channels_[1].amplitude[1] * channels_[1].output +
-				channels_[2].amplitude[1] * channels_[2].output
+				channels_[0].amplitude[1] * (channels_[0].output & 1) +
+				channels_[1].amplitude[1] * (channels_[1].output & 1) +
+				channels_[2].amplitude[1] * (channels_[2].output & 1)
 			);
 	}
 }
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index 911707431..3d7c3619b 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -41,27 +41,32 @@ class Dave: public Outputs::Speaker::SampleSource {
 			bool high_pass = false;
 			bool ring_modulate = false;
 			enum class Distortion {
-				None,
-				FourBit,
-				FiveBit,
-				SevenBit,
+				None = 0,
+				FourBit = 1,
+				FiveBit = 2,
+				SevenBit = 3,
 			} distortion = Distortion::None;
 			uint8_t amplitude[2]{};
 
 			// Current state.
 			uint16_t count = 0;
-			bool output = true;
+			int output = 0;
 		} channels_[3];
 		int16_t volume_ = 0;
 
-		// Various polynomials that contribute to audio generation.
+		// Polynomials that are always running.
 		Numeric::LFSRv<0xc> poly4_;
 		Numeric::LFSRv<0x14> poly5_;
 		Numeric::LFSRv<0x60> poly7_;
+
+		// The selectable, noise-related polynomial.
 		Numeric::LFSRv<0x110> poly9_;
 		Numeric::LFSRv<0x500> poly11_;
 		Numeric::LFSRv<0x6000> poly15_;
 		Numeric::LFSRv<0x12000> poly17_;
+
+		// Current state of the active polynomials.
+		uint8_t poly_state_[4];
 };
 
 }
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index bda4eec55..34ff7fcb5 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -210,7 +210,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 			page<3>(0x00);
 
 			// Set up audio.
-			speaker_.set_input_rate(125000.0f);	// TODO: a bigger number, and respect the programmable divider.
+			speaker_.set_input_rate(250000.0f);	// TODO: a bigger number, and respect the programmable divider.
 
 			// Pass on any media.
 			insert_media(target.media);
@@ -368,7 +368,9 @@ template <bool has_disk_controller> class ConcreteMachine:
 		}
 
 		inline void update_audio() {
-			speaker_.run_for(audio_queue_, time_since_audio_update_.divide_cycles(Cycles(32)));
+			// TODO: divide by only 8, letting Dave divide itself by a further 2 or 3
+			// as per its own register.
+			speaker_.run_for(audio_queue_, time_since_audio_update_.divide_cycles(Cycles(16)));
 		}
 
 	private:

From fcd267a3f9655d8ba6eb324481dfdf603ed7d1cd Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 26 Jun 2021 23:48:53 -0400
Subject: [PATCH 083/117] Starts implementing noise.

---
 Machines/Enterprise/Dave.cpp | 36 ++++++++++++++++++++++++++----------
 Machines/Enterprise/Dave.hpp | 29 +++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 10 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 224764c5b..d3bffe7c5 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -26,26 +26,36 @@ void Dave::write(uint16_t address, uint8_t value) {
 				channels_[address >> 1].high_pass = value & 0x40;
 				channels_[address >> 1].ring_modulate = value & 0x80;
 			break;
+			case 6:
+				noise_.frequency = Noise::Frequency(value&3);
+				noise_.polynomial = Noise::Polynomial((value >> 2)&3);
+				noise_.swap_polynomial = value & 0x10;
+				noise_.low_pass = value & 0x20;
+				noise_.high_pass = value & 0x40;
+				noise_.ring_modulate = value & 0x80;
+			break;
 
 			// TODO:
 			//
-			//	6:	noise selection.
-			//	7:	sync bits, optional D/As, interrupt rate (albeit some of that shouldn't be on this thread, or possibly even _here_).
-			//	11, 14:	noise amplitude.
+			//	7:	sync bits, optional D/As.
+			//
+			//		(will handle interrupt bits elsewhere)
 
 			case 8: case 9: case 10:
 				channels_[address - 8].amplitude[0] = value & 0x3f;
 			break;
-			case 11: case 12: case 13:
-				channels_[address - 11].amplitude[1] = value & 0x3f;
+			case 12: case 13: case 14:
+				channels_[address - 12].amplitude[1] = value & 0x3f;
 			break;
+			case 11:	noise_.amplitude[0] = value & 0x3f;		break;
+			case 15:	noise_.amplitude[1] = value & 0x3f;		break;
 		}
 	});
 }
 
 void Dave::set_sample_volume_range(int16_t range) {
 	audio_queue_.defer([range, this] {
-		volume_ = range / (63*3);
+		volume_ = range / (63*4);
 	});
 }
 
@@ -54,9 +64,11 @@ void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
 		poly_state_[int(Channel::Distortion::FourBit)] = poly4_.next();
 		poly_state_[int(Channel::Distortion::FiveBit)] = poly5_.next();
 		poly_state_[int(Channel::Distortion::SevenBit)] = poly7_.next();
+		if(noise_.swap_polynomial) {
+			poly_state_[int(Channel::Distortion::SevenBit)] = poly_state_[int(Channel::Distortion::None)];
+		}
 
-		// TODO: substitute poly_state_[2] if polynomial substitution is in play.
-
+		// Update tone channels.
 #define update_channel(x) {									\
 		auto output = channels_[x].output & 1;				\
 		channels_[x].output <<= 1;							\
@@ -86,19 +98,23 @@ void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
 
 #undef update_channel
 
+		// TODO: update noise channel.
+
 		// Dumbest ever first attempt: sum channels.
 		target[(c << 1) + 0] =
 			volume_ * (
 				channels_[0].amplitude[0] * (channels_[0].output & 1) +
 				channels_[1].amplitude[0] * (channels_[1].output & 1) +
-				channels_[2].amplitude[0] * (channels_[2].output & 1)
+				channels_[2].amplitude[0] * (channels_[2].output & 1) +
+				noise_.amplitude[0] * noise_.output
 			);
 
 		target[(c << 1) + 1] =
 			volume_ * (
 				channels_[0].amplitude[1] * (channels_[0].output & 1) +
 				channels_[1].amplitude[1] * (channels_[1].output & 1) +
-				channels_[2].amplitude[1] * (channels_[2].output & 1)
+				channels_[2].amplitude[1] * (channels_[2].output & 1) +
+				noise_.amplitude[1] * noise_.output
 			);
 	}
 }
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index 3d7c3619b..1f52bb2f6 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -35,6 +35,7 @@ class Dave: public Outputs::Speaker::SampleSource {
 	private:
 		Concurrency::DeferringAsyncTaskQueue &audio_queue_;
 
+		// Tone channels.
 		struct Channel {
 			// User-set values.
 			uint16_t reload = 0;
@@ -52,6 +53,34 @@ class Dave: public Outputs::Speaker::SampleSource {
 			uint16_t count = 0;
 			int output = 0;
 		} channels_[3];
+
+		// Noise channel.
+		struct Noise {
+			// User-set values.
+			uint8_t amplitude[2]{};
+			enum class Frequency {
+				DivideByFour,
+				ToneChannel0,
+				ToneChannel1,
+				ToneChannel2,
+			} frequency = Frequency::DivideByFour;
+			enum class Polynomial {
+				SeventeenBit,
+				FifteenBit,
+				ElevenBit,
+				NineBit
+			} polynomial = Polynomial::SeventeenBit;
+			bool swap_polynomial = false;
+			bool low_pass = false;
+			bool high_pass = false;
+			bool ring_modulate = false;
+
+			// Current state.
+			bool output = false;
+			uint16_t count = 0;
+		} noise_;
+
+		// Global volume, per SampleSource obligations.
 		int16_t volume_ = 0;
 
 		// Polynomials that are always running.

From f8b7c596160cd35fdcfec50a7365a737b98087e1 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 26 Jun 2021 23:51:43 -0400
Subject: [PATCH 084/117] Corrects tone frequency.

---
 Machines/Enterprise/Dave.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index d3bffe7c5..ddb4b07c6 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -21,7 +21,7 @@ void Dave::write(uint16_t address, uint8_t value) {
 				channels_[address >> 1].reload = (channels_[address >> 1].reload & 0xff00) | value;
 			break;
 			case 1:	case 3:	case 5:
-				channels_[address >> 1].reload = uint16_t((channels_[address >> 1].reload & 0x00ff) | ((value & 0xf) << 4));
+				channels_[address >> 1].reload = uint16_t((channels_[address >> 1].reload & 0x00ff) | ((value & 0xf) << 8));
 				channels_[address >> 1].distortion = Channel::Distortion((value >> 4)&3);
 				channels_[address >> 1].high_pass = value & 0x40;
 				channels_[address >> 1].ring_modulate = value & 0x80;

From 903e343895eb689fad32af1f024e81e5171d9fab Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 14:06:49 -0400
Subject: [PATCH 085/117] Attempts to complete Dave's audio duties.

---
 Machines/Enterprise/Dave.cpp       | 166 ++++++++++++++++++++---------
 Machines/Enterprise/Dave.hpp       |  16 ++-
 Machines/Enterprise/Enterprise.cpp |   4 +-
 3 files changed, 132 insertions(+), 54 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index ddb4b07c6..87a83afed 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -8,12 +8,12 @@
 
 #include "Dave.hpp"
 
-using namespace Enterprise;
+using namespace Enterprise::Dave;
 
-Dave::Dave(Concurrency::DeferringAsyncTaskQueue &audio_queue) :
+Audio::Audio(Concurrency::DeferringAsyncTaskQueue &audio_queue) :
 	audio_queue_(audio_queue) {}
 
-void Dave::write(uint16_t address, uint8_t value) {
+void Audio::write(uint16_t address, uint8_t value) {
 	address &= 0xf;
 	audio_queue_.defer([address, value, this] {
 		switch(address) {
@@ -35,11 +35,14 @@ void Dave::write(uint16_t address, uint8_t value) {
 				noise_.ring_modulate = value & 0x80;
 			break;
 
-			// TODO:
-			//
-			//	7:	sync bits, optional D/As.
-			//
-			//		(will handle interrupt bits elsewhere)
+			case 7:
+				channels_[0].sync = value & 0x01;
+				channels_[1].sync = value & 0x02;
+				channels_[2].sync = value & 0x04;
+				use_direct_output_[0] = value & 0x08;
+				use_direct_output_[1] = value & 0x10;
+				// Interrupt bits are handled separately.
+			break;
 
 			case 8: case 9: case 10:
 				channels_[address - 8].amplitude[0] = value & 0x3f;
@@ -53,13 +56,43 @@ void Dave::write(uint16_t address, uint8_t value) {
 	});
 }
 
-void Dave::set_sample_volume_range(int16_t range) {
+void Audio::set_sample_volume_range(int16_t range) {
 	audio_queue_.defer([range, this] {
 		volume_ = range / (63*4);
 	});
 }
 
-void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
+void Audio::update_channel(int c) {
+	if(channels_[c].sync) {
+		channels_[c].count = channels_[c].reload;
+		channels_[c].output <<= 1;
+		return;
+	}
+
+	auto output = channels_[c].output & 1;
+	channels_[c].output <<= 1;
+	if(!channels_[c].count) {
+		channels_[c].count = channels_[c].reload;
+
+		if(channels_[c].distortion == Channel::Distortion::None)
+			output ^= 1;
+		else
+			output = poly_state_[int(channels_[c].distortion)];
+
+		if(channels_[c].high_pass && (channels_[(c+1)%3].output&3) == 2) {
+			output = 0;
+		}
+		if(channels_[c].ring_modulate) {
+			output = ~(output ^ channels_[(c+2)%3].output) & 1;
+		}
+	} else {
+		--channels_[c].count;
+	}
+
+	channels_[c].output |= output;
+}
+
+void Audio::get_samples(std::size_t number_of_samples, int16_t *target) {
 	for(size_t c = 0; c < number_of_samples; c++) {
 		poly_state_[int(Channel::Distortion::FourBit)] = poly4_.next();
 		poly_state_[int(Channel::Distortion::FiveBit)] = poly5_.next();
@@ -69,52 +102,89 @@ void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
 		}
 
 		// Update tone channels.
-#define update_channel(x) {									\
-		auto output = channels_[x].output & 1;				\
-		channels_[x].output <<= 1;							\
-		if(!channels_[x].count) {							\
-			channels_[x].count = channels_[x].reload;		\
-															\
-			if(channels_[x].distortion == Channel::Distortion::None)	\
-				output ^= 1;								\
-			else											\
-				output = poly_state_[int(channels_[x].distortion)];	\
-															\
-			if(channels_[x].high_pass && (channels_[(x+1)%3].output&3) == 2) {	\
-				output = 0;									\
-			}												\
-			if(channels_[x].ring_modulate) {				\
-				output = ~(output ^ channels_[(x+2)%3].output) & 1;	\
-			}												\
-		} else {											\
-			--channels_[x].count;							\
-		}													\
-		channels_[x].output |= output;						\
-	}
-
 		update_channel(0);
 		update_channel(1);
 		update_channel(2);
 
-#undef update_channel
+		// Update noise channel.
 
-		// TODO: update noise channel.
+		// Step 1: decide whether there is a tick to apply.
+		bool noise_tick = false;
+		if(noise_.frequency == Noise::Frequency::DivideByFour) {
+			if(!noise_.count) {
+				noise_tick = true;
+				noise_.count = 3;
+			} else {
+				--noise_.count;
+			}
+		} else {
+			noise_tick = (channels_[int(noise_.frequency) - 1].output&3) == 2;
+		}
 
-		// Dumbest ever first attempt: sum channels.
+		// Step 2: tick if necessary.
+		if(noise_tick) {
+			switch(noise_.polynomial) {
+				case Noise::Polynomial::SeventeenBit:
+					poly_state_[int(Channel::Distortion::None)] = uint8_t(poly17_.next());
+				break;
+				case Noise::Polynomial::FifteenBit:
+					poly_state_[int(Channel::Distortion::None)] = uint8_t(poly15_.next());
+				break;
+				case Noise::Polynomial::ElevenBit:
+					poly_state_[int(Channel::Distortion::None)] = uint8_t(poly11_.next());
+				break;
+				case Noise::Polynomial::NineBit:
+					poly_state_[int(Channel::Distortion::None)] = uint8_t(poly9_.next());
+				break;
+			}
+
+			noise_.output <<= 1;
+			noise_.output |= poly_state_[int(Channel::Distortion::None)];
+
+			// Low pass: sample channel 2 on downward transitions of the prima facie output.
+			if(noise_.low_pass) {
+				if((noise_.output & 3) == 2) {
+					noise_.output = (noise_.output & ~1) | (channels_[2].output & 1);
+				} else {
+					noise_.output = (noise_.output & ~1) | (noise_.output & 1);
+				}
+			}
+		}
+
+		// Apply noise high-pass at the rate of the tone channels.
+		if(noise_.high_pass && (channels_[0].output & 3) == 2) {
+			noise_.output &= ~1;
+		}
+
+		// Update noise ring modulation, if any.
+		if(noise_.ring_modulate) {
+			noise_.final_output = !((noise_.output ^ channels_[1].output) & 1);
+		} else {
+			noise_.final_output = noise_.output & 1;
+		}
+
+		// I'm unclear on the details of the time division multiplexing so,
+		// for now, just sum the outputs.
 		target[(c << 1) + 0] =
-			volume_ * (
-				channels_[0].amplitude[0] * (channels_[0].output & 1) +
-				channels_[1].amplitude[0] * (channels_[1].output & 1) +
-				channels_[2].amplitude[0] * (channels_[2].output & 1) +
-				noise_.amplitude[0] * noise_.output
-			);
+			volume_ *
+				(use_direct_output_[0] ?
+					channels_[0].amplitude[0]
+					: (
+						channels_[0].amplitude[0] * (channels_[0].output & 1) +
+						channels_[1].amplitude[0] * (channels_[1].output & 1) +
+						channels_[2].amplitude[0] * (channels_[2].output & 1) +
+						noise_.amplitude[0] * noise_.final_output
+				));
 
 		target[(c << 1) + 1] =
-			volume_ * (
-				channels_[0].amplitude[1] * (channels_[0].output & 1) +
-				channels_[1].amplitude[1] * (channels_[1].output & 1) +
-				channels_[2].amplitude[1] * (channels_[2].output & 1) +
-				noise_.amplitude[1] * noise_.output
-			);
+			volume_ *
+				(use_direct_output_[1] ?
+					channels_[0].amplitude[1]
+					: (
+						channels_[0].amplitude[1] * (channels_[0].output & 1) +
+						channels_[1].amplitude[1] * (channels_[1].output & 1) +
+						channels_[2].amplitude[1] * (channels_[2].output & 1) +
+						noise_.amplitude[1] * noise_.final_output
+				));
 	}
 }
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index 1f52bb2f6..6f9b5fdfa 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -16,14 +16,15 @@
 #include "../../Outputs/Speaker/Implementation/SampleSource.hpp"
 
 namespace Enterprise {
+namespace Dave {
 
 /*!
 	Models a subset of Dave's behaviour; memory mapping and interrupt status
 	is integrated into the main Enterprise machine.
 */
-class Dave: public Outputs::Speaker::SampleSource {
+class Audio: public Outputs::Speaker::SampleSource {
 	public:
-		Dave(Concurrency::DeferringAsyncTaskQueue &audio_queue);
+		Audio(Concurrency::DeferringAsyncTaskQueue &audio_queue);
 
 		void write(uint16_t address, uint8_t value);
 
@@ -48,11 +49,13 @@ class Dave: public Outputs::Speaker::SampleSource {
 				SevenBit = 3,
 			} distortion = Distortion::None;
 			uint8_t amplitude[2]{};
+			bool sync = false;
 
 			// Current state.
 			uint16_t count = 0;
 			int output = 0;
 		} channels_[3];
+		void update_channel(int);
 
 		// Noise channel.
 		struct Noise {
@@ -76,9 +79,13 @@ class Dave: public Outputs::Speaker::SampleSource {
 			bool ring_modulate = false;
 
 			// Current state.
-			bool output = false;
-			uint16_t count = 0;
+			int count = 0;
+			int output = false;
+			bool final_output = false;
 		} noise_;
+		void update_noise();
+
+		bool use_direct_output_[2]{};
 
 		// Global volume, per SampleSource obligations.
 		int16_t volume_ = 0;
@@ -98,6 +105,7 @@ class Dave: public Outputs::Speaker::SampleSource {
 		uint8_t poly_state_[4];
 };
 
+}
 }
 
 #endif /* Dave_hpp */
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 34ff7fcb5..4673387d9 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -493,8 +493,8 @@ template <bool has_disk_controller> class ConcreteMachine:
 		// Cf. timing guesses above.
 
 		Concurrency::DeferringAsyncTaskQueue audio_queue_;
-		Dave dave_;
-		Outputs::Speaker::LowpassSpeaker<Dave> speaker_;
+		Dave::Audio dave_;
+		Outputs::Speaker::LowpassSpeaker<Dave::Audio> speaker_;
 		HalfCycles time_since_audio_update_;
 
 		// MARK: - EXDos card.

From 895d98e266ac7b30b9eee195d27cb4db606d06a6 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 16:11:22 -0400
Subject: [PATCH 086/117] Implements out-of-video-area pauses.

---
 Machines/Enterprise/Enterprise.cpp | 47 +++++++++++++++++++++++++++---
 1 file changed, 43 insertions(+), 4 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 4673387d9..418c06de2 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -226,9 +226,31 @@ template <bool has_disk_controller> class ConcreteMachine:
 			const uint16_t address = cycle.address ? *cycle.address : 0x0000;
 
 			// TODO: possibly apply an access penalty.
+			HalfCycles penalty;
+			if(is_video_[address >> 14]) {
+				// TODO.
+			} else {
+				switch(cycle.operation) {
+					default: break;
 
-			time_since_audio_update_ += cycle.length;
-			if(nick_ += cycle.length) {
+					case CPU::Z80::PartialMachineCycle::ReadStart:
+					case CPU::Z80::PartialMachineCycle::WriteStart:
+						if(wait_mode_ == WaitMode::OnAllAccesses) {
+							penalty = HalfCycles(2);
+						}
+					break;
+
+					case CPU::Z80::PartialMachineCycle::ReadOpcodeStart:
+						if(wait_mode_ != WaitMode::None) {
+							penalty = HalfCycles(2);
+						}
+					break;
+				}
+			}
+
+			const HalfCycles full_length = cycle.length + penalty;
+			time_since_audio_update_ += full_length;
+			if(nick_ += full_length) {
 				const auto nick = nick_.last_valid();
 				const bool nick_interrupt_line = nick->get_interrupt_line();
 				if(nick_interrupt_line && !previous_nick_interrupt_line_) {
@@ -239,7 +261,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 
 			// The WD/etc runs at a nominal 8Mhz.
 			if constexpr (has_disk_controller) {
-				exdos_.run_for(Cycles(cycle.length.as_integral()));
+				exdos_.run_for(Cycles(full_length.as_integral()));
 			}
 
 			switch(cycle.operation) {
@@ -338,6 +360,11 @@ template <bool has_disk_controller> class ConcreteMachine:
 						break;
 						case 0xbf:
 							printf("TODO: Dave sysconfig %02x\n", *cycle.value);
+							switch((*cycle.value >> 2)&3) {
+								default:	wait_mode_ = WaitMode::None;			break;
+								case 0:		wait_mode_ = WaitMode::OnAllAccesses;	break;
+								case 1:		wait_mode_ = WaitMode::OnM1;			break;
+							}
 						break;
 					}
 				break;
@@ -358,7 +385,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 				break;
 			}
 
-			return HalfCycles(0);
+			return penalty;
 		}
 
 		void flush() {
@@ -392,6 +419,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 #define Map(location, source)												\
 	if(offset >= location && offset < location + source.size() / 0x4000) {	\
 		page<slot>(&source[(offset - location) * 0x4000], nullptr);			\
+		is_video_[slot] = false;											\
 		return;																\
 	}
 
@@ -409,6 +437,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 			if(offset >= min_ram_slot_) {
 				const auto ram_floor = 4194304 - ram_.size();
 				const size_t address = offset * 0x4000 - ram_floor;
+				is_video_[slot] = offset >= 0xfc;	// TODO: this hard-codes a 64kb video assumption.
 				page<slot>(&ram_[address], &ram_[address]);
 				return;
 			}
@@ -421,6 +450,16 @@ template <bool has_disk_controller> class ConcreteMachine:
 			write_pointers_[slot] = write ? write - (slot * 0x4000) : nullptr;
 		}
 
+		// MARK: - Memory Timing
+
+		// The wait mode affects all memory accesses _outside of the video area_.
+		enum class WaitMode {
+			None,
+			OnM1,
+			OnAllAccesses
+		} wait_mode_ = WaitMode::None;
+		bool is_video_[4]{};
+
 		// MARK: - ScanProducer
 		void set_scan_target(Outputs::Display::ScanTarget *scan_target) override {
 			nick_.last_valid()->set_scan_target(scan_target);

From 10bf6744aaef4dc873ad12c4ff0b770e6eb8ceb4 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 16:26:55 -0400
Subject: [PATCH 087/117] Correct typo.

---
 Machines/Apple/Macintosh/Keyboard.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Machines/Apple/Macintosh/Keyboard.hpp b/Machines/Apple/Macintosh/Keyboard.hpp
index e89840bdc..d69af1f56 100644
--- a/Machines/Apple/Macintosh/Keyboard.hpp
+++ b/Machines/Apple/Macintosh/Keyboard.hpp
@@ -271,7 +271,7 @@ class Keyboard {
 		/// so this may not be valid prior to Mode::PerformingCommand.
 		int command_ = 0;
 		/// Populated during PerformingCommand as the response to the most-recently-received command, this
-		/// is then shifted out to teh host computer. So it is guaranteed valid at the beginning of Mode::SendingResponse,
+		/// is then shifted out to the host computer. So it is guaranteed valid at the beginning of Mode::SendingResponse,
 		/// but not afterwards.
 		int response_ = 0;
 

From bdcab447f98121d040d9911568c8ae67a2836936 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 16:27:26 -0400
Subject: [PATCH 088/117] Add a further accessor.

---
 Processors/Z80/Z80.hpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Processors/Z80/Z80.hpp b/Processors/Z80/Z80.hpp
index fd8eaad5d..caa0ae2f8 100644
--- a/Processors/Z80/Z80.hpp
+++ b/Processors/Z80/Z80.hpp
@@ -145,6 +145,12 @@ struct PartialMachineCycle {
 	forceinline bool is_wait() const {
 		return operation >= Operation::ReadOpcodeWait && operation <= Operation::InterruptWait;
 	}
+	/*!
+		@returns @c true if this partial machine cycle is a memory access; @c false otherwise.
+	*/
+	forceinline bool is_memory_access() const {
+		return operation <= Operation::Write;
+	}
 
 	enum Line {
 		CLK = 1 << 0,

From 1ea034310ad48ee94f387e507339602bc9955591 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 16:28:01 -0400
Subject: [PATCH 089/117] Edge up very close to video waits.

I just need to implement back conversions that include marginal phase over in the JustInTimeActor.
---
 Machines/Enterprise/Enterprise.cpp | 46 +++++++++++++++++++-----------
 Machines/Enterprise/Nick.cpp       | 14 +++++++--
 Machines/Enterprise/Nick.hpp       |  3 +-
 3 files changed, 43 insertions(+), 20 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 418c06de2..a01608751 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -225,26 +225,38 @@ template <bool has_disk_controller> class ConcreteMachine:
 			using PartialMachineCycle = CPU::Z80::PartialMachineCycle;
 			const uint16_t address = cycle.address ? *cycle.address : 0x0000;
 
-			// TODO: possibly apply an access penalty.
+			// Calculate an access penalty, if applicable.
 			HalfCycles penalty;
-			if(is_video_[address >> 14]) {
-				// TODO.
-			} else {
-				switch(cycle.operation) {
-					default: break;
+			switch(cycle.operation) {
+				default: break;
 
-					case CPU::Z80::PartialMachineCycle::ReadStart:
-					case CPU::Z80::PartialMachineCycle::WriteStart:
-						if(wait_mode_ == WaitMode::OnAllAccesses) {
-							penalty = HalfCycles(2);
-						}
-					break;
+				// For non-video pauses, insert during the initial part of the bus cycle.
+				case CPU::Z80::PartialMachineCycle::ReadStart:
+				case CPU::Z80::PartialMachineCycle::WriteStart:
+					if(!is_video_[address >> 14] && wait_mode_ == WaitMode::OnAllAccesses) {
+						penalty = HalfCycles(2);
+					}
+				break;
+				case CPU::Z80::PartialMachineCycle::ReadOpcodeStart:
+					if(!is_video_[address >> 14] && wait_mode_ != WaitMode::None) {
+						penalty = HalfCycles(2);
+					}
+				break;
 
-					case CPU::Z80::PartialMachineCycle::ReadOpcodeStart:
-						if(wait_mode_ != WaitMode::None) {
-							penalty = HalfCycles(2);
-						}
-					break;
+				// Video pauses: insert right at the end of the bus cycle.
+				case CPU::Z80::PartialMachineCycle::ReadOpcode:
+				case CPU::Z80::PartialMachineCycle::Read:
+				case CPU::Z80::PartialMachineCycle::Write:
+					if(is_video_[address >> 14]) {
+						// TODO.
+					}
+				break;
+
+				case CPU::Z80::PartialMachineCycle::Input:
+				case CPU::Z80::PartialMachineCycle::Output: {
+					if((address & 0xf0) == 0x80) {
+						// TODO.
+					}
 				}
 			}
 
diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index be9bfd0c1..139285e49 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -92,7 +92,17 @@ uint8_t Nick::read([[maybe_unused]] uint16_t address) {
 	return 0xff;
 }
 
-//int c;
+Cycles Nick::get_time_until_z80_slot() const {
+	// Place Z80 accesses as the first six cycles in each sixteen-cycle window.
+	// That models video accesses as being the final ten. Which has the net effect
+	// of responding to the line parameter table interrupt flag as soon as it's
+	// loaded.
+
+	// i.e. 0 -> 0, 1 -> 15 ... 15 -> 1.
+	return Cycles(
+		15 ^ ((horizontal_counter_ + 15) & 15)
+	);
+}
 
 void Nick::run_for(Cycles duration) {
 	constexpr int line_length = 912;
@@ -455,7 +465,7 @@ void Nick::set_output_type(OutputType type, bool force_flush) {
 
 // MARK: - Sequence points.
 
-Cycles Nick::get_next_sequence_point() {
+Cycles Nick::get_next_sequence_point() const {
 	// TODO: the below is incorrect; unit test and correct.
 	// Changing to e.g. Cycles(1) reveals the relevant discrepancy.
 //	return Cycles(1);
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 31911e90d..75b220c12 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -23,11 +23,12 @@ class Nick {
 		uint8_t read(uint16_t address);
 
 		void run_for(Cycles);
+		Cycles get_time_until_z80_slot() const;
 
 		void set_scan_target(Outputs::Display::ScanTarget *scan_target);
 		Outputs::Display::ScanStatus get_scaled_scan_status() const;
 
-		Cycles get_next_sequence_point();
+		Cycles get_next_sequence_point() const;
 
 		/*!
 			@returns The current state of the interrupt line — @c true for active;

From f2d7b9f6a91d412d77e352a85eaf90893e426e00 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 17:13:07 -0400
Subject: [PATCH 090/117] Apply a crop, allow time until Z80 slot to be a
 future-based query.

---
 Machines/Enterprise/Nick.cpp | 7 +++++--
 Machines/Enterprise/Nick.hpp | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 139285e49..69138eede 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -52,6 +52,9 @@ Nick::Nick(const uint8_t *ram) :
 
 	// Just use RGB for now.
 	crt_.set_display_type(Outputs::Display::DisplayType::RGB);
+
+	// Crop to the centre 90% of the display.
+	crt_.set_visible_area(Outputs::Display::Rect(0.05f, 0.05f, 0.9f, 0.9f));
 }
 
 void Nick::write(uint16_t address, uint8_t value) {
@@ -92,7 +95,7 @@ uint8_t Nick::read([[maybe_unused]] uint16_t address) {
 	return 0xff;
 }
 
-Cycles Nick::get_time_until_z80_slot() const {
+Cycles Nick::get_time_until_z80_slot(Cycles after_period) const {
 	// Place Z80 accesses as the first six cycles in each sixteen-cycle window.
 	// That models video accesses as being the final ten. Which has the net effect
 	// of responding to the line parameter table interrupt flag as soon as it's
@@ -100,7 +103,7 @@ Cycles Nick::get_time_until_z80_slot() const {
 
 	// i.e. 0 -> 0, 1 -> 15 ... 15 -> 1.
 	return Cycles(
-		15 ^ ((horizontal_counter_ + 15) & 15)
+		15 ^ ((horizontal_counter_ + 15 + after_period.as<int>()) & 15)
 	);
 }
 
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index 75b220c12..d620d21a8 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -23,7 +23,7 @@ class Nick {
 		uint8_t read(uint16_t address);
 
 		void run_for(Cycles);
-		Cycles get_time_until_z80_slot() const;
+		Cycles get_time_until_z80_slot(Cycles after_period) const;
 
 		void set_scan_target(Outputs::Display::ScanTarget *scan_target);
 		Outputs::Display::ScanStatus get_scaled_scan_status() const;

From 81e9ba5608c5942730ddfa9e2d3972e7ca5e3935 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 17:24:21 -0400
Subject: [PATCH 091/117] This is correct from the Enterprise's side of things,
 I think.

I just need to complete the missing part of JustInTimeActor. After I do some empirical testing of this.
---
 ClockReceiver/JustInTime.hpp       | 17 ++++++++++-
 Machines/Enterprise/Enterprise.cpp | 45 ++++++++++++++++++++++--------
 2 files changed, 49 insertions(+), 13 deletions(-)

diff --git a/ClockReceiver/JustInTime.hpp b/ClockReceiver/JustInTime.hpp
index 4f7c02018..2fa08254b 100644
--- a/ClockReceiver/JustInTime.hpp
+++ b/ClockReceiver/JustInTime.hpp
@@ -145,13 +145,21 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
 
 		/// @returns the amount of time since the object was last flushed, in the target time scale.
 		[[nodiscard]] forceinline TargetTimeScale time_since_flush() const {
-			// TODO: does this handle conversions properly where TargetTimeScale != LocalTimeScale?
 			if constexpr (divider == 1) {
 				return time_since_update_;
 			}
 			return TargetTimeScale(time_since_update_.as_integral() / divider);
 		}
 
+		/// @returns the amount of time since the object was last flushed, plus the local time scale @c offset,
+		/// converted to the target time scale.
+		[[nodiscard]] forceinline TargetTimeScale time_since_flush(LocalTimeScale offset) const {
+			if constexpr (divider == 1) {
+				return time_since_update_ + offset;
+			}
+			return TargetTimeScale((time_since_update_ + offset).as_integral() / divider);
+		}
+
 		/// Flushes all accumulated time.
 		///
 		/// This does not affect this actor's record of when the next sequence point will occur.
@@ -196,6 +204,13 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
 			return rhs >= time_until_event_;
 		}
 
+		/// Indicates the amount of time, in the local time scale, until the first local slot that falls wholly
+		/// after the amount of time provided in the target time scale.
+		[[nodiscard]] forceinline LocalTimeScale back_map(TargetTimeScale time) const {
+			// TODO.
+			return LocalTimeScale(0);
+		}
+
 		/// Updates this template's record of the next sequence point.
 		void update_sequence_point() {
 			if constexpr (has_sequence_points<T>::value) {
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index a01608751..8649ce36f 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -221,6 +221,17 @@ template <bool has_disk_controller> class ConcreteMachine:
 		}
 
 		// MARK: - Z80::BusHandler.
+		forceinline void advance_nick(HalfCycles duration) {
+			if(nick_ += duration) {
+				const auto nick = nick_.last_valid();
+				const bool nick_interrupt_line = nick->get_interrupt_line();
+				if(nick_interrupt_line && !previous_nick_interrupt_line_) {
+					set_interrupt(Interrupt::Nick, nick_.last_sequence_point_overrun());
+				}
+				previous_nick_interrupt_line_ = nick_interrupt_line;
+			}
+		}
+
 		forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
 			using PartialMachineCycle = CPU::Z80::PartialMachineCycle;
 			const uint16_t address = cycle.address ? *cycle.address : 0x0000;
@@ -240,36 +251,46 @@ template <bool has_disk_controller> class ConcreteMachine:
 				case CPU::Z80::PartialMachineCycle::ReadOpcodeStart:
 					if(!is_video_[address >> 14] && wait_mode_ != WaitMode::None) {
 						penalty = HalfCycles(2);
+					} else {
+						// Query Nick for the amount of delay that would occur with one cycle left
+						// in this read opcode.
+						const auto delay = nick_.last_valid()->get_time_until_z80_slot(nick_.time_since_flush(HalfCycles(2)));
+						penalty = nick_.back_map(delay);
 					}
 				break;
 
 				// Video pauses: insert right at the end of the bus cycle.
-				case CPU::Z80::PartialMachineCycle::ReadOpcode:
-				case CPU::Z80::PartialMachineCycle::Read:
 				case CPU::Z80::PartialMachineCycle::Write:
+					// Ensure all video that should have been collected prior to
+					// this write has been.
 					if(is_video_[address >> 14]) {
-						// TODO.
+						nick_.flush();
+					}
+					[[fallthrough]];
+
+				case CPU::Z80::PartialMachineCycle::Read:
+					if(is_video_[address >> 14]) {
+						// Get delay, in Nick cycles, for a Z80 access that occurs in 0.5
+						// cycles from now (i.e. with one cycle left to run).
+						const auto delay = nick_.last_valid()->get_time_until_z80_slot(nick_.time_since_flush(HalfCycles(1)));
+						penalty = nick_.back_map(delay);
 					}
 				break;
 
 				case CPU::Z80::PartialMachineCycle::Input:
 				case CPU::Z80::PartialMachineCycle::Output: {
 					if((address & 0xf0) == 0x80) {
-						// TODO.
+						// Get delay, in Nick cycles, for a Z80 access that occurs in 0.5
+						// cycles from now (i.e. with one cycle left to run).
+						const auto delay = nick_.last_valid()->get_time_until_z80_slot(nick_.time_since_flush(HalfCycles(1)));
+						penalty = nick_.back_map(delay);
 					}
 				}
 			}
 
 			const HalfCycles full_length = cycle.length + penalty;
 			time_since_audio_update_ += full_length;
-			if(nick_ += full_length) {
-				const auto nick = nick_.last_valid();
-				const bool nick_interrupt_line = nick->get_interrupt_line();
-				if(nick_interrupt_line && !previous_nick_interrupt_line_) {
-					set_interrupt(Interrupt::Nick, nick_.last_sequence_point_overrun());
-				}
-				previous_nick_interrupt_line_ = nick_interrupt_line;
-			}
+			advance_nick(full_length);
 
 			// The WD/etc runs at a nominal 8Mhz.
 			if constexpr (has_disk_controller) {

From be19fa9dde184af4aa456128ed7e0a52938130aa Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 17:30:09 -0400
Subject: [PATCH 092/117] This mapping needs to know where it will occur.

---
 ClockReceiver/JustInTime.hpp       |  4 ++--
 Machines/Enterprise/Enterprise.cpp | 27 +++++++++++++++++++++------
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/ClockReceiver/JustInTime.hpp b/ClockReceiver/JustInTime.hpp
index 2fa08254b..c87da1976 100644
--- a/ClockReceiver/JustInTime.hpp
+++ b/ClockReceiver/JustInTime.hpp
@@ -205,8 +205,8 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
 		}
 
 		/// Indicates the amount of time, in the local time scale, until the first local slot that falls wholly
-		/// after the amount of time provided in the target time scale.
-		[[nodiscard]] forceinline LocalTimeScale back_map(TargetTimeScale time) const {
+		/// after @c duration, if that delay were to occur in @c offset units of time from now.
+		[[nodiscard]] forceinline LocalTimeScale back_map(TargetTimeScale duration, TargetTimeScale offset) const {
 			// TODO.
 			return LocalTimeScale(0);
 		}
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 8649ce36f..806eb0ffe 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -237,6 +237,18 @@ template <bool has_disk_controller> class ConcreteMachine:
 			const uint16_t address = cycle.address ? *cycle.address : 0x0000;
 
 			// Calculate an access penalty, if applicable.
+			//
+			// Rule applied here, which is slightly inferred:
+			//
+			//	Non-video reads and writes are delayed by exactly a cycle or not delayed at all,
+			//	depending on the programmer's configuration of Dave.
+			//
+			//	Video reads and writes, and Nick port accesses, are delayed so that the last
+			//	clock cycle of the machine cycle falls wholly inside the designated Z80 access
+			//	window, per Nick.
+			//
+			// The switch statement below just attempts to implement that logic.
+			//
 			HalfCycles penalty;
 			switch(cycle.operation) {
 				default: break;
@@ -254,8 +266,9 @@ template <bool has_disk_controller> class ConcreteMachine:
 					} else {
 						// Query Nick for the amount of delay that would occur with one cycle left
 						// in this read opcode.
-						const auto delay = nick_.last_valid()->get_time_until_z80_slot(nick_.time_since_flush(HalfCycles(2)));
-						penalty = nick_.back_map(delay);
+						const auto delay_time = nick_.time_since_flush(HalfCycles(2));
+						const auto delay = nick_.last_valid()->get_time_until_z80_slot(delay_time);
+						penalty = nick_.back_map(delay, delay_time);
 					}
 				break;
 
@@ -272,8 +285,9 @@ template <bool has_disk_controller> class ConcreteMachine:
 					if(is_video_[address >> 14]) {
 						// Get delay, in Nick cycles, for a Z80 access that occurs in 0.5
 						// cycles from now (i.e. with one cycle left to run).
-						const auto delay = nick_.last_valid()->get_time_until_z80_slot(nick_.time_since_flush(HalfCycles(1)));
-						penalty = nick_.back_map(delay);
+						const auto delay_time = nick_.time_since_flush(HalfCycles(1));
+						const auto delay = nick_.last_valid()->get_time_until_z80_slot(delay_time);
+						penalty = nick_.back_map(delay, delay_time);
 					}
 				break;
 
@@ -282,8 +296,9 @@ template <bool has_disk_controller> class ConcreteMachine:
 					if((address & 0xf0) == 0x80) {
 						// Get delay, in Nick cycles, for a Z80 access that occurs in 0.5
 						// cycles from now (i.e. with one cycle left to run).
-						const auto delay = nick_.last_valid()->get_time_until_z80_slot(nick_.time_since_flush(HalfCycles(1)));
-						penalty = nick_.back_map(delay);
+						const auto delay_time = nick_.time_since_flush(HalfCycles(1));
+						const auto delay = nick_.last_valid()->get_time_until_z80_slot(delay_time);
+						penalty = nick_.back_map(delay, delay_time);
 					}
 				}
 			}

From 95c906f03dd8fc33b47502739cbe4ce2cb1220dc Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 17:36:25 -0400
Subject: [PATCH 093/117] Takes a serious shot at `back_map`.

---
 ClockReceiver/JustInTime.hpp | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/ClockReceiver/JustInTime.hpp b/ClockReceiver/JustInTime.hpp
index c87da1976..32208e5f0 100644
--- a/ClockReceiver/JustInTime.hpp
+++ b/ClockReceiver/JustInTime.hpp
@@ -207,8 +207,22 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
 		/// Indicates the amount of time, in the local time scale, until the first local slot that falls wholly
 		/// after @c duration, if that delay were to occur in @c offset units of time from now.
 		[[nodiscard]] forceinline LocalTimeScale back_map(TargetTimeScale duration, TargetTimeScale offset) const {
-			// TODO.
-			return LocalTimeScale(0);
+			// A 1:1 mapping is easy.
+			if constexpr (multiplier == 1 && divider == 1) {
+				return duration;
+			}
+
+			// Work out when this query is placed, and the time to which it relates
+			const auto base = time_since_update_ + offset * divider;
+			const auto target = base + duration * divider;
+
+			// Figure out the number of whole input steps that is required to get
+			// past target, and subtract the number of whole input steps necessary
+			// to get to base.
+			const auto steps_to_base = base.as_integral() / divider;
+			const auto steps_to_target = (target.as_integral() + divider - 1) / divider;
+
+			return LocalTimeScale(steps_to_target - steps_to_base);
 		}
 
 		/// Updates this template's record of the next sequence point.

From b698056f78d049a5240aa22563fd3a9b23107397 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 17:39:13 -0400
Subject: [PATCH 094/117] Correct divisor.

---
 ClockReceiver/JustInTime.hpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ClockReceiver/JustInTime.hpp b/ClockReceiver/JustInTime.hpp
index 32208e5f0..1734d5846 100644
--- a/ClockReceiver/JustInTime.hpp
+++ b/ClockReceiver/JustInTime.hpp
@@ -219,8 +219,8 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
 			// Figure out the number of whole input steps that is required to get
 			// past target, and subtract the number of whole input steps necessary
 			// to get to base.
-			const auto steps_to_base = base.as_integral() / divider;
-			const auto steps_to_target = (target.as_integral() + divider - 1) / divider;
+			const auto steps_to_base = base.as_integral() / multiplier;
+			const auto steps_to_target = (target.as_integral() + divider - 1) / multiplier;
 
 			return LocalTimeScale(steps_to_target - steps_to_base);
 		}

From 2f53b105bb6aa4bee8aa12701210b5ed44891d6c Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 21:02:04 -0400
Subject: [PATCH 095/117] The Enterprise is now an Activity::Source; also
 sketches out the owner of Dave's timed interrupt logic.

---
 Machines/Enterprise/Dave.cpp       | 19 ++++++++++++++
 Machines/Enterprise/Dave.hpp       | 28 ++++++++++++++++++--
 Machines/Enterprise/EXDos.cpp      |  6 +++++
 Machines/Enterprise/EXDos.hpp      |  2 ++
 Machines/Enterprise/Enterprise.cpp | 41 +++++++++++++++++++-----------
 5 files changed, 79 insertions(+), 17 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 87a83afed..7d354f98c 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -10,6 +10,8 @@
 
 using namespace Enterprise::Dave;
 
+// MARK: - Audio generator
+
 Audio::Audio(Concurrency::DeferringAsyncTaskQueue &audio_queue) :
 	audio_queue_(audio_queue) {}
 
@@ -188,3 +190,20 @@ void Audio::get_samples(std::size_t number_of_samples, int16_t *target) {
 				));
 	}
 }
+
+// MARK: - Interrupt source
+
+uint8_t TimedInterruptSource::get_new_interrupts() {
+	const uint8_t result = interrupts_;
+	interrupts_ = 0;
+	return result;
+}
+
+void TimedInterruptSource::write(uint16_t address, uint8_t value) {
+	(void)address;
+	(void)value;
+}
+
+void TimedInterruptSource::run_for(Cycles cycles) {
+	(void)cycles;
+}
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index 6f9b5fdfa..3953bc211 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -11,6 +11,7 @@
 
 #include <cstdint>
 
+#include "../../ClockReceiver/ClockReceiver.hpp"
 #include "../../Concurrency/AsyncTaskQueue.hpp"
 #include "../../Numeric/LFSR.hpp"
 #include "../../Outputs/Speaker/Implementation/SampleSource.hpp"
@@ -18,9 +19,14 @@
 namespace Enterprise {
 namespace Dave {
 
+enum class Interrupt: uint8_t {
+	VariableFrequency = 0x02,
+	OneHz = 0x08,
+	Nick = 0x20,
+};
+
 /*!
-	Models a subset of Dave's behaviour; memory mapping and interrupt status
-	is integrated into the main Enterprise machine.
+	Models the audio-production subset of Dave's behaviour.
 */
 class Audio: public Outputs::Speaker::SampleSource {
 	public:
@@ -105,6 +111,24 @@ class Audio: public Outputs::Speaker::SampleSource {
 		uint8_t poly_state_[4];
 };
 
+/*!
+	Provides Dave's timed interrupts — those that are provided at 1 kHz,
+	50 Hz or according to the rate of tone generators 0 or 1, plus the fixed
+	1 Hz interrupt.
+
+*/
+class TimedInterruptSource {
+	public:
+		void write(uint16_t address, uint8_t value);
+
+		uint8_t get_new_interrupts();
+
+		void run_for(Cycles);
+
+	private:
+		uint8_t interrupts_ = 0;
+};
+
 }
 }
 
diff --git a/Machines/Enterprise/EXDos.cpp b/Machines/Enterprise/EXDos.cpp
index ec7673407..015626e2a 100644
--- a/Machines/Enterprise/EXDos.cpp
+++ b/Machines/Enterprise/EXDos.cpp
@@ -70,3 +70,9 @@ void EXDos::set_motor_on(bool on) {
 	// writing state, so plenty of work to do in general here.
 	get_drive().set_motor_on(on);
 }
+
+void EXDos::set_activity_observer(Activity::Observer *observer) {
+	for_all_drives([observer] (Storage::Disk::Drive &drive, size_t index) {
+		drive.set_activity_observer(observer, "Drive " + std::to_string(index+1), true);
+	});
+}
diff --git a/Machines/Enterprise/EXDos.hpp b/Machines/Enterprise/EXDos.hpp
index 42d8f81c1..33553be6a 100644
--- a/Machines/Enterprise/EXDos.hpp
+++ b/Machines/Enterprise/EXDos.hpp
@@ -23,6 +23,8 @@ class EXDos final : public WD::WD1770 {
 		void set_control_register(uint8_t control);
 		uint8_t get_control_register();
 
+		void set_activity_observer(Activity::Observer *observer);
+
 	private:
 		bool disk_did_change_ = false;
 
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 806eb0ffe..d90eb0450 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -62,6 +62,7 @@ namespace Enterprise {
 */
 
 template <bool has_disk_controller> class ConcreteMachine:
+	public Activity::Source,
 	public CPU::Z80::BusHandler,
 	public Machine,
 	public MachineTypes::AudioProducer,
@@ -86,8 +87,8 @@ template <bool has_disk_controller> class ConcreteMachine:
 			min_ram_slot_(min_ram_slot(target)),
 			z80_(*this),
 			nick_(ram_.end() - 65536),
-			dave_(audio_queue_),
-			speaker_(dave_) {
+			dave_audio_(audio_queue_),
+			speaker_(dave_audio_) {
 			// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
 			set_clock_rate(4'000'000);
 
@@ -226,7 +227,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 				const auto nick = nick_.last_valid();
 				const bool nick_interrupt_line = nick->get_interrupt_line();
 				if(nick_interrupt_line && !previous_nick_interrupt_line_) {
-					set_interrupt(Interrupt::Nick, nick_.last_sequence_point_overrun());
+					set_interrupts(uint8_t(Dave::Interrupt::Nick), nick_.last_sequence_point_overrun());
 				}
 				previous_nick_interrupt_line_ = nick_interrupt_line;
 			}
@@ -306,6 +307,9 @@ template <bool has_disk_controller> class ConcreteMachine:
 			const HalfCycles full_length = cycle.length + penalty;
 			time_since_audio_update_ += full_length;
 			advance_nick(full_length);
+			if(dave_timer_ += full_length) {
+				set_interrupts(dave_timer_.last_valid()->get_new_interrupts(), dave_timer_.last_sequence_point_overrun());
+			}
 
 			// The WD/etc runs at a nominal 8Mhz.
 			if constexpr (has_disk_controller) {
@@ -387,7 +391,8 @@ template <bool has_disk_controller> class ConcreteMachine:
 						case 0xa8:	case 0xa9:	case 0xaa:	case 0xab:
 						case 0xac:	case 0xad:	case 0xae:	case 0xaf:
 							update_audio();
-							dave_.write(address, *cycle.value);
+							dave_audio_.write(address, *cycle.value);
+							dave_timer_->write(address, *cycle.value);
 						break;
 
 						case 0xb4:
@@ -442,12 +447,6 @@ template <bool has_disk_controller> class ConcreteMachine:
 			audio_queue_.perform();
 		}
 
-		inline void update_audio() {
-			// TODO: divide by only 8, letting Dave divide itself by a further 2 or 3
-			// as per its own register.
-			speaker_.run_for(audio_queue_, time_since_audio_update_.divide_cycles(Cycles(16)));
-		}
-
 	private:
 		// MARK: - Memory layout
 		std::array<uint8_t, 256 * 1024> ram_{};
@@ -560,12 +559,9 @@ template <bool has_disk_controller> class ConcreteMachine:
 		}
 
 		// MARK: - Interrupts
-		enum class Interrupt: uint8_t {
-			Nick = 0x20
-		};
 
 		uint8_t interrupt_mask_ = 0x00, interrupt_state_ = 0x00;
-		void set_interrupt(Interrupt mask, HalfCycles offset = HalfCycles(0)) {
+		void set_interrupts(uint8_t mask, HalfCycles offset = HalfCycles(0)) {
 			interrupt_state_ |= uint8_t(mask);
 			update_interrupts(offset);
 		}
@@ -580,12 +576,27 @@ template <bool has_disk_controller> class ConcreteMachine:
 		// Cf. timing guesses above.
 
 		Concurrency::DeferringAsyncTaskQueue audio_queue_;
-		Dave::Audio dave_;
+		Dave::Audio dave_audio_;
 		Outputs::Speaker::LowpassSpeaker<Dave::Audio> speaker_;
 		HalfCycles time_since_audio_update_;
 
+		// The following two should both use the same divider.
+		JustInTimeActor<Dave::TimedInterruptSource, HalfCycles, 1, 16> dave_timer_;
+		inline void update_audio() {
+			// TODO: divide by only 8, letting Dave divide itself by a further 2 or 3
+			// as per its own register.
+			speaker_.run_for(audio_queue_, time_since_audio_update_.divide_cycles(Cycles(16)));
+		}
+
 		// MARK: - EXDos card.
 		EXDos exdos_;
+
+		// MARK: - Activity Source
+		void set_activity_observer(Activity::Observer *observer) final {
+			if constexpr (has_disk_controller) {
+				exdos_.set_activity_observer(observer);
+			}
+		}
 };
 
 }

From 5729e6e13a38d22ddfd6375be4f3402656033184 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 21:36:41 -0400
Subject: [PATCH 096/117] Corrects potential JustInTimeActor overflow.

---
 ClockReceiver/JustInTime.hpp | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/ClockReceiver/JustInTime.hpp b/ClockReceiver/JustInTime.hpp
index 1734d5846..e7ff2696e 100644
--- a/ClockReceiver/JustInTime.hpp
+++ b/ClockReceiver/JustInTime.hpp
@@ -228,7 +228,19 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
 		/// Updates this template's record of the next sequence point.
 		void update_sequence_point() {
 			if constexpr (has_sequence_points<T>::value) {
-				time_until_event_ = object_.get_next_sequence_point() * divider;
+				// Keep a fast path where no conversions will be applied; if conversions are
+				// going to be applied then do a direct max -> max translation rather than
+				// allowing the arithmetic to overflow.
+				if constexpr (divider == 1 && std::is_same_v<LocalTimeScale, TargetTimeScale>) {
+					time_until_event_ = object_.get_next_sequence_point();
+				} else {
+					const auto time = object_.get_next_sequence_point();
+					if(time == TargetTimeScale::max()) {
+						time_until_event_ = LocalTimeScale::max();
+					} else {
+						time_until_event_ = time * divider;
+					}
+				}
 				assert(time_until_event_ > LocalTimeScale(0));
 			}
 		}

From 6afee7bb9ba649136591badf3b6db75aa696993e Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 21:36:55 -0400
Subject: [PATCH 097/117] Captures appropriate fields.

No action yet.
---
 Machines/Enterprise/Dave.cpp | 23 +++++++++++++++++++++--
 Machines/Enterprise/Dave.hpp | 14 ++++++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 7d354f98c..3b7ca2ab0 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -200,10 +200,29 @@ uint8_t TimedInterruptSource::get_new_interrupts() {
 }
 
 void TimedInterruptSource::write(uint16_t address, uint8_t value) {
-	(void)address;
-	(void)value;
+	address &= 15;
+	switch(address) {
+		default: break;
+
+		case 0: case 2:
+			channels_[address >> 1].reload = (channels_[address >> 1].reload & 0xff00) | value;
+		break;
+		case 1:	case 3:
+			channels_[address >> 1].reload = uint16_t((channels_[address >> 1].reload & 0x00ff) | ((value & 0xf) << 8));
+		break;
+
+		case 7:
+			channels_[0].sync = value & 0x01;
+			channels_[1].sync = value & 0x02;
+			rate_ = InterruptRate((value >> 5) & 3);
+		break;
+	}
 }
 
 void TimedInterruptSource::run_for(Cycles cycles) {
 	(void)cycles;
 }
+
+Cycles TimedInterruptSource::get_next_sequence_point() const {
+	return Cycles::max();
+}
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index 3953bc211..92b14bafb 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -125,8 +125,22 @@ class TimedInterruptSource {
 
 		void run_for(Cycles);
 
+		Cycles get_next_sequence_point() const;
+
 	private:
 		uint8_t interrupts_ = 0;
+
+		enum class InterruptRate {
+			OnekHz,
+			FiftyHz,
+			ToneGenerator0,
+			ToneGenerator1,
+		} rate_ = InterruptRate::OnekHz;
+
+		struct Channel {
+			uint16_t value, reload;
+			bool sync;
+		} channels_[2];
 };
 
 }

From b5312b9ba00ae20937c3983ea41ae6aacd7c95df Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 21:37:11 -0400
Subject: [PATCH 098/117] get_interrupt_line can be const.

---
 Machines/Enterprise/Nick.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index d620d21a8..eef4f19b0 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -34,7 +34,7 @@ class Nick {
 			@returns The current state of the interrupt line — @c true for active;
 				@c false for inactive.
 		*/
-		inline bool get_interrupt_line() {
+		inline bool get_interrupt_line() const {
 			return interrupt_line_;
 		}
 

From e4a650aaff8188d2470c9e8c7d7c32cb96290a73 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 21:47:21 -0400
Subject: [PATCH 099/117] Implements the 1Hz interrupt.

---
 Machines/Enterprise/Dave.cpp       | 12 ++++++++++--
 Machines/Enterprise/Dave.hpp       |  4 ++++
 Machines/Enterprise/Enterprise.cpp |  4 ++--
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 3b7ca2ab0..d4b447bbf 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -220,9 +220,17 @@ void TimedInterruptSource::write(uint16_t address, uint8_t value) {
 }
 
 void TimedInterruptSource::run_for(Cycles cycles) {
-	(void)cycles;
+	// Update the 1Hz interrupt.
+	one_hz_offset_ -= cycles;
+	if(one_hz_offset_ <= Cycles(0)) {
+		interrupts_ |= uint8_t(Interrupt::OneHz);
+		one_hz_offset_ += clock_rate;
+	}
+
+	// TODO: update the programmable-frequency interrupt.
 }
 
 Cycles TimedInterruptSource::get_next_sequence_point() const {
-	return Cycles::max();
+	// TODO: support the programmable-frequency interrupt.
+	return one_hz_offset_;
 }
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index 92b14bafb..47b3e82df 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -130,6 +130,10 @@ class TimedInterruptSource {
 	private:
 		uint8_t interrupts_ = 0;
 
+		static constexpr Cycles clock_rate{250000};
+
+		Cycles one_hz_offset_ = clock_rate;
+
 		enum class InterruptRate {
 			OnekHz,
 			FiftyHz,
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index d90eb0450..48019ec10 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -400,7 +400,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 							interrupt_state_ &= ~*cycle.value;
 							update_interrupts();
 
-							if(interrupt_mask_ & 0x45) {
+							if(interrupt_mask_ & 0x41) {
 								printf("Unimplemented interrupts requested: %02x\n", interrupt_mask_ & 0x45);
 							}
 						break;
@@ -412,7 +412,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 							printf("TODO: printer output %02x\n", *cycle.value);
 						break;
 						case 0xbf:
-							printf("TODO: Dave sysconfig %02x\n", *cycle.value);
+							// TODO: onboard RAM, Dave 8/12Mhz select.
 							switch((*cycle.value >> 2)&3) {
 								default:	wait_mode_ = WaitMode::None;			break;
 								case 0:		wait_mode_ = WaitMode::OnAllAccesses;	break;

From 116e0f0105fc4af7d1cf32e26a854947ce32c2f4 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 22:08:38 -0400
Subject: [PATCH 100/117] Interupts 1kHz and 50Hz interrupts, while edging
 towards tone generator interrupts.

---
 Machines/Enterprise/Dave.cpp | 22 +++++++++++++++++++---
 Machines/Enterprise/Dave.hpp |  5 +++--
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index d4b447bbf..513f0fcbc 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -214,6 +214,8 @@ void TimedInterruptSource::write(uint16_t address, uint8_t value) {
 		case 7:
 			channels_[0].sync = value & 0x01;
 			channels_[1].sync = value & 0x02;
+
+			// TODO: a hard cut-over here if switching to tracking a tone generator.
 			rate_ = InterruptRate((value >> 5) & 3);
 		break;
 	}
@@ -227,10 +229,24 @@ void TimedInterruptSource::run_for(Cycles cycles) {
 		one_hz_offset_ += clock_rate;
 	}
 
-	// TODO: update the programmable-frequency interrupt.
+	// TODO: shadow update the two tone channels.
+
+	// Update the programmable-frequency interrupt.
+	programmable_offset_ -= cycles.as<int>();
+	if(programmable_offset_ < 0) {
+		interrupts_ |= uint8_t(Interrupt::VariableFrequency);
+
+		switch(rate_) {
+			case InterruptRate::OnekHz:			programmable_offset_ = 249;					break;
+			case InterruptRate::FiftyHz:		programmable_offset_ = 4999;				break;
+			case InterruptRate::ToneGenerator0: programmable_offset_ = channels_[0].value;	break;
+			case InterruptRate::ToneGenerator1: programmable_offset_ = channels_[1].value;	break;
+		}
+	}
 }
 
 Cycles TimedInterruptSource::get_next_sequence_point() const {
-	// TODO: support the programmable-frequency interrupt.
-	return one_hz_offset_;
+	// To match normal tone generator logic: the programmable timer will
+	// generate activity when it underflows, not when it hits zero.
+	return (programmable_offset_+1) < one_hz_offset_.as<int>() ? Cycles(programmable_offset_+1) : one_hz_offset_;
 }
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index 47b3e82df..f9fa19116 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -133,6 +133,7 @@ class TimedInterruptSource {
 		static constexpr Cycles clock_rate{250000};
 
 		Cycles one_hz_offset_ = clock_rate;
+		uint16_t programmable_offset_ = 0;
 
 		enum class InterruptRate {
 			OnekHz,
@@ -142,8 +143,8 @@ class TimedInterruptSource {
 		} rate_ = InterruptRate::OnekHz;
 
 		struct Channel {
-			uint16_t value, reload;
-			bool sync;
+			uint16_t value = 100, reload = 100;
+			bool sync = false;
 		} channels_[2];
 };
 

From b93575bbcc0513814246590e121954fcea4904a9 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 22:33:20 -0400
Subject: [PATCH 101/117] Spots that b0 and b2 of 0xb4 are 'dividers', not
 enables.

---
 Machines/Enterprise/Dave.cpp       | 15 ++++++++++++---
 Machines/Enterprise/Dave.hpp       |  6 +++++-
 Machines/Enterprise/Enterprise.cpp |  2 +-
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 513f0fcbc..7a1bec51e 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -234,11 +234,14 @@ void TimedInterruptSource::run_for(Cycles cycles) {
 	// Update the programmable-frequency interrupt.
 	programmable_offset_ -= cycles.as<int>();
 	if(programmable_offset_ < 0) {
-		interrupts_ |= uint8_t(Interrupt::VariableFrequency);
+		if(programmable_level_) {
+			interrupts_ |= uint8_t(Interrupt::VariableFrequency);
+		}
+		programmable_level_ ^= true;
 
 		switch(rate_) {
-			case InterruptRate::OnekHz:			programmable_offset_ = 249;					break;
-			case InterruptRate::FiftyHz:		programmable_offset_ = 4999;				break;
+			case InterruptRate::OnekHz:			programmable_offset_ = 124;					break;
+			case InterruptRate::FiftyHz:		programmable_offset_ = 2499;				break;
 			case InterruptRate::ToneGenerator0: programmable_offset_ = channels_[0].value;	break;
 			case InterruptRate::ToneGenerator1: programmable_offset_ = channels_[1].value;	break;
 		}
@@ -250,3 +253,9 @@ Cycles TimedInterruptSource::get_next_sequence_point() const {
 	// generate activity when it underflows, not when it hits zero.
 	return (programmable_offset_+1) < one_hz_offset_.as<int>() ? Cycles(programmable_offset_+1) : one_hz_offset_;
 }
+
+uint8_t TimedInterruptSource::get_divider_state() {
+	return
+		(one_hz_offset_ < half_clock_rate ? 0x4 : 0x0) |
+		(programmable_level_ ? 0x1 : 0x0);
+}
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index f9fa19116..c2a0873d5 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -122,6 +122,7 @@ class TimedInterruptSource {
 		void write(uint16_t address, uint8_t value);
 
 		uint8_t get_new_interrupts();
+		uint8_t get_divider_state();
 
 		void run_for(Cycles);
 
@@ -131,9 +132,12 @@ class TimedInterruptSource {
 		uint8_t interrupts_ = 0;
 
 		static constexpr Cycles clock_rate{250000};
+		static constexpr Cycles half_clock_rate{125000};
 
 		Cycles one_hz_offset_ = clock_rate;
-		uint16_t programmable_offset_ = 0;
+
+		int programmable_offset_ = 0;
+		bool programmable_level_ = false;
 
 		enum class InterruptRate {
 			OnekHz,
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 48019ec10..87ecbe20a 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -342,7 +342,7 @@ template <bool has_disk_controller> class ConcreteMachine:
 						case 0xb3:	*cycle.value = pages_[3];	break;
 
 						case 0xb4:
-							*cycle.value = interrupt_mask_ | interrupt_state_;
+							*cycle.value = (interrupt_mask_ & 0xf0) | dave_timer_->get_divider_state() | interrupt_state_;
 						break;
 						case 0xb5:
 							if(active_key_line_ < key_lines_.size()) {

From 7de69e9874ba457538dace6684f5c497bf095e0b Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 23:09:11 -0400
Subject: [PATCH 102/117] Makes an attempt to round out the timed interrupts.

---
 Machines/Enterprise/Dave.cpp | 83 +++++++++++++++++++++++++++---------
 Machines/Enterprise/Dave.hpp |  4 +-
 2 files changed, 67 insertions(+), 20 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 7a1bec51e..f3b7938cf 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -211,16 +211,49 @@ void TimedInterruptSource::write(uint16_t address, uint8_t value) {
 			channels_[address >> 1].reload = uint16_t((channels_[address >> 1].reload & 0x00ff) | ((value & 0xf) << 8));
 		break;
 
-		case 7:
+		case 7: {
 			channels_[0].sync = value & 0x01;
 			channels_[1].sync = value & 0x02;
 
-			// TODO: a hard cut-over here if switching to tracking a tone generator.
-			rate_ = InterruptRate((value >> 5) & 3);
-		break;
+			const InterruptRate rate = InterruptRate((value >> 5) & 3);
+			if(rate != rate_) {
+				rate_ = InterruptRate((value >> 5) & 3);
+
+				if(rate_ >= InterruptRate::ToneGenerator0) {
+					programmable_level_ = channels_[int(rate_) - int(InterruptRate::ToneGenerator0)].level;
+				} else {
+					// TODO: eliminate copy and paste from below.
+					switch(rate_) {
+						case InterruptRate::OnekHz:			programmable_offset_ = 125;					break;
+						case InterruptRate::FiftyHz:		programmable_offset_ = 2500;				break;
+						default: break;
+					}
+				}
+			}
+		} break;
 	}
 }
 
+void TimedInterruptSource::update_channel(int c, bool is_linked, int decrement) {
+	if(channels_[c].sync) {
+		channels_[c].value = channels_[c].reload;
+	} else {
+		channels_[c].value -= decrement;
+		if(channels_[c].value < 0) {
+			channels_[c].value += channels_[c].reload + 1;
+
+			if(is_linked) {
+				if(channels_[c].level) {
+					interrupts_ |= uint8_t(Interrupt::VariableFrequency);
+				}
+				programmable_level_ = channels_[c].level;
+			}
+			channels_[c].value ^= true;
+		}
+	}
+
+}
+
 void TimedInterruptSource::run_for(Cycles cycles) {
 	// Update the 1Hz interrupt.
 	one_hz_offset_ -= cycles;
@@ -229,29 +262,41 @@ void TimedInterruptSource::run_for(Cycles cycles) {
 		one_hz_offset_ += clock_rate;
 	}
 
-	// TODO: shadow update the two tone channels.
+	// Update the two tone channels.
+	update_channel(0, rate_ == InterruptRate::ToneGenerator0, cycles.as<int>());
+	update_channel(1, rate_ == InterruptRate::ToneGenerator1, cycles.as<int>());
 
 	// Update the programmable-frequency interrupt.
-	programmable_offset_ -= cycles.as<int>();
-	if(programmable_offset_ < 0) {
-		if(programmable_level_) {
-			interrupts_ |= uint8_t(Interrupt::VariableFrequency);
-		}
-		programmable_level_ ^= true;
+	if(rate_ < InterruptRate::ToneGenerator0) {
+		programmable_offset_ -= cycles.as<int>();
+		if(programmable_offset_ <= 0) {
+			if(programmable_level_) {
+				interrupts_ |= uint8_t(Interrupt::VariableFrequency);
+			}
+			programmable_level_ ^= true;
 
-		switch(rate_) {
-			case InterruptRate::OnekHz:			programmable_offset_ = 124;					break;
-			case InterruptRate::FiftyHz:		programmable_offset_ = 2499;				break;
-			case InterruptRate::ToneGenerator0: programmable_offset_ = channels_[0].value;	break;
-			case InterruptRate::ToneGenerator1: programmable_offset_ = channels_[1].value;	break;
+			switch(rate_) {
+				case InterruptRate::OnekHz:			programmable_offset_ = 125;					break;
+				case InterruptRate::FiftyHz:		programmable_offset_ = 2500;				break;
+				default: break;
+			}
 		}
 	}
 }
 
 Cycles TimedInterruptSource::get_next_sequence_point() const {
-	// To match normal tone generator logic: the programmable timer will
-	// generate activity when it underflows, not when it hits zero.
-	return (programmable_offset_+1) < one_hz_offset_.as<int>() ? Cycles(programmable_offset_+1) : one_hz_offset_;
+	int result = one_hz_offset_.as<int>();
+
+	if(rate_ < InterruptRate::ToneGenerator0) {
+		result = std::min(result, programmable_offset_);
+	}
+
+	// To match normal tone generator logic: the tone generators will
+	// generate activity when they underflow, not when they hits zero.
+	result = std::min(result, channels_[0].value + 1);
+	result = std::min(result, channels_[1].value + 1);
+
+	return Cycles(result);
 }
 
 uint8_t TimedInterruptSource::get_divider_state() {
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index c2a0873d5..cf3d518ea 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -136,7 +136,7 @@ class TimedInterruptSource {
 
 		Cycles one_hz_offset_ = clock_rate;
 
-		int programmable_offset_ = 0;
+		int programmable_offset_ = std::numeric_limits<int>::max();
 		bool programmable_level_ = false;
 
 		enum class InterruptRate {
@@ -149,7 +149,9 @@ class TimedInterruptSource {
 		struct Channel {
 			uint16_t value = 100, reload = 100;
 			bool sync = false;
+			bool level = false;
 		} channels_[2];
+		void update_channel(int c, bool is_linked, int decrement);
 };
 
 }

From 36805cb1205d47d10f5f8d1445cbb6fa53a96252 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 27 Jun 2021 23:21:00 -0400
Subject: [PATCH 103/117] Correct tone channel interrupts, remove dead warning.

---
 Machines/Enterprise/Dave.cpp       | 6 ++++--
 Machines/Enterprise/Dave.hpp       | 2 +-
 Machines/Enterprise/Enterprise.cpp | 4 ----
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index f3b7938cf..81b0f64da 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -234,12 +234,14 @@ void TimedInterruptSource::write(uint16_t address, uint8_t value) {
 	}
 }
 
+// TODO: don't muck about with update_channel if channels have a reload value of 0.
+
 void TimedInterruptSource::update_channel(int c, bool is_linked, int decrement) {
 	if(channels_[c].sync) {
 		channels_[c].value = channels_[c].reload;
 	} else {
 		channels_[c].value -= decrement;
-		if(channels_[c].value < 0) {
+		while(channels_[c].value < 0) {
 			channels_[c].value += channels_[c].reload + 1;
 
 			if(is_linked) {
@@ -248,7 +250,7 @@ void TimedInterruptSource::update_channel(int c, bool is_linked, int decrement)
 				}
 				programmable_level_ = channels_[c].level;
 			}
-			channels_[c].value ^= true;
+			channels_[c].level ^= true;
 		}
 	}
 
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index cf3d518ea..b0d986e1f 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -147,7 +147,7 @@ class TimedInterruptSource {
 		} rate_ = InterruptRate::OnekHz;
 
 		struct Channel {
-			uint16_t value = 100, reload = 100;
+			int value = 100, reload = 100;
 			bool sync = false;
 			bool level = false;
 		} channels_[2];
diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 87ecbe20a..bf2baff9f 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -399,10 +399,6 @@ template <bool has_disk_controller> class ConcreteMachine:
 							interrupt_mask_ = *cycle.value & 0x55;
 							interrupt_state_ &= ~*cycle.value;
 							update_interrupts();
-
-							if(interrupt_mask_ & 0x41) {
-								printf("Unimplemented interrupts requested: %02x\n", interrupt_mask_ & 0x45);
-							}
 						break;
 						case 0xb5:
 							active_key_line_ = *cycle.value & 0xf;

From daa0737ce44d4d611afff2067974c71f56057957 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 28 Jun 2021 19:00:51 -0400
Subject: [PATCH 104/117] Ensure addresses tick upwards even during sync/burst;
 correct 2/4/8bpp character sizing.

---
 Machines/Enterprise/Nick.cpp | 48 +++++++++++++++---------------------
 Machines/Enterprise/Nick.hpp |  8 +++---
 2 files changed, 24 insertions(+), 32 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index 69138eede..ea0f31511 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -113,6 +113,8 @@ void Nick::run_for(Cycles duration) {
 	// TODO: test here for window < 57? Or maybe just nudge up left_/right_margin_ if they
 	// exactly equal 57?
 #define add_window(x)											\
+	line_data_pointer_[0] += is_sync_or_pixels_ * line_data_per_column_increments_[0] * (x);	\
+	line_data_pointer_[1] += is_sync_or_pixels_ * line_data_per_column_increments_[1] * (x);	\
 	window += x;												\
 	if(window == left_margin_) is_sync_or_pixels_ = true;		\
 	if(window == right_margin_) is_sync_or_pixels_ = false;
@@ -170,15 +172,10 @@ void Nick::run_for(Cycles duration) {
 							break;
 
 							case Mode::LPixel:
-								column_size_ = 8 / bpp_;
-								line_data_per_column_increments_[0] = 1;
-								line_data_per_column_increments_[1] = 0;
-							break;
-
 							case Mode::CH64:
 							case Mode::CH128:
 							case Mode::CH256:
-								column_size_ = 8;
+								column_size_ = 8 / bpp_;
 								line_data_per_column_increments_[0] = 1;
 								line_data_per_column_increments_[1] = 0;
 							break;
@@ -362,13 +359,10 @@ void Nick::run_for(Cycles duration) {
 									set_output_type(OutputType::Pixels, true);
 								}
 								columns_remaining -= output_duration;
+								add_window(output_duration);
 							} else {
-								// Ensure line data pointers are advanced as if there hadn't been back pressure on
-								// pixel rendering.
-								line_data_pointer_[0] += columns_remaining * line_data_per_column_increments_[0];
-								line_data_pointer_[1] += columns_remaining * line_data_per_column_increments_[1];
-
 								output_duration_ += columns_remaining;
+								add_window(columns_remaining);
 								columns_remaining = 0;
 							}
 						}
@@ -382,9 +376,9 @@ void Nick::run_for(Cycles duration) {
 #undef DispatchBpp
 					} else {
 						output_duration_ += next_event - window;
+						add_window(next_event - window);
 					}
 
-					add_window(next_event - window);
 					set_output_type(is_sync_or_pixels_ ? OutputType::Pixels : OutputType::Border);
 				}
 			}
@@ -392,6 +386,8 @@ void Nick::run_for(Cycles duration) {
 
 		// Check for end of line.
 		if(!horizontal_counter_) {
+			assert(window == 57);
+
 			++lines_remaining_;
 			if(!lines_remaining_) {
 				should_reload_line_parameters_ = true;
@@ -523,12 +519,16 @@ Outputs::Display::ScanStatus Nick::get_scaled_scan_status() const {
 	target[0] = mapped_colour(x);	\
 	++target
 
-template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int columns) {
+template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int columns) const {
 	static_assert(bpp == 1 || bpp == 2 || bpp == 4 || bpp == 8);
 
+	int index = 0;
 	for(int c = 0; c < columns; c++) {
-		uint8_t pixels[2] = { ram_[line_data_pointer_[0]], ram_[(line_data_pointer_[0]+1) & 0xffff] };
-		line_data_pointer_[0] += is_lpixel ? 1 : 2;
+		uint8_t pixels[2] = {
+			ram_[(line_data_pointer_[0] + index) & 0xffff],
+			ram_[(line_data_pointer_[0] + index + 1) & 0xffff]
+		};
+		index += is_lpixel ? 1 : 2;
 
 		switch(bpp) {
 			default:
@@ -568,21 +568,16 @@ template <int bpp, bool is_lpixel> void Nick::output_pixel(uint16_t *target, int
 	}
 }
 
-template <int bpp, int index_bits> void Nick::output_character(uint16_t *target, int columns) {
+template <int bpp, int index_bits> void Nick::output_character(uint16_t *target, int columns) const {
 	static_assert(bpp == 1 || bpp == 2 || bpp == 4 || bpp == 8);
 
 	for(int c = 0; c < columns; c++) {
-		const uint8_t character = ram_[line_data_pointer_[0]];
-		++line_data_pointer_[0];
-
+		const uint8_t character = ram_[(line_data_pointer_[0] + c) & 0xffff];
 		const uint8_t pixels = ram_[(
 			(line_data_pointer_[1] << index_bits) +
 			(character & ((1 << index_bits) - 1))
 		) & 0xffff];
 
-		// TODO: below looks repetitious of the above, but I've yet to factor in
-		// ALTINDs and [M/L]SBALTs, so I'll correct for factoring when I've done that.
-
 		switch(bpp) {
 			default:
 				assert(false);
@@ -601,15 +596,12 @@ template <int bpp, int index_bits> void Nick::output_character(uint16_t *target,
 	}
 }
 
-template <int bpp> void Nick::output_attributed(uint16_t *target, int columns) {
+template <int bpp> void Nick::output_attributed(uint16_t *target, int columns) const {
 	static_assert(bpp == 1 || bpp == 2 || bpp == 4 || bpp == 8);
 
 	for(int c = 0; c < columns; c++) {
-		const uint8_t pixels = ram_[line_data_pointer_[1]];
-		const uint8_t attributes = ram_[line_data_pointer_[0]];
-
-		++line_data_pointer_[0];
-		++line_data_pointer_[1];
+		const uint8_t pixels = ram_[(line_data_pointer_[1] + c) & 0xffff];
+		const uint8_t attributes = ram_[(line_data_pointer_[0] + c) & 0xffff];
 
 		const uint16_t palette[2] = {
 			palette_[attributes >> 4], palette_[attributes & 0x0f]
diff --git a/Machines/Enterprise/Nick.hpp b/Machines/Enterprise/Nick.hpp
index eef4f19b0..b9ce44439 100644
--- a/Machines/Enterprise/Nick.hpp
+++ b/Machines/Enterprise/Nick.hpp
@@ -81,7 +81,7 @@ class Nick {
 		int border_duration_ = 0;
 
 		// The destination for new pixels.
-		static constexpr int allocation_size = 320;
+		static constexpr int allocation_size = 336;
 		static_assert((allocation_size % 16) == 0, "Allocation size must be a multiple of 16");
 		uint16_t *pixel_pointer_ = nullptr, *allocated_pointer_ = nullptr;
 
@@ -97,9 +97,9 @@ class Nick {
 		uint16_t palette_[16]{};
 
 		// Specific outputters.
-		template <int bpp, bool is_lpixel> void output_pixel(uint16_t *target, int columns);
-		template <int bpp, int index_bits> void output_character(uint16_t *target, int columns);
-		template <int bpp> void output_attributed(uint16_t *target, int columns);
+		template <int bpp, bool is_lpixel> void output_pixel(uint16_t *target, int columns) const;
+		template <int bpp, int index_bits> void output_character(uint16_t *target, int columns) const;
+		template <int bpp> void output_attributed(uint16_t *target, int columns) const;
 };
 
 

From 919e211bc4c3698abe84aa9aae86a10a003ff752 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 28 Jun 2021 19:30:12 -0400
Subject: [PATCH 105/117] Reduces number of interrupt-related sequence points.

---
 Machines/Enterprise/Dave.cpp | 34 +++++++++++++++-------------------
 Machines/Enterprise/Dave.hpp |  7 +++++++
 2 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 81b0f64da..38a151d87 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -222,12 +222,7 @@ void TimedInterruptSource::write(uint16_t address, uint8_t value) {
 				if(rate_ >= InterruptRate::ToneGenerator0) {
 					programmable_level_ = channels_[int(rate_) - int(InterruptRate::ToneGenerator0)].level;
 				} else {
-					// TODO: eliminate copy and paste from below.
-					switch(rate_) {
-						case InterruptRate::OnekHz:			programmable_offset_ = 125;					break;
-						case InterruptRate::FiftyHz:		programmable_offset_ = 2500;				break;
-						default: break;
-					}
+					programmable_offset_ = programmble_reload(rate_);
 				}
 			}
 		} break;
@@ -240,6 +235,8 @@ void TimedInterruptSource::update_channel(int c, bool is_linked, int decrement)
 	if(channels_[c].sync) {
 		channels_[c].value = channels_[c].reload;
 	} else {
+		// TODO: the while loop below is far from efficient.
+
 		channels_[c].value -= decrement;
 		while(channels_[c].value < 0) {
 			channels_[c].value += channels_[c].reload + 1;
@@ -276,12 +273,7 @@ void TimedInterruptSource::run_for(Cycles cycles) {
 				interrupts_ |= uint8_t(Interrupt::VariableFrequency);
 			}
 			programmable_level_ ^= true;
-
-			switch(rate_) {
-				case InterruptRate::OnekHz:			programmable_offset_ = 125;					break;
-				case InterruptRate::FiftyHz:		programmable_offset_ = 2500;				break;
-				default: break;
-			}
+			programmable_offset_ = programmble_reload(rate_);
 		}
 	}
 }
@@ -289,15 +281,19 @@ void TimedInterruptSource::run_for(Cycles cycles) {
 Cycles TimedInterruptSource::get_next_sequence_point() const {
 	int result = one_hz_offset_.as<int>();
 
-	if(rate_ < InterruptRate::ToneGenerator0) {
-		result = std::min(result, programmable_offset_);
+	switch(rate_) {
+		case InterruptRate::OnekHz:
+		case InterruptRate::FiftyHz:
+			result = std::min(result, programmable_offset_);
+		break;
+		case InterruptRate::ToneGenerator0:
+		case InterruptRate::ToneGenerator1: {
+			const auto& channel = channels_[int(rate_) - int(InterruptRate::ToneGenerator0)];
+			const int cycles_until_interrupt = (channel.value + 1) + (channel.level ? 0 : channel.reload + 1);
+			result = std::min(result, cycles_until_interrupt);
+		} break;
 	}
 
-	// To match normal tone generator logic: the tone generators will
-	// generate activity when they underflow, not when they hits zero.
-	result = std::min(result, channels_[0].value + 1);
-	result = std::min(result, channels_[1].value + 1);
-
 	return Cycles(result);
 }
 
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index b0d986e1f..beb1db4fd 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -152,6 +152,13 @@ class TimedInterruptSource {
 			bool level = false;
 		} channels_[2];
 		void update_channel(int c, bool is_linked, int decrement);
+		static constexpr int programmble_reload(InterruptRate rate) {
+			switch(rate) {
+				default: return 0;
+				case InterruptRate::OnekHz:		return 125;
+				case InterruptRate::FiftyHz:	return 2500;
+			}
+		}
 };
 
 }

From 3c59042388f573800638b5e63ae376548237befd Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 28 Jun 2021 21:08:41 -0400
Subject: [PATCH 106/117] Fixes initial state for 1kHz.

---
 Machines/Enterprise/Dave.cpp | 21 ++++++++-------------
 Machines/Enterprise/Dave.hpp |  5 ++---
 2 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 38a151d87..995ce29a5 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -235,22 +235,17 @@ void TimedInterruptSource::update_channel(int c, bool is_linked, int decrement)
 	if(channels_[c].sync) {
 		channels_[c].value = channels_[c].reload;
 	} else {
-		// TODO: the while loop below is far from efficient.
-
-		channels_[c].value -= decrement;
-		while(channels_[c].value < 0) {
-			channels_[c].value += channels_[c].reload + 1;
-
-			if(is_linked) {
-				if(channels_[c].level) {
-					interrupts_ |= uint8_t(Interrupt::VariableFrequency);
-				}
-				programmable_level_ = channels_[c].level;
+		if(decrement <= channels_[c].value) {
+			channels_[c].value -= decrement;
+		} else {
+			const int num_flips = (decrement - (channels_[c].value + 1)) / (channels_[c].reload + 1);
+			if(is_linked && num_flips + channels_[c].level >= 2) {
+				interrupts_ |= uint8_t(Interrupt::VariableFrequency);
 			}
-			channels_[c].level ^= true;
+			channels_[c].level ^= (num_flips & 1);
+			channels_[c].value = (decrement - (channels_[c].value + 1)) % (channels_[c].reload + 1);
 		}
 	}
-
 }
 
 void TimedInterruptSource::run_for(Cycles cycles) {
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index beb1db4fd..a280665af 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -136,15 +136,14 @@ class TimedInterruptSource {
 
 		Cycles one_hz_offset_ = clock_rate;
 
-		int programmable_offset_ = std::numeric_limits<int>::max();
-		bool programmable_level_ = false;
-
 		enum class InterruptRate {
 			OnekHz,
 			FiftyHz,
 			ToneGenerator0,
 			ToneGenerator1,
 		} rate_ = InterruptRate::OnekHz;
+		int programmable_offset_ = programmble_reload(InterruptRate::OnekHz);
+		bool programmable_level_ = false;
 
 		struct Channel {
 			int value = 100, reload = 100;

From a5c57e777ec1c36630bbd6c04531496806ec1bca Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 28 Jun 2021 21:24:13 -0400
Subject: [PATCH 107/117] VRES appears to work negatively in attribute mode
 too.

---
 Machines/Enterprise/Nick.cpp | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/Machines/Enterprise/Nick.cpp b/Machines/Enterprise/Nick.cpp
index ea0f31511..02628ead0 100644
--- a/Machines/Enterprise/Nick.cpp
+++ b/Machines/Enterprise/Nick.cpp
@@ -412,16 +412,10 @@ void Nick::run_for(Cycles duration) {
 					++line_data_pointer_[1];
 				break;
 
-				case Mode::Attr:
-					// Reload the attribute address if VRES is set.
-					if(vres_) {
-						line_data_pointer_[0] = start_line_data_pointer_[0];
-					}
-				break;
-
 				case Mode::Pixel:
 				case Mode::LPixel:
-					// If VRES is clear, reload the pixel address.
+				case Mode::Attr:
+					// Reload the pixel or attribute address if VRES is clear.
 					if(!vres_) {
 						line_data_pointer_[0] = start_line_data_pointer_[0];
 					}

From 49f0ab0f158f4c5292528a150bb9ab87636c833e Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 28 Jun 2021 21:31:55 -0400
Subject: [PATCH 108/117] Add note to self.

Although I still think there may be some issue lurking.
---
 Machines/Enterprise/Dave.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 995ce29a5..5e142fa21 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -293,6 +293,8 @@ Cycles TimedInterruptSource::get_next_sequence_point() const {
 }
 
 uint8_t TimedInterruptSource::get_divider_state() {
+	// one_hz_offset_ counts downwards, so when it crosses the halfway mark
+	// it enters the high part of its wave.
 	return
 		(one_hz_offset_ < half_clock_rate ? 0x4 : 0x0) |
 		(programmable_level_ ? 0x1 : 0x0);

From 5351ac560fce0ffa4eb6fd4ea5cbdebd560ade63 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 28 Jun 2021 21:40:12 -0400
Subject: [PATCH 109/117] Ensure the motor goes off for unselected drives.

---
 Machines/Enterprise/EXDos.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/EXDos.cpp b/Machines/Enterprise/EXDos.cpp
index 015626e2a..1bc80ef41 100644
--- a/Machines/Enterprise/EXDos.cpp
+++ b/Machines/Enterprise/EXDos.cpp
@@ -48,8 +48,13 @@ void EXDos::set_control_register(uint8_t control) {
 		get_drive(c).set_head(head);
 	}
 
-	// Select drive.
+	// Select drive, ensuring handover of the motor-on state.
+	const bool motor_state = get_drive().get_motor_on();
+	for_all_drives([] (Storage::Disk::Drive &drive, size_t) {
+		drive.set_motor_on(false);
+	});
 	set_drive(control & 0xf);
+	get_drive().set_motor_on(motor_state);
 }
 
 uint8_t EXDos::get_control_register() {

From 1119779c8b6036aaaeb65fe3a819ae7bf70cc8ae Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 28 Jun 2021 21:47:53 -0400
Subject: [PATCH 110/117] Ensure EXDOS card is completely disabled if no FDC is
 present.

---
 Machines/Enterprise/Enterprise.cpp | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index bf2baff9f..c9b77232a 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -329,11 +329,19 @@ template <bool has_disk_controller> class ConcreteMachine:
 
 						case 0x10:	case 0x11:	case 0x12:	case 0x13:
 						case 0x14:	case 0x15:	case 0x16:	case 0x17:
-							*cycle.value = exdos_.read(address);
+							if constexpr (has_disk_controller) {
+								*cycle.value = exdos_.read(address);
+							} else {
+								*cycle.value = 0xff;
+							}
 						break;
 						case 0x18:	case 0x19:	case 0x1a:	case 0x1b:
 						case 0x1c:	case 0x1d:	case 0x1e:	case 0x1f:
-							*cycle.value = exdos_.get_control_register();
+							if constexpr (has_disk_controller) {
+								*cycle.value = exdos_.get_control_register();
+							} else {
+								*cycle.value = 0xff;
+							}
 						break;
 
 						case 0xb0:	*cycle.value = pages_[0];	break;
@@ -367,11 +375,15 @@ template <bool has_disk_controller> class ConcreteMachine:
 
 						case 0x10:	case 0x11:	case 0x12:	case 0x13:
 						case 0x14:	case 0x15:	case 0x16:	case 0x17:
-							exdos_.write(address, *cycle.value);
+							if constexpr(has_disk_controller) {
+								exdos_.write(address, *cycle.value);
+							}
 						break;
 						case 0x18:	case 0x19:	case 0x1a:	case 0x1b:
 						case 0x1c:	case 0x1d:	case 0x1e:	case 0x1f:
-							 exdos_.set_control_register(*cycle.value);
+							if constexpr(has_disk_controller) {
+								exdos_.set_control_register(*cycle.value);
+							}
 						break;
 
 						case 0x80:	case 0x81:	case 0x82:	case 0x83:

From 2c139ad931c6c139b333da997907651f942f0fae Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 28 Jun 2021 22:03:06 -0400
Subject: [PATCH 111/117] Adds some notes to self.

I think I'm starting to find enough information to handle tapes.
---
 Machines/Enterprise/Enterprise.cpp | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index c9b77232a..51338790f 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -359,10 +359,19 @@ template <bool has_disk_controller> class ConcreteMachine:
 								*cycle.value = 0xff;
 							}
 						break;
-						case 0xb6:
-							// TODO: joystick input.
+						case 0xb6: {
+							// TODO: selected keyboard row, 0 to 9, should return one bit of joystick
+							// input. That being the case:
+							//
+							//	b0:		joystick input
+							//	b1, b2:	unused (in theory read from control port, but not used by any hardware)
+							//	b3:		0 = printer ready; 1 = not ready
+							//	b4:		serial, data in
+							//	b5:		serial, status in
+							//	b6:		tape input volume level, 0 = high, 1 = low
+							//	b7:		tape data input
 							*cycle.value = 0xff;
-						break;
+						} break;
 					}
 				break;
 
@@ -414,11 +423,22 @@ template <bool has_disk_controller> class ConcreteMachine:
 						break;
 						case 0xb5:
 							active_key_line_ = *cycle.value & 0xf;
-							// TODO: printer strobe, type sound, REM switches.
+							// TODO:
+							//
+							//	b4:	strobe output for printer
+							//	b5:	tape sound control (?)
+							//	b6:	tape motor control 1, 1 = on
+							//	b7: tape motor control 2, 1 = on
 						break;
 						case 0xb6:
+							// Just 8 bits of printer data.
 							printf("TODO: printer output %02x\n", *cycle.value);
 						break;
+						case 0xb7:
+							// b0 = serial data out
+							// b1 = serial status out
+							printf("TODO: serial output %02x\n", *cycle.value);
+						break;
 						case 0xbf:
 							// TODO: onboard RAM, Dave 8/12Mhz select.
 							switch((*cycle.value >> 2)&3) {

From 7f08218b28da0cd8ad05e63df3da9ae404b12623 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 28 Jun 2021 22:10:11 -0400
Subject: [PATCH 112/117] The Nick interrupt input also seems to be a live
 poll, not a retrieval of the mask.

This corrects the two pieces of software I knew not to be working.
---
 Machines/Enterprise/Enterprise.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Enterprise.cpp b/Machines/Enterprise/Enterprise.cpp
index 51338790f..ef2752d51 100644
--- a/Machines/Enterprise/Enterprise.cpp
+++ b/Machines/Enterprise/Enterprise.cpp
@@ -350,7 +350,10 @@ template <bool has_disk_controller> class ConcreteMachine:
 						case 0xb3:	*cycle.value = pages_[3];	break;
 
 						case 0xb4:
-							*cycle.value = (interrupt_mask_ & 0xf0) | dave_timer_->get_divider_state() | interrupt_state_;
+							*cycle.value =
+								(nick_->get_interrupt_line() ? 0x00 : 0x10) |
+								dave_timer_->get_divider_state() |
+								interrupt_state_;
 						break;
 						case 0xb5:
 							if(active_key_line_ < key_lines_.size()) {

From 8ce8fbd977b7eb01c20343d2b2d2029be5329288 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 29 Jun 2021 15:41:08 -0400
Subject: [PATCH 113/117] Provide correct input when one of the tone generators
 is the interrupt source.

---
 Machines/Enterprise/Dave.cpp | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 5e142fa21..d6ef31cc4 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -293,9 +293,23 @@ Cycles TimedInterruptSource::get_next_sequence_point() const {
 }
 
 uint8_t TimedInterruptSource::get_divider_state() {
+	bool programmable_flag = false;
+	switch(rate_) {
+		case InterruptRate::OnekHz:
+		case InterruptRate::FiftyHz:
+			programmable_flag = programmable_level_;
+		break;
+		case InterruptRate::ToneGenerator0:
+			programmable_flag = channels_[0].level;
+		break;
+		case InterruptRate::ToneGenerator1:
+			programmable_flag = channels_[1].level;
+		break;
+	}
+
 	// one_hz_offset_ counts downwards, so when it crosses the halfway mark
 	// it enters the high part of its wave.
 	return
 		(one_hz_offset_ < half_clock_rate ? 0x4 : 0x0) |
-		(programmable_level_ ? 0x1 : 0x0);
+		(programmable_flag ? 0x1 : 0x0);
 }

From 3d8fc9952dc56076f9a5e8348d6730553d67a40a Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 29 Jun 2021 15:44:02 -0400
Subject: [PATCH 114/117] Remove dead TODO, correct for overflow position.

---
 Machines/Enterprise/Dave.cpp | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index d6ef31cc4..4f8f74ec8 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -229,8 +229,6 @@ void TimedInterruptSource::write(uint16_t address, uint8_t value) {
 	}
 }
 
-// TODO: don't muck about with update_channel if channels have a reload value of 0.
-
 void TimedInterruptSource::update_channel(int c, bool is_linked, int decrement) {
 	if(channels_[c].sync) {
 		channels_[c].value = channels_[c].reload;
@@ -238,12 +236,12 @@ void TimedInterruptSource::update_channel(int c, bool is_linked, int decrement)
 		if(decrement <= channels_[c].value) {
 			channels_[c].value -= decrement;
 		} else {
-			const int num_flips = (decrement - (channels_[c].value + 1)) / (channels_[c].reload + 1);
+			const int num_flips = (decrement - channels_[c].value) / (channels_[c].reload + 1);
 			if(is_linked && num_flips + channels_[c].level >= 2) {
 				interrupts_ |= uint8_t(Interrupt::VariableFrequency);
 			}
 			channels_[c].level ^= (num_flips & 1);
-			channels_[c].value = (decrement - (channels_[c].value + 1)) % (channels_[c].reload + 1);
+			channels_[c].value = (decrement - channels_[c].value) % (channels_[c].reload + 1);
 		}
 	}
 }

From ab059b63fd1ad5fbe49c50cbea804116d927596e Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 29 Jun 2021 20:36:28 -0400
Subject: [PATCH 115/117] Add Enterprise to Qt project file.

---
 OSBindings/Qt/ClockSignal.pro | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/OSBindings/Qt/ClockSignal.pro b/OSBindings/Qt/ClockSignal.pro
index 93b2239fc..6a7ae7d94 100644
--- a/OSBindings/Qt/ClockSignal.pro
+++ b/OSBindings/Qt/ClockSignal.pro
@@ -47,6 +47,7 @@ SOURCES += \
 	$$SRC/Analyser/Static/Commodore/*.cpp \
 	$$SRC/Analyser/Static/Disassembler/*.cpp \
 	$$SRC/Analyser/Static/DiskII/*.cpp \
+	$$SRC/Analyser/Static/Enterprise/*.cpp \
 	$$SRC/Analyser/Static/Macintosh/*.cpp \
 	$$SRC/Analyser/Static/MSX/*.cpp \
 	$$SRC/Analyser/Static/Oric/*.cpp \
@@ -92,6 +93,7 @@ SOURCES += \
 	$$SRC/Machines/Commodore/1540/Implementation/*.cpp \
 	$$SRC/Machines/Commodore/Vic-20/*.cpp \
 	$$SRC/Machines/Electron/*.cpp \
+	$$SRC/Machines/Enterprise/*.cpp \
 	$$SRC/Machines/MasterSystem/*.cpp \
 	$$SRC/Machines/MSX/*.cpp \
 	$$SRC/Machines/Oric/*.cpp \
@@ -166,6 +168,7 @@ HEADERS += \
 	$$SRC/Analyser/Static/Commodore/*.hpp \
 	$$SRC/Analyser/Static/Disassembler/*.hpp \
 	$$SRC/Analyser/Static/DiskII/*.hpp \
+	$$SRC/Analyser/Static/Enterprise/*.hpp \
 	$$SRC/Analyser/Static/Macintosh/*.hpp \
 	$$SRC/Analyser/Static/MSX/*.hpp \
 	$$SRC/Analyser/Static/Oric/*.hpp \
@@ -221,6 +224,7 @@ HEADERS += \
 	$$SRC/Machines/Commodore/1540/Implementation/*.hpp \
 	$$SRC/Machines/Commodore/Vic-20/*.hpp \
 	$$SRC/Machines/Electron/*.hpp \
+	$$SRC/Machines/Enterprise/*.hpp \
 	$$SRC/Machines/MasterSystem/*.hpp \
 	$$SRC/Machines/MSX/*.hpp \
 	$$SRC/Machines/Oric/*.hpp \

From a46ff5590d413a33c976e83ec6f7b34141df6938 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 29 Jun 2021 21:04:17 -0400
Subject: [PATCH 116/117] Adds Enterprise new machine dialogue for Qt.

---
 OSBindings/Qt/mainwindow.cpp |  40 ++++++
 OSBindings/Qt/mainwindow.h   |   1 +
 OSBindings/Qt/mainwindow.ui  | 270 ++++++++++++++++++++++++++---------
 3 files changed, 242 insertions(+), 69 deletions(-)

diff --git a/OSBindings/Qt/mainwindow.cpp b/OSBindings/Qt/mainwindow.cpp
index add5a4183..95bebc313 100644
--- a/OSBindings/Qt/mainwindow.cpp
+++ b/OSBindings/Qt/mainwindow.cpp
@@ -953,6 +953,7 @@ void MainWindow::setButtonPressed(int index, bool isPressed) {
 #include "../../Analyser/Static/AppleIIgs/Target.hpp"
 #include "../../Analyser/Static/AtariST/Target.hpp"
 #include "../../Analyser/Static/Commodore/Target.hpp"
+#include "../../Analyser/Static/Enterprise/Target.hpp"
 #include "../../Analyser/Static/Macintosh/Target.hpp"
 #include "../../Analyser/Static/MSX/Target.hpp"
 #include "../../Analyser/Static/Oric/Target.hpp"
@@ -973,6 +974,7 @@ void MainWindow::startMachine() {
 	TEST(amstradCPC);
 	TEST(atariST);
 	TEST(electron);
+	TEST(enterprise);
 	TEST(macintosh);
 	TEST(msx);
 	TEST(oric);
@@ -1057,6 +1059,38 @@ void MainWindow::start_electron() {
 	launchTarget(std::move(target));
 }
 
+void MainWindow::start_enterprise() {
+	using Target = Analyser::Static::Enterprise::Target;
+	auto target = std::make_unique<Target>();
+
+	switch(ui->enterpriseModelComboBox->currentIndex()) {
+		default:	target->model = Target::Model::Enterprise64;	break;
+		case 1:		target->model = Target::Model::Enterprise128;	break;
+		case 2:		target->model = Target::Model::Enterprise256;	break;
+	}
+
+	switch(ui->enterpriseEXOSComboBox->currentIndex()) {
+		default:	target->exos_version = Target::EXOSVersion::v10;	break;
+		case 1:		target->exos_version = Target::EXOSVersion::v20;	break;
+		case 2:		target->exos_version = Target::EXOSVersion::v21;	break;
+		case 3:		target->exos_version = Target::EXOSVersion::v23;	break;
+	}
+
+	switch(ui->enterpriseBASICComboBox->currentIndex()) {
+		default:	target->basic_version = Target::BASICVersion::None;	break;
+		case 1:		target->basic_version = Target::BASICVersion::v10;	break;
+		case 2:		target->basic_version = Target::BASICVersion::v11;	break;
+		case 3:		target->basic_version = Target::BASICVersion::v21;	break;
+	}
+
+	switch(ui->enterpriseDOSComboBox->currentIndex()) {
+		default:	target->dos = Target::DOS::None;	break;
+		case 1:		target->dos = Target::DOS::EXDOS;	break;
+	}
+
+	launchTarget(std::move(target));
+}
+
 void MainWindow::start_macintosh() {
 	using Target = Analyser::Static::Macintosh::Target;
 	auto target = std::make_unique<Target>();
@@ -1212,6 +1246,12 @@ void MainWindow::launchTarget(std::unique_ptr<Analyser::Static::Target> &&target
 	CheckBox(electronAP6CheckBox, "electron.hasAP6");					\
 	CheckBox(electronSidewaysRAMCheckBox, "electron.fillSidewaysRAM");	\
 																		\
+	/* Enterprise. */													\
+	ComboBox(enterpriseModelComboBox, "enterprise.model");				\
+	ComboBox(enterpriseEXOSComboBox, "enterprise.exos");				\
+	ComboBox(enterpriseBASICComboBox, "enterprise.basic");				\
+	ComboBox(enterpriseDOSComboBox, "enterprise.dos");					\
+																		\
 	/* Macintosh. */													\
 	ComboBox(macintoshModelComboBox, "macintosh.model");				\
 																		\
diff --git a/OSBindings/Qt/mainwindow.h b/OSBindings/Qt/mainwindow.h
index 24f3593e1..0fd3f6978 100644
--- a/OSBindings/Qt/mainwindow.h
+++ b/OSBindings/Qt/mainwindow.h
@@ -91,6 +91,7 @@ class MainWindow : public QMainWindow, public Outputs::Speaker::Speaker::Delegat
 		void start_amstradCPC();
 		void start_atariST();
 		void start_electron();
+		void start_enterprise();
 		void start_macintosh();
 		void start_msx();
 		void start_oric();
diff --git a/OSBindings/Qt/mainwindow.ui b/OSBindings/Qt/mainwindow.ui
index 931f8a73c..8929705fe 100644
--- a/OSBindings/Qt/mainwindow.ui
+++ b/OSBindings/Qt/mainwindow.ui
@@ -310,6 +310,138 @@
         </item>
        </layout>
       </widget>
+      <widget class="QWidget" name="enterpriseTab">
+       <attribute name="title">
+        <string>Enterprise</string>
+       </attribute>
+       <layout class="QVBoxLayout" name="enterpriseLayout">
+        <item>
+         <layout class="QHBoxLayout" name="enterpriseHorizontalLayout">
+          <item>
+           <layout class="QFormLayout" name="enterpriseFormLayout">
+            <item row="0" column="0">
+             <widget class="QLabel" name="enterpriseModelLabel">
+              <property name="text">
+               <string>Model:</string>
+              </property>
+             </widget>
+            </item>
+            <item row="0" column="1">
+             <widget class="QComboBox" name="enterpriseModelComboBox">
+              <item>
+               <property name="text">
+                <string>Enterprise 64</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>Enterprise 128</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>Enterprise 256</string>
+               </property>
+              </item>
+             </widget>
+            </item>
+            <item row="1" column="0">
+             <widget class="QLabel" name="enterpriseEXOSLabel">
+              <property name="text">
+               <string>EXOS:</string>
+              </property>
+             </widget>
+            </item>
+            <item row="1" column="1">
+             <widget class="QComboBox" name="enterpriseEXOSComboBox">
+              <item>
+               <property name="text">
+                <string>Version 1.0</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>Version 2.0</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>Version 2.1</string>
+               </property>
+              </item>
+             </widget>
+            </item>
+            <item row="2" column="0">
+             <widget class="QLabel" name="enterpriseBASICLabel">
+              <property name="text">
+               <string>BASIC:</string>
+              </property>
+             </widget>
+            </item>
+            <item row="2" column="1">
+             <widget class="QComboBox" name="enterpriseBASICComboBox">
+              <item>
+               <property name="text">
+                <string>None</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>Version 1.0</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>Version 1.1</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>Version 2.1</string>
+               </property>
+              </item>
+             </widget>
+            </item>
+            <item row="3" column="0">
+             <widget class="QLabel" name="enterpriseDOSLabel">
+              <property name="text">
+               <string>DOS:</string>
+              </property>
+             </widget>
+            </item>
+            <item row="3" column="1">
+             <widget class="QComboBox" name="enterpriseDOSComboBox">
+              <item>
+               <property name="text">
+                <string>None</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>EXDOS</string>
+               </property>
+              </item>
+             </widget>
+            </item>
+           </layout>
+          </item>
+          <item>
+           <spacer name="enterpriseHSpacer">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+            <property name="sizeHint" stdset="0">
+             <size>
+              <width>40</width>
+              <height>20</height>
+             </size>
+            </property>
+           </spacer>
+          </item>
+         </layout>
+        </item>
+       </layout>
+      </widget>
       <widget class="QWidget" name="macintoshTab">
        <attribute name="title">
         <string>Macintosh</string>
@@ -533,75 +665,6 @@
         </item>
        </layout>
       </widget>
-      <widget class="QWidget" name="spectrumTab">
-       <attribute name="title">
-        <string>Spectrum</string>
-       </attribute>
-       <layout class="QVBoxLayout" name="spectrumLayout">
-        <item>
-         <layout class="QHBoxLayout" name="spectrumHorizontalLayout">
-          <item>
-           <layout class="QFormLayout" name="spectrumFormLayout">
-            <item row="0" column="0">
-             <widget class="QLabel" name="spectrumModelLabel">
-              <property name="text">
-               <string>Model:</string>
-              </property>
-             </widget>
-            </item>
-            <item row="0" column="1">
-             <widget class="QComboBox" name="spectrumModelComboBox">
-              <item>
-               <property name="text">
-                <string>16kb</string>
-               </property>
-              </item>
-              <item>
-               <property name="text">
-                <string>48kb</string>
-               </property>
-              </item>
-              <item>
-               <property name="text">
-                <string>128kb</string>
-               </property>
-              </item>
-              <item>
-               <property name="text">
-                <string>+2</string>
-               </property>
-              </item>
-              <item>
-               <property name="text">
-                <string>+2a</string>
-               </property>
-              </item>
-              <item>
-               <property name="text">
-                <string>+3</string>
-               </property>
-              </item>
-             </widget>
-            </item>
-           </layout>
-          </item>
-          <item>
-           <spacer name="spectrumHSpacer">
-            <property name="orientation">
-             <enum>Qt::Horizontal</enum>
-            </property>
-            <property name="sizeHint" stdset="0">
-             <size>
-              <width>40</width>
-              <height>20</height>
-             </size>
-            </property>
-           </spacer>
-          </item>
-         </layout>
-        </item>
-       </layout>
-      </widget>
       <widget class="QWidget" name="vic20Tab">
        <attribute name="title">
         <string>Vic-20</string>
@@ -830,6 +893,75 @@
         </item>
        </layout>
       </widget>
+      <widget class="QWidget" name="spectrumTab">
+       <attribute name="title">
+        <string>ZX Spectrum</string>
+       </attribute>
+       <layout class="QVBoxLayout" name="spectrumLayout">
+        <item>
+         <layout class="QHBoxLayout" name="spectrumHorizontalLayout">
+          <item>
+           <layout class="QFormLayout" name="spectrumFormLayout">
+            <item row="0" column="0">
+             <widget class="QLabel" name="spectrumModelLabel">
+              <property name="text">
+               <string>Model:</string>
+              </property>
+             </widget>
+            </item>
+            <item row="0" column="1">
+             <widget class="QComboBox" name="spectrumModelComboBox">
+              <item>
+               <property name="text">
+                <string>16kb</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>48kb</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>128kb</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>+2</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>+2a</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>+3</string>
+               </property>
+              </item>
+             </widget>
+            </item>
+           </layout>
+          </item>
+          <item>
+           <spacer name="spectrumHSpacer">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+            <property name="sizeHint" stdset="0">
+             <size>
+              <width>40</width>
+              <height>20</height>
+             </size>
+            </property>
+           </spacer>
+          </item>
+         </layout>
+        </item>
+       </layout>
+      </widget>
      </widget>
     </item>
     <item alignment="Qt::AlignBottom">

From 1c424833a9ce1a356277f13b347d0caa989c2b16 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 29 Jun 2021 21:04:53 -0400
Subject: [PATCH 117/117] Correct EXDOS ROM name.

---
 Machines/Utility/ROMCatalogue.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Machines/Utility/ROMCatalogue.cpp b/Machines/Utility/ROMCatalogue.cpp
index acabcc591..99b2634bd 100644
--- a/Machines/Utility/ROMCatalogue.cpp
+++ b/Machines/Utility/ROMCatalogue.cpp
@@ -464,7 +464,7 @@ Description::Description(Name name) {
 		} break;
 		case Name::EnterpriseEXDOS: {
 			const std::initializer_list<std::string> filenames = {"exdos.bin", "EX-DOS EPROM (198x)(Enterprise).bin"};
-			*this = Description(name, "Enterprise", "the Enterprise EXOS ROM", filenames, 16 * 1024, 0xe6daa0e9u);
+			*this = Description(name, "Enterprise", "the Enterprise EXDOS ROM", filenames, 16 * 1024, 0xe6daa0e9u);
 		} break;
 
 		case Name::Macintosh128k:	*this = Description(name, "Macintosh", "the Macintosh 128k ROM", "mac128k.rom", 64*1024, 0x6d0c8a28u);	break;