diff --git a/Components/6560/6560.hpp b/Components/6560/6560.hpp
index 88ce2dbc2..829df3e7a 100644
--- a/Components/6560/6560.hpp
+++ b/Components/6560/6560.hpp
@@ -259,7 +259,7 @@ template <class T> class MOS6560 {
 				if(this_state_ != output_state_) {
 					switch(output_state_) {
 						case State::Sync:			crt_->output_sync(cycles_in_state_ * 4);														break;
-						case State::ColourBurst:	crt_->output_colour_burst(cycles_in_state_ * 4, (is_odd_frame_ || is_odd_line_) ? 128 : 0, 0);	break;
+						case State::ColourBurst:	crt_->output_colour_burst(cycles_in_state_ * 4, (is_odd_frame_ || is_odd_line_) ? 128 : 0);		break;
 						case State::Border:			output_border(cycles_in_state_ * 4);															break;
 						case State::Pixels:			crt_->output_data(cycles_in_state_ * 4, 1);														break;
 					}
diff --git a/Machines/ZX8081/ZX8081.cpp b/Machines/ZX8081/ZX8081.cpp
index 39bfdd862..b8bbae15a 100644
--- a/Machines/ZX8081/ZX8081.cpp
+++ b/Machines/ZX8081/ZX8081.cpp
@@ -23,7 +23,9 @@ Machine::Machine() :
 	nmi_is_enabled_(false),
 	tape_player_(ZX8081ClockRate),
 	use_fast_tape_hack_(false),
-	tape_advance_delay_(0) {
+	tape_advance_delay_(0),
+	tape_is_automatically_playing_(false),
+	tape_is_playing_(false) {
 	set_clock_rate(ZX8081ClockRate);
 	tape_player_.set_motor_control(true);
 	clear_all_keys();
@@ -55,7 +57,7 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
 
 	if(is_zx81_) horizontal_counter_ %= 207;
 	if(!tape_advance_delay_) {
-		tape_player_.run_for_cycles(cycle.length);
+		if(tape_is_automatically_playing_ || tape_is_playing_) tape_player_.run_for_cycles(cycle.length);
 	} else {
 		tape_advance_delay_ = std::max(tape_advance_delay_ - cycle.length, 0);
 	}
@@ -147,6 +149,9 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
 					tape_player_.get_tape()->seek(time);
 				}
 			}
+
+			// Check for automatic tape control.
+			tape_is_automatically_playing_ = use_automatic_tape_motor_control_ && (address >= automatic_tape_motor_start_address_) && (address < automatic_tape_motor_end_address_);
 			is_opcode_read = true;
 
 		case CPU::Z80::PartialMachineCycle::Read:
@@ -209,12 +214,16 @@ void Machine::configure_as_target(const StaticAnalyser::Target &target) {
 		tape_return_address_ = 0x380;
 		vsync_start_cycle_ = 16;
 		vsync_end_cycle_ = 32;
+		automatic_tape_motor_start_address_ = 0x0340;
+		automatic_tape_motor_end_address_ = 0x03c3;
 	} else {
 		rom_ = zx80_rom_;
 		tape_trap_address_ = 0x220;
 		tape_return_address_ = 0x248;
 		vsync_start_cycle_ = 13;
 		vsync_end_cycle_ = 33;
+		automatic_tape_motor_start_address_ = 0x0206;
+		automatic_tape_motor_end_address_ = 0x024d;
 	}
 	rom_mask_ = (uint16_t)(rom_.size() - 1);
 
diff --git a/Machines/ZX8081/ZX8081.hpp b/Machines/ZX8081/ZX8081.hpp
index d07ed461a..2d8ea8ba6 100644
--- a/Machines/ZX8081/ZX8081.hpp
+++ b/Machines/ZX8081/ZX8081.hpp
@@ -63,11 +63,18 @@ class Machine:
 		void clear_all_keys();
 
 		inline void set_use_fast_tape_hack(bool activate) { use_fast_tape_hack_ = activate; }
+		inline void set_use_automatic_tape_motor_control(bool enabled) {
+			use_automatic_tape_motor_control_ = enabled;
+			if(!enabled) tape_is_automatically_playing_ = false;
+		}
+		inline void set_tape_is_playing(bool is_playing) { tape_is_playing_ = is_playing; }
 
 	private:
 		std::shared_ptr<Video> video_;
 		std::vector<uint8_t> zx81_rom_, zx80_rom_;
+
 		uint16_t tape_trap_address_, tape_return_address_;
+		uint16_t automatic_tape_motor_start_address_, automatic_tape_motor_end_address_;
 
 		std::vector<uint8_t> ram_;
 		uint16_t ram_mask_, ram_base_;
@@ -94,6 +101,8 @@ class Machine:
 		uint8_t latched_video_byte_;
 
 		bool use_fast_tape_hack_;
+		bool use_automatic_tape_motor_control_;
+		bool tape_is_playing_, tape_is_automatically_playing_;
 		int tape_advance_delay_;
 };
 
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index 30bd9550c..35d3c1475 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -96,6 +96,7 @@
 		4B924E991E74D22700B76AF1 /* AtariStaticAnalyserTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4B924E981E74D22700B76AF1 /* AtariStaticAnalyserTests.mm */; };
 		4B9252CE1E74D28200B76AF1 /* Atari ROMs in Resources */ = {isa = PBXBuildFile; fileRef = 4B9252CD1E74D28200B76AF1 /* Atari ROMs */; };
 		4B92EACA1B7C112B00246143 /* 6502TimingTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B92EAC91B7C112B00246143 /* 6502TimingTests.swift */; };
+		4B95FA9D1F11893B0008E395 /* ZX8081OptionsPanel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B95FA9C1F11893B0008E395 /* ZX8081OptionsPanel.swift */; };
 		4B96F7221D75119A0058BB2D /* Tape.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B96F7201D75119A0058BB2D /* Tape.cpp */; };
 		4B9CCDA11DA279CA0098B625 /* Vic20OptionsPanel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B9CCDA01DA279CA0098B625 /* Vic20OptionsPanel.swift */; };
 		4BA0F68E1EEA0E8400E9489E /* ZX8081.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BA0F68C1EEA0E8400E9489E /* ZX8081.cpp */; };
@@ -609,6 +610,7 @@
 		4B924E981E74D22700B76AF1 /* AtariStaticAnalyserTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = AtariStaticAnalyserTests.mm; sourceTree = "<group>"; };
 		4B9252CD1E74D28200B76AF1 /* Atari ROMs */ = {isa = PBXFileReference; lastKnownFileType = folder; path = "Atari ROMs"; sourceTree = "<group>"; };
 		4B92EAC91B7C112B00246143 /* 6502TimingTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = 6502TimingTests.swift; sourceTree = "<group>"; };
+		4B95FA9C1F11893B0008E395 /* ZX8081OptionsPanel.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ZX8081OptionsPanel.swift; sourceTree = "<group>"; };
 		4B96F7201D75119A0058BB2D /* Tape.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = Tape.cpp; path = ../../StaticAnalyser/Acorn/Tape.cpp; sourceTree = "<group>"; };
 		4B96F7211D75119A0058BB2D /* Tape.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; name = Tape.hpp; path = ../../StaticAnalyser/Acorn/Tape.hpp; sourceTree = "<group>"; };
 		4B9CCDA01DA279CA0098B625 /* Vic20OptionsPanel.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Vic20OptionsPanel.swift; sourceTree = "<group>"; };
@@ -1312,6 +1314,7 @@
 				4B8FE2211DA19FB20090D3CE /* MachinePanel.swift */,
 				4B2A332E1DB86869002876E3 /* OricOptionsPanel.swift */,
 				4B9CCDA01DA279CA0098B625 /* Vic20OptionsPanel.swift */,
+				4B95FA9C1F11893B0008E395 /* ZX8081OptionsPanel.swift */,
 				4B8FE2131DA19D5F0090D3CE /* Atari2600Options.xib */,
 				4B8FE2171DA19D5F0090D3CE /* ElectronOptions.xib */,
 				4B8FE2151DA19D5F0090D3CE /* MachineDocument.xib */,
@@ -2566,6 +2569,7 @@
 				4BD4A8CD1E077E8A0020D856 /* PCMSegment.cpp in Sources */,
 				4BD14B111D74627C0088EAD6 /* StaticAnalyser.cpp in Sources */,
 				4BBF99151C8FBA6F0075DAFB /* CRTOpenGL.cpp in Sources */,
+				4B95FA9D1F11893B0008E395 /* ZX8081OptionsPanel.swift in Sources */,
 				4B0CCC451C62D0B3001CAC5F /* CRT.cpp in Sources */,
 				4BCF1FA41DADC3DD0039D2E7 /* Oric.cpp in Sources */,
 				4BEA525E1DF33323007E74F2 /* Tape.cpp in Sources */,
diff --git a/OSBindings/Mac/Clock Signal/Base.lproj/ZX8081Options.xib b/OSBindings/Mac/Clock Signal/Base.lproj/ZX8081Options.xib
index b1dcdf861..5b4b66fd0 100644
--- a/OSBindings/Mac/Clock Signal/Base.lproj/ZX8081Options.xib	
+++ b/OSBindings/Mac/Clock Signal/Base.lproj/ZX8081Options.xib	
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="12120" systemVersion="16F73" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none" useAutolayout="YES" customObjectInstantitationMethod="direct">
+<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="12121" systemVersion="16F73" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none" useAutolayout="YES" customObjectInstantitationMethod="direct">
     <dependencies>
-        <plugIn identifier="com.apple.InterfaceBuilder.CocoaPlugin" version="12120"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.CocoaPlugin" version="12121"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
     <objects>
@@ -12,17 +12,17 @@
         </customObject>
         <customObject id="-1" userLabel="First Responder" customClass="FirstResponder"/>
         <customObject id="-3" userLabel="Application" customClass="NSObject"/>
-        <window title="Options" allowsToolTipsWhenApplicationIsInactive="NO" autorecalculatesKeyViewLoop="NO" hidesOnDeactivate="YES" oneShot="NO" releasedWhenClosed="NO" showsToolbarButton="NO" visibleAtLaunch="NO" frameAutosaveName="" animationBehavior="default" id="ota-g7-hOL" customClass="MachinePanel" customModule="Clock_Signal" customModuleProvider="target">
+        <window title="Options" allowsToolTipsWhenApplicationIsInactive="NO" autorecalculatesKeyViewLoop="NO" hidesOnDeactivate="YES" oneShot="NO" releasedWhenClosed="NO" showsToolbarButton="NO" visibleAtLaunch="NO" frameAutosaveName="" animationBehavior="default" id="ota-g7-hOL" customClass="ZX8081OptionsPanel" customModule="Clock_Signal" customModuleProvider="target">
             <windowStyleMask key="styleMask" titled="YES" closable="YES" utility="YES" nonactivatingPanel="YES" HUD="YES"/>
             <windowPositionMask key="initialPositionMask" leftStrut="YES" rightStrut="YES" topStrut="YES" bottomStrut="YES"/>
-            <rect key="contentRect" x="83" y="102" width="200" height="54"/>
+            <rect key="contentRect" x="83" y="102" width="261" height="100"/>
             <rect key="screenRect" x="0.0" y="0.0" width="1366" height="768"/>
             <view key="contentView" id="7Pv-WL-2Rq">
-                <rect key="frame" x="0.0" y="0.0" width="200" height="54"/>
+                <rect key="frame" x="0.0" y="0.0" width="261" height="100"/>
                 <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                 <subviews>
                     <button translatesAutoresizingMaskIntoConstraints="NO" id="sBT-cU-h7s">
-                        <rect key="frame" x="18" y="18" width="164" height="18"/>
+                        <rect key="frame" x="18" y="64" width="225" height="18"/>
                         <buttonCell key="cell" type="check" title="Load Tapes Quickly" bezelStyle="regularSquare" imagePosition="left" alignment="left" state="on" inset="2" id="w0l-ha-esm">
                             <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
                             <font key="font" metaFont="system"/>
@@ -31,18 +31,46 @@
                             <action selector="setFastLoading:" target="ota-g7-hOL" id="me0-h2-Ga5"/>
                         </connections>
                     </button>
+                    <button translatesAutoresizingMaskIntoConstraints="NO" id="qSb-72-6Os">
+                        <rect key="frame" x="18" y="44" width="225" height="18"/>
+                        <buttonCell key="cell" type="check" title="Control Tape Motor Automatically" bezelStyle="regularSquare" imagePosition="left" state="on" inset="2" id="CzC-YT-lgA">
+                            <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
+                            <font key="font" metaFont="system"/>
+                        </buttonCell>
+                        <connections>
+                            <action selector="setAutomaticTapeMotorConrol:" target="ota-g7-hOL" id="bpF-1P-tga"/>
+                        </connections>
+                    </button>
+                    <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="tkN-gI-RmT">
+                        <rect key="frame" x="20" y="19" width="221" height="19"/>
+                        <buttonCell key="cell" type="roundRect" title="Play Tape" bezelStyle="roundedRect" alignment="center" enabled="NO" state="on" borderStyle="border" imageScaling="proportionallyDown" inset="2" id="cTq-f9-Gzx">
+                            <behavior key="behavior" pushIn="YES" lightByBackground="YES" lightByGray="YES"/>
+                            <font key="font" metaFont="cellTitle"/>
+                        </buttonCell>
+                        <connections>
+                            <action selector="playOrPauseTape:" target="ota-g7-hOL" id="O0K-pL-nOr"/>
+                        </connections>
+                    </button>
                 </subviews>
                 <constraints>
+                    <constraint firstItem="qSb-72-6Os" firstAttribute="leading" secondItem="7Pv-WL-2Rq" secondAttribute="leading" constant="20" id="05p-Jn-ueX"/>
                     <constraint firstAttribute="trailing" secondItem="sBT-cU-h7s" secondAttribute="trailing" constant="20" id="79b-2A-2c7"/>
                     <constraint firstItem="sBT-cU-h7s" firstAttribute="top" secondItem="7Pv-WL-2Rq" secondAttribute="top" constant="20" id="E5m-wo-X92"/>
-                    <constraint firstAttribute="bottom" secondItem="sBT-cU-h7s" secondAttribute="bottom" constant="20" id="eZe-Eu-INg"/>
+                    <constraint firstItem="qSb-72-6Os" firstAttribute="top" secondItem="sBT-cU-h7s" secondAttribute="bottom" constant="6" id="WxD-kP-vwf"/>
+                    <constraint firstAttribute="bottom" secondItem="tkN-gI-RmT" secondAttribute="bottom" constant="20" id="Xnu-On-nOA"/>
+                    <constraint firstItem="tkN-gI-RmT" firstAttribute="leading" secondItem="7Pv-WL-2Rq" secondAttribute="leading" constant="20" id="fHf-K0-PsU"/>
+                    <constraint firstItem="tkN-gI-RmT" firstAttribute="top" secondItem="qSb-72-6Os" secondAttribute="bottom" constant="8" id="gLh-vE-Cqk"/>
+                    <constraint firstAttribute="trailing" secondItem="qSb-72-6Os" secondAttribute="trailing" constant="20" id="mQz-p8-aYf"/>
                     <constraint firstItem="sBT-cU-h7s" firstAttribute="leading" secondItem="7Pv-WL-2Rq" secondAttribute="leading" constant="20" id="nDy-Xc-Ug9"/>
+                    <constraint firstAttribute="trailing" secondItem="tkN-gI-RmT" secondAttribute="trailing" constant="20" id="vgD-A3-m6T"/>
                 </constraints>
             </view>
             <connections>
+                <outlet property="automaticTapeMotorControlButton" destination="qSb-72-6Os" id="bB6-FP-TKM"/>
                 <outlet property="fastLoadingButton" destination="sBT-cU-h7s" id="uWa-EB-mbd"/>
+                <outlet property="playOrPauseTapeButton" destination="tkN-gI-RmT" id="UnJ-nb-3mv"/>
             </connections>
-            <point key="canvasLocation" x="-2" y="-8"/>
+            <point key="canvasLocation" x="28.5" y="15"/>
         </window>
     </objects>
 </document>
diff --git a/OSBindings/Mac/Clock Signal/ClockSignal-Bridging-Header.h b/OSBindings/Mac/Clock Signal/ClockSignal-Bridging-Header.h
index cd7a1da3a..e3c78f382 100644
--- a/OSBindings/Mac/Clock Signal/ClockSignal-Bridging-Header.h	
+++ b/OSBindings/Mac/Clock Signal/ClockSignal-Bridging-Header.h	
@@ -10,6 +10,7 @@
 #import "CSElectron.h"
 #import "CSOric.h"
 #import "CSVic20.h"
+#import "CSZX8081.h"
 
 #import "CSStaticAnalyser.h"
 
diff --git a/OSBindings/Mac/Clock Signal/Documents/ZX8081OptionsPanel.swift b/OSBindings/Mac/Clock Signal/Documents/ZX8081OptionsPanel.swift
new file mode 100644
index 000000000..541abfc84
--- /dev/null
+++ b/OSBindings/Mac/Clock Signal/Documents/ZX8081OptionsPanel.swift	
@@ -0,0 +1,49 @@
+//
+//  ZX8081OptionsPanel.swift
+//  Clock Signal
+//
+//  Created by Thomas Harte on 08/07/2017.
+//  Copyright © 2017 Thomas Harte. All rights reserved.
+//
+
+class ZX8081OptionsPanel: MachinePanel {
+	var zx8081: CSZX8081! {
+		get {
+			return self.machine as! CSZX8081
+		}
+	}
+
+	@IBOutlet var automaticTapeMotorControlButton: NSButton!
+	var automaticTapeMotorControlDefaultsKey: String {
+		get { return prefixedUserDefaultsKey("automaticTapeMotorControl") }
+	}
+	@IBAction func setAutomaticTapeMotorConrol(_ sender: NSButton!) {
+		let isEnabled = sender.state == NSOnState
+		UserDefaults.standard.set(isEnabled, forKey: self.automaticTapeMotorControlDefaultsKey)
+		self.playOrPauseTapeButton.isEnabled = !isEnabled
+		self.zx8081.useAutomaticTapeMotorControl = isEnabled
+	}
+
+	@IBOutlet var playOrPauseTapeButton: NSButton!
+	@IBAction func playOrPauseTape(_ sender: NSButton!) {
+		self.zx8081.tapeIsPlaying = !self.zx8081.tapeIsPlaying
+		self.playOrPauseTapeButton.title = self.zx8081.tapeIsPlaying
+			? NSLocalizedString("Stop Tape", comment: "Text for a button that will stop tape playback")
+			: NSLocalizedString("Play Tape", comment: "Text for a button that will start tape playback")
+	}
+
+	// MARK: option restoration
+	override func establishStoredOptions() {
+		super.establishStoredOptions()
+
+		let standardUserDefaults = UserDefaults.standard
+		standardUserDefaults.register(defaults: [
+			self.automaticTapeMotorControlDefaultsKey: true
+		])
+
+		let automaticTapeMotorControlIsEnabled = standardUserDefaults.bool(forKey: self.automaticTapeMotorControlDefaultsKey)
+		self.automaticTapeMotorControlButton.state = automaticTapeMotorControlIsEnabled ? NSOnState : NSOffState
+		self.playOrPauseTapeButton.isEnabled = !automaticTapeMotorControlIsEnabled
+		self.zx8081.useAutomaticTapeMotorControl = automaticTapeMotorControlIsEnabled
+	}
+}
diff --git a/OSBindings/Mac/Clock Signal/Machine/Wrappers/CSZX8081.h b/OSBindings/Mac/Clock Signal/Machine/Wrappers/CSZX8081.h
index 502bf21a8..3478e8c18 100644
--- a/OSBindings/Mac/Clock Signal/Machine/Wrappers/CSZX8081.h	
+++ b/OSBindings/Mac/Clock Signal/Machine/Wrappers/CSZX8081.h	
@@ -14,4 +14,7 @@
 
 @property (nonatomic, assign) BOOL useFastLoadingHack;
 
+@property (nonatomic, assign) BOOL useAutomaticTapeMotorControl;
+@property (nonatomic, assign) BOOL tapeIsPlaying;
+
 @end
diff --git a/OSBindings/Mac/Clock Signal/Machine/Wrappers/CSZX8081.mm b/OSBindings/Mac/Clock Signal/Machine/Wrappers/CSZX8081.mm
index d2abd2059..823cdf5bf 100644
--- a/OSBindings/Mac/Clock Signal/Machine/Wrappers/CSZX8081.mm	
+++ b/OSBindings/Mac/Clock Signal/Machine/Wrappers/CSZX8081.mm	
@@ -110,4 +110,18 @@
 	}
 }
 
+- (void)setTapeIsPlaying:(BOOL)tapeIsPlaying {
+	@synchronized(self) {
+		_tapeIsPlaying = tapeIsPlaying;
+		_zx8081.set_tape_is_playing(tapeIsPlaying ? true : false);
+	}
+}
+
+- (void)setUseAutomaticTapeMotorControl:(BOOL)useAutomaticTapeMotorControl {
+	@synchronized(self) {
+		_useAutomaticTapeMotorControl = useAutomaticTapeMotorControl;
+		_zx8081.set_use_automatic_tape_motor_control(useAutomaticTapeMotorControl ? true : false);
+	}
+}
+
 @end
diff --git a/Outputs/CRT/CRT.cpp b/Outputs/CRT/CRT.cpp
index c5ba7ee68..85be1eefa 100644
--- a/Outputs/CRT/CRT.cpp
+++ b/Outputs/CRT/CRT.cpp
@@ -8,9 +8,10 @@
 
 #include "CRT.hpp"
 #include "CRTOpenGL.hpp"
-#include <stdarg.h>
-#include <math.h>
+#include <cstdarg>
+#include <cmath>
 #include <algorithm>
+#include <cassert>
 
 using namespace Outputs::CRT;
 
@@ -144,6 +145,7 @@ void CRT::advance_cycles(unsigned int number_of_cycles, bool hsync_requested, bo
 
 		if(next_run) {
 			// output_y and texture locations will be written later; we won't necessarily know what it is outside of the locked region
+			openGL_output_builder_.texture_builder.retain_latest();
 			source_output_position_x1() = (uint16_t)horizontal_flywheel_->get_current_output_position();
 			source_phase() = colour_burst_phase_;
 			source_amplitude() = colour_burst_amplitude_;
@@ -192,9 +194,10 @@ void CRT::advance_cycles(unsigned int number_of_cycles, bool hsync_requested, bo
 						output_x2() = (uint16_t)horizontal_flywheel_->get_current_output_position();
 					}
 					openGL_output_builder_.array_builder.flush(
-						[output_y, this] (uint8_t *input_buffer, size_t input_size, uint8_t *output_buffer, size_t output_size) {
+						[=] (uint8_t *input_buffer, size_t input_size, uint8_t *output_buffer, size_t output_size) {
 							openGL_output_builder_.texture_builder.flush(
-								[output_y, input_buffer] (const std::vector<TextureBuilder::WriteArea> &write_areas, size_t number_of_write_areas) {
+								[=] (const std::vector<TextureBuilder::WriteArea> &write_areas, size_t number_of_write_areas) {
+									assert(number_of_write_areas * SourceVertexSize == input_size);
 									for(size_t run = 0; run < number_of_write_areas; run++) {
 										*(uint16_t *)&input_buffer[run * SourceVertexSize + SourceVertexOffsetOfInputStart + 0] = write_areas[run].x;
 										*(uint16_t *)&input_buffer[run * SourceVertexSize + SourceVertexOffsetOfInputStart + 2] = write_areas[run].y;
@@ -311,6 +314,7 @@ void CRT::output_blank(unsigned int number_of_cycles) {
 }
 
 void CRT::output_level(unsigned int number_of_cycles) {
+	openGL_output_builder_.texture_builder.reduce_previous_allocation_to(1);
 	Scan scan {
 		.type = Scan::Type::Level,
 		.number_of_cycles = number_of_cycles,
@@ -329,13 +333,7 @@ void CRT::output_colour_burst(unsigned int number_of_cycles, uint8_t phase, uint
 }
 
 void CRT::output_default_colour_burst(unsigned int number_of_cycles) {
-	Scan scan {
-		.type = Scan::Type::ColourBurst,
-		.number_of_cycles = number_of_cycles,
-		.phase = (uint8_t)((phase_numerator_ * 256) / phase_denominator_ + (is_alernate_line_ ? 128 : 0)),
-		.amplitude = 32
-	};
-	output_scan(&scan);
+	output_colour_burst(number_of_cycles, (uint8_t)((phase_numerator_ * 256) / phase_denominator_ + (is_alernate_line_ ? 128 : 0)));
 }
 
 void CRT::output_data(unsigned int number_of_cycles, unsigned int source_divider) {
diff --git a/Outputs/CRT/CRT.hpp b/Outputs/CRT/CRT.hpp
index 3f3847cf8..49f6bb206 100644
--- a/Outputs/CRT/CRT.hpp
+++ b/Outputs/CRT/CRT.hpp
@@ -187,7 +187,7 @@ class CRT {
 			@param amplitude The amplitude of the colour burst in 1/256ths of the amplitude of the
 			positive portion of the wave.
 		*/
-		void output_colour_burst(unsigned int number_of_cycles, uint8_t phase, uint8_t amplitude);
+		void output_colour_burst(unsigned int number_of_cycles, uint8_t phase, uint8_t amplitude = 102);
 
 		/*! Outputs a colour burst exactly in phase with CRT expectations using the idiomatic amplitude.
 
diff --git a/Outputs/CRT/Internals/TextureBuilder.cpp b/Outputs/CRT/Internals/TextureBuilder.cpp
index d36fbbf3c..98371bd4d 100644
--- a/Outputs/CRT/Internals/TextureBuilder.cpp
+++ b/Outputs/CRT/Internals/TextureBuilder.cpp
@@ -39,7 +39,6 @@ TextureBuilder::TextureBuilder(size_t bytes_per_pixel, GLenum texture_unit) :
 		write_areas_start_y_(0),
 		is_full_(false),
 		did_submit_(false),
-		has_write_area_(false),
 		number_of_write_areas_(0) {
 	image_.resize(bytes_per_pixel * InputBufferBuilderWidth * InputBufferBuilderHeight);
 	glGenTextures(1, &texture_name_);
@@ -74,7 +73,6 @@ uint8_t *TextureBuilder::allocate_write_area(size_t required_length) {
 		starting_y = write_areas_[number_of_write_areas_ - 1].y;
 	}
 
-	WriteArea next_write_area;
 	if(starting_x + required_length + 2 > InputBufferBuilderWidth) {
 		starting_x = 0;
 		starting_y++;
@@ -85,33 +83,34 @@ uint8_t *TextureBuilder::allocate_write_area(size_t required_length) {
 		}
 	}
 
-	next_write_area.x = starting_x + 1;
-	next_write_area.y = starting_y;
-	next_write_area.length = (uint16_t)required_length;
-	if(number_of_write_areas_ < write_areas_.size())
-		write_areas_[number_of_write_areas_] = next_write_area;
-	else
-		write_areas_.push_back(next_write_area);
-	number_of_write_areas_++;
-	has_write_area_ = true;
+	write_area_.x = starting_x + 1;
+	write_area_.y = starting_y;
+	write_area_.length = (uint16_t)required_length;
 
-	return pointer_to_location(next_write_area.x, next_write_area.y);
+	return pointer_to_location(write_area_.x, write_area_.y);
 }
 
 bool TextureBuilder::is_full() {
 	return is_full_;
 }
 
-void TextureBuilder::reduce_previous_allocation_to(size_t actual_length) {
-	if(is_full_ || !has_write_area_) return;
+void TextureBuilder::retain_latest() {
+	if(is_full_) return;
+	if(number_of_write_areas_ < write_areas_.size())
+		write_areas_[number_of_write_areas_] = write_area_;
+	else
+		write_areas_.push_back(write_area_);
+	number_of_write_areas_++;
+}
 
-	has_write_area_ = false;
-	WriteArea &write_area = write_areas_[number_of_write_areas_-1];
-	write_area.length = (uint16_t)actual_length;
+void TextureBuilder::reduce_previous_allocation_to(size_t actual_length) {
+	if(is_full_) return;
+
+	write_area_.length = (uint16_t)actual_length;
 
 	// book end the allocation with duplicates of the first and last pixel, to protect
 	// against rounding errors when this run is drawn
-	uint8_t *start_pointer = pointer_to_location(write_area.x, write_area.y);
+	uint8_t *start_pointer = pointer_to_location(write_area_.x, write_area_.y);
 	memcpy(	&start_pointer[-bytes_per_pixel_],
 			start_pointer,
 			bytes_per_pixel_);
@@ -172,6 +171,5 @@ void TextureBuilder::flush(const std::function<void(const std::vector<WriteArea>
 	}
 
 	did_submit_ = false;
-	has_write_area_ = false;
 	number_of_write_areas_ = 0;
 }
diff --git a/Outputs/CRT/Internals/TextureBuilder.hpp b/Outputs/CRT/Internals/TextureBuilder.hpp
index 93777ac92..88b95ee19 100644
--- a/Outputs/CRT/Internals/TextureBuilder.hpp
+++ b/Outputs/CRT/Internals/TextureBuilder.hpp
@@ -24,6 +24,32 @@ namespace CRT {
 	Owns an OpenGL texture resource and provides mechanisms to fill it from bottom left to top right
 	with runs of data, ensuring each run is neighboured immediately to the left and right by copies of its
 	first and last pixels.
+
+	Intended usage:
+
+		(i)		allocate a write area with allocate_write_area, supplying a maximum size.
+		(ii)	call reduce_previous_allocation_to to announce the actual size written.
+		
+	This will cause you to have added source data to the target texture. You can then either use that data
+	or allow it to expire.
+	
+		(iii)	call retain_latest to add the most recently written write area to the flush queue.
+
+	The flush queue contains provisional data, that can sit in the CPU's memory space indefinitely. This facility
+	is provided because it is expected that a texture will be built alontside some other collection of data —
+	that data in the flush queue is expected to become useful in coordination with something else but should
+	be retained at least until then.
+	
+		(iv)	call flush to move data to the submit queue.
+
+	When you flush, you'll receive a record of the bounds of all newly-flushed areas of source data. That gives
+	an opportunity to correlate the data with whatever else it is being tied to. It will continue to sit in
+	the CPU's memory space but has now passed beyond any further modification or reporting.
+
+		(v)		call submit to move data to the GPU and free up its CPU-side resources.
+
+	The data is now on the GPU, for whatever use the caller desires.
+
 */
 class TextureBuilder {
 	public:
@@ -41,6 +67,9 @@ class TextureBuilder {
 		/// and indicates that its actual final size was @c actual_length.
 		void reduce_previous_allocation_to(size_t actual_length);
 
+		/// Allocated runs are provisional; they will not appear in the next flush queue unless retained.
+		void retain_latest();
+
 		/// @returns @c true if all future calls to @c allocate_write_area will fail on account of the input texture
 		/// being full; @c false if calls may succeed.
 		bool is_full();
@@ -64,12 +93,14 @@ class TextureBuilder {
 		std::vector<uint8_t> image_;
 		GLuint texture_name_;
 
-		// the current list of write areas
+		// the current write area
+		WriteArea write_area_;
+
+		// the list of write areas that have ascended to the flush queue
 		std::vector<WriteArea> write_areas_;
 		size_t number_of_write_areas_;
 		bool is_full_;
 		bool did_submit_;
-		bool has_write_area_;
 		inline uint8_t *pointer_to_location(uint16_t x, uint16_t y);
 
 		// Usually: the start position for the current batch of write areas.
diff --git a/Storage/Tape/Formats/ZX80O81P.cpp b/Storage/Tape/Formats/ZX80O81P.cpp
index e1f969217..50a005260 100644
--- a/Storage/Tape/Formats/ZX80O81P.cpp
+++ b/Storage/Tape/Formats/ZX80O81P.cpp
@@ -54,7 +54,7 @@ Tape::Pulse ZX80O81P::virtual_get_next_pulse() {
 	// Start with 1 second of silence.
 	if(!is_past_silence_ || has_finished_data()) {
 		pulse.type = Pulse::Type::Low;
-		pulse.length.length = 10;
+		pulse.length.length = 1;
 		pulse.length.clock_rate = 1;
 		is_past_silence_ = true;
 		has_ended_final_byte_ = has_finished_data();