Merge pull request #758 from TomHarte/JasminDriveSelection

Switches Jasmin drive selection logic.

.github/workflows/ccpp.yml

@@ -0,0 +1,22 @@
+name: SDL/Ubuntu
+
+on:
+  push:
+    branches: 
+      - master
+
+  pull_request:
+    branches: 
+      - master
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    
+    steps:
+    - uses: actions/checkout@v1
+    - name: Install dependencies
+      run: sudo apt-get --allow-releaseinfo-change update; sudo apt-get install libsdl2-dev scons
+    - name: Make
+      run: cd OSBindings/SDL; scons

.travis.yml

@@ -1,13 +0,0 @@
-# language: objective-c
-# osx_image: xcode8.2
-# xcode_project: OSBindings/Mac/Clock Signal.xcodeproj
-# xcode_scheme: Clock Signal
-# xcode_sdk: macosx10.12
-
-language: cpp
-before_install:
-	- sudo apt-get install libsdl2-dev
-script: cd OSBindings/SDL && scons
-compiler:
-	- clang
-	- gcc

Analyser/Dynamic/ConfidenceCounter.hpp

@@ -22,7 +22,7 @@ namespace Dynamic {
 class ConfidenceCounter: public ConfidenceSource {
 	public:
 		/*! @returns The computed probability, based on the history of events. */
-		float get_confidence() override;
+		float get_confidence() final;
 
 		/*! Records an event that implies this is the appropriate class: pushes probability up towards 1.0. */
 		void add_hit();

Analyser/Dynamic/ConfidenceSummary.hpp

@@ -32,7 +32,7 @@ class ConfidenceSummary: public ConfidenceSource {
 			const std::vector<float> &weights);
 
 		/*! @returns The weighted sum of all sources. */
-		float get_confidence() override;
+		float get_confidence() final;
 
 	private:
 		std::vector<ConfidenceSource *> sources_;

Analyser/Dynamic/MultiMachine/Implementation/MultiCRTMachine.cpp

@@ -60,12 +60,19 @@ void MultiCRTMachine::set_scan_target(Outputs::Display::ScanTarget *scan_target)
 	if(crt_machine) crt_machine->set_scan_target(scan_target);
 }
 
+Outputs::Display::ScanStatus MultiCRTMachine::get_scan_status() const {
+	CRTMachine::Machine *const crt_machine = machines_.front()->crt_machine();
+	if(crt_machine) crt_machine->get_scan_status();
+
+	return Outputs::Display::ScanStatus();
+}
+
 Outputs::Speaker::Speaker *MultiCRTMachine::get_speaker() {
 	return speaker_;
 }
 
 void MultiCRTMachine::run_for(Time::Seconds duration) {
-	perform_parallel([=](::CRTMachine::Machine *machine) {
+	perform_parallel([duration](::CRTMachine::Machine *machine) {
 		if(machine->get_confidence() >= 0.01f) machine->run_for(duration);
 	});
 
@@ -75,7 +82,7 @@ void MultiCRTMachine::run_for(Time::Seconds duration) {
 void MultiCRTMachine::did_change_machine_order() {
 	if(scan_target_) scan_target_->will_change_owner();
 
-	perform_serial([=](::CRTMachine::Machine *machine) {
+	perform_serial([](::CRTMachine::Machine *machine) {
 		machine->set_scan_target(nullptr);
 	});
 	CRTMachine::Machine *const crt_machine = machines_.front()->crt_machine();

Analyser/Dynamic/MultiMachine/Implementation/MultiCRTMachine.hpp

@@ -53,12 +53,13 @@ class MultiCRTMachine: public CRTMachine::Machine {
 		}
 
 		// Below is the standard CRTMachine::Machine interface; see there for documentation.
-		void set_scan_target(Outputs::Display::ScanTarget *scan_target) override;
+		void set_scan_target(Outputs::Display::ScanTarget *scan_target) final;
-		Outputs::Speaker::Speaker *get_speaker() override;
+		Outputs::Display::ScanStatus get_scan_status() const final;
-		void run_for(Time::Seconds duration) override;
+		Outputs::Speaker::Speaker *get_speaker() final;
+		void run_for(Time::Seconds duration) final;
 
 	private:
-		void run_for(const Cycles cycles) override {}
+		void run_for(const Cycles cycles) final {}
 		const std::vector<std::unique_ptr<::Machine::DynamicMachine>> &machines_;
 		std::recursive_mutex &machines_mutex_;
 		std::vector<Concurrency::AsyncTaskQueue> queues_;

Analyser/Dynamic/MultiMachine/Implementation/MultiConfigurable.hpp

@@ -28,10 +28,10 @@ class MultiConfigurable: public Configurable::Device {
 		MultiConfigurable(const std::vector<std::unique_ptr<::Machine::DynamicMachine>> &machines);
 
 		// Below is the standard Configurable::Device interface; see there for documentation.
-		std::vector<std::unique_ptr<Configurable::Option>> get_options() override;
+		std::vector<std::unique_ptr<Configurable::Option>> get_options() final;
-		void set_selections(const Configurable::SelectionSet &selection_by_option) override;
+		void set_selections(const Configurable::SelectionSet &selection_by_option) final;
-		Configurable::SelectionSet get_accurate_selections() override;
+		Configurable::SelectionSet get_accurate_selections() final;
-		Configurable::SelectionSet get_user_friendly_selections() override;
+		Configurable::SelectionSet get_user_friendly_selections() final;
 
 	private:
 		std::vector<Configurable::Device *> devices_;

Analyser/Dynamic/MultiMachine/Implementation/MultiJoystickMachine.cpp

@@ -25,7 +25,7 @@ class MultiJoystick: public Inputs::Joystick {
 			}
 		}
 
-		std::vector<Input> &get_inputs() override {
+		std::vector<Input> &get_inputs() final {
 			if(inputs.empty()) {
 				for(const auto &joystick: joysticks_) {
 					std::vector<Input> joystick_inputs = joystick->get_inputs();
@@ -40,19 +40,19 @@ class MultiJoystick: public Inputs::Joystick {
 			return inputs;
 		}
 
-		void set_input(const Input &digital_input, bool is_active) override {
+		void set_input(const Input &digital_input, bool is_active) final {
 			for(const auto &joystick: joysticks_) {
 				joystick->set_input(digital_input, is_active);
 			}
 		}
 
-		void set_input(const Input &digital_input, float value) override {
+		void set_input(const Input &digital_input, float value) final {
 			for(const auto &joystick: joysticks_) {
 				joystick->set_input(digital_input, value);
 			}
 		}
 
-		void reset_all_inputs() override {
+		void reset_all_inputs() final {
 			for(const auto &joystick: joysticks_) {
 				joystick->reset_all_inputs();
 			}
@@ -81,6 +81,6 @@ MultiJoystickMachine::MultiJoystickMachine(const std::vector<std::unique_ptr<::M
 	}
 }
 
-std::vector<std::unique_ptr<Inputs::Joystick>> &MultiJoystickMachine::get_joysticks() {
+const std::vector<std::unique_ptr<Inputs::Joystick>> &MultiJoystickMachine::get_joysticks() {
 	return joysticks_;
 }

Analyser/Dynamic/MultiMachine/Implementation/MultiJoystickMachine.hpp

@@ -28,7 +28,7 @@ class MultiJoystickMachine: public JoystickMachine::Machine {
 		MultiJoystickMachine(const std::vector<std::unique_ptr<::Machine::DynamicMachine>> &machines);
 
 		// Below is the standard JoystickMachine::Machine interface; see there for documentation.
-		std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() override;
+		const std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() final;
 
 	private:
 		std::vector<std::unique_ptr<Inputs::Joystick>> joysticks_;

Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.hpp

@@ -32,10 +32,10 @@ class MultiKeyboardMachine: public KeyboardMachine::Machine {
 			public:
 				MultiKeyboard(const std::vector<::KeyboardMachine::Machine *> &machines);
 
-				void set_key_pressed(Key key, char value, bool is_pressed) override;
+				void set_key_pressed(Key key, char value, bool is_pressed) final;
-				void reset_all_keys() override;
+				void reset_all_keys() final;
-				const std::set<Key> &observed_keys() override;
+				const std::set<Key> &observed_keys() final;
-				bool is_exclusive() override;
+				bool is_exclusive() final;
 
 			private:
 				const std::vector<::KeyboardMachine::Machine *> &machines_;
@@ -48,10 +48,10 @@ class MultiKeyboardMachine: public KeyboardMachine::Machine {
 		MultiKeyboardMachine(const std::vector<std::unique_ptr<::Machine::DynamicMachine>> &machines);
 
 		// Below is the standard KeyboardMachine::Machine interface; see there for documentation.
-		void clear_all_keys() override;
+		void clear_all_keys() final;
-		void set_key_state(uint16_t key, bool is_pressed) override;
+		void set_key_state(uint16_t key, bool is_pressed) final;
-		void type_string(const std::string &) override;
+		void type_string(const std::string &) final;
-		Inputs::Keyboard &get_keyboard() override;
+		Inputs::Keyboard &get_keyboard() final;
 };
 
 }

Analyser/Dynamic/MultiMachine/Implementation/MultiMediaTarget.hpp

@@ -29,7 +29,7 @@ struct MultiMediaTarget: public MediaTarget::Machine {
 		MultiMediaTarget(const std::vector<std::unique_ptr<::Machine::DynamicMachine>> &machines);
 
 		// Below is the standard MediaTarget::Machine interface; see there for documentation.
-		bool insert_media(const Analyser::Static::Media &media) override;
+		bool insert_media(const Analyser::Static::Media &media) final;
 
 	private:
 		std::vector<MediaTarget::Machine *> targets_;

Analyser/Dynamic/MultiMachine/Implementation/MultiSpeaker.cpp

@@ -37,12 +37,23 @@ float MultiSpeaker::get_ideal_clock_rate_in_range(float minimum, float maximum)
 	return ideal / static_cast<float>(speakers_.size());
 }
 
-void MultiSpeaker::set_output_rate(float cycles_per_second, int buffer_size) {
+void MultiSpeaker::set_computed_output_rate(float cycles_per_second, int buffer_size, bool stereo) {
+	stereo_output_ = stereo;
 	for(const auto &speaker: speakers_) {
-		speaker->set_output_rate(cycles_per_second, buffer_size);
+		speaker->set_computed_output_rate(cycles_per_second, buffer_size, stereo);
 	}
 }
 
+bool MultiSpeaker::get_is_stereo() {
+	// Return as stereo if any subspeaker is stereo.
+	for(const auto &speaker: speakers_) {
+		if(speaker->get_is_stereo()) {
+			return true;
+		}
+	}
+	return false;
+}
+
 void MultiSpeaker::set_delegate(Outputs::Speaker::Speaker::Delegate *delegate) {
 	delegate_ = delegate;
 }
@@ -53,7 +64,7 @@ void MultiSpeaker::speaker_did_complete_samples(Speaker *speaker, const std::vec
 		std::lock_guard<std::mutex> lock_guard(front_speaker_mutex_);
 		if(speaker != front_speaker_) return;
 	}
-	delegate_->speaker_did_complete_samples(this, buffer);
+	did_complete_samples(this, buffer, stereo_output_);
 }
 
 void MultiSpeaker::speaker_did_change_input_clock(Speaker *speaker) {

Analyser/Dynamic/MultiMachine/Implementation/MultiSpeaker.hpp

@@ -39,18 +39,21 @@ class MultiSpeaker: public Outputs::Speaker::Speaker, Outputs::Speaker::Speaker:
 
 		// Below is the standard Outputs::Speaker::Speaker interface; see there for documentation.
 		float get_ideal_clock_rate_in_range(float minimum, float maximum) override;
-		void set_output_rate(float cycles_per_second, int buffer_size) override;
+		void set_computed_output_rate(float cycles_per_second, int buffer_size, bool stereo) override;
 		void set_delegate(Outputs::Speaker::Speaker::Delegate *delegate) override;
+		bool get_is_stereo() override;
 
 	private:
-		void speaker_did_complete_samples(Speaker *speaker, const std::vector<int16_t> &buffer) override;
+		void speaker_did_complete_samples(Speaker *speaker, const std::vector<int16_t> &buffer) final;
-		void speaker_did_change_input_clock(Speaker *speaker) override;
+		void speaker_did_change_input_clock(Speaker *speaker) final;
 		MultiSpeaker(const std::vector<Outputs::Speaker::Speaker *> &speakers);
 
 		std::vector<Outputs::Speaker::Speaker *> speakers_;
 		Outputs::Speaker::Speaker *front_speaker_ = nullptr;
 		Outputs::Speaker::Speaker::Delegate *delegate_ = nullptr;
 		std::mutex front_speaker_mutex_;
+
+		bool stereo_output_ = false;
 };
 
 }

Analyser/Dynamic/MultiMachine/MultiMachine.hpp

@@ -50,17 +50,17 @@ class MultiMachine: public ::Machine::DynamicMachine, public MultiCRTMachine::De
 		static bool would_collapse(const std::vector<std::unique_ptr<DynamicMachine>> &machines);
 		MultiMachine(std::vector<std::unique_ptr<DynamicMachine>> &&machines);
 
-		Activity::Source *activity_source() override;
+		Activity::Source *activity_source() final;
-		Configurable::Device *configurable_device() override;
+		Configurable::Device *configurable_device() final;
-		CRTMachine::Machine *crt_machine() override;
+		CRTMachine::Machine *crt_machine() final;
-		JoystickMachine::Machine *joystick_machine() override;
+		JoystickMachine::Machine *joystick_machine() final;
-		MouseMachine::Machine *mouse_machine() override;
+		MouseMachine::Machine *mouse_machine() final;
-		KeyboardMachine::Machine *keyboard_machine() override;
+		KeyboardMachine::Machine *keyboard_machine() final;
-		MediaTarget::Machine *media_target() override;
+		MediaTarget::Machine *media_target() final;
-		void *raw_pointer() override;
+		void *raw_pointer() final;
 
 	private:
-		void multi_crt_did_run_machines() override;
+		void multi_crt_did_run_machines() final;
 
 		std::vector<std::unique_ptr<DynamicMachine>> machines_;
 		std::recursive_mutex machines_mutex_;

Analyser/Machines.hpp

@@ -15,6 +15,7 @@ enum class Machine {
 	AmstradCPC,
 	AppleII,
 	Atari2600,
+	AtariST,
 	ColecoVision,
 	Electron,
 	Macintosh,

Analyser/Static/Acorn/Disk.cpp

@@ -10,7 +10,7 @@
 
 #include "../../../Storage/Disk/Controller/DiskController.hpp"
 #include "../../../Storage/Disk/Encodings/MFM/Parser.hpp"
-#include "../../../NumberTheory/CRC.hpp"
+#include "../../../Numeric/CRC.hpp"
 
 #include <algorithm>
 
@@ -18,7 +18,7 @@ using namespace Analyser::Static::Acorn;
 
 std::unique_ptr<Catalogue> Analyser::Static::Acorn::GetDFSCatalogue(const std::shared_ptr<Storage::Disk::Disk> &disk) {
 	// c.f. http://beebwiki.mdfs.net/Acorn_DFS_disc_format
-	std::unique_ptr<Catalogue> catalogue(new Catalogue);
+	auto catalogue = std::make_unique<Catalogue>();
 	Storage::Encodings::MFM::Parser parser(false, disk);
 
 	Storage::Encodings::MFM::Sector *names = parser.get_sector(0, 0, 0);
@@ -75,7 +75,7 @@ std::unique_ptr<Catalogue> Analyser::Static::Acorn::GetDFSCatalogue(const std::s
 	return catalogue;
 }
 std::unique_ptr<Catalogue> Analyser::Static::Acorn::GetADFSCatalogue(const std::shared_ptr<Storage::Disk::Disk> &disk) {
-	std::unique_ptr<Catalogue> catalogue(new Catalogue);
+	auto catalogue = std::make_unique<Catalogue>();
 	Storage::Encodings::MFM::Parser parser(true, disk);
 
 	Storage::Encodings::MFM::Sector *free_space_map_second_half = parser.get_sector(0, 0, 1);

Analyser/Static/Acorn/StaticAnalyser.cpp

@@ -58,7 +58,7 @@ static std::vector<std::shared_ptr<Storage::Cartridge::Cartridge>>
 }
 
 Analyser::Static::TargetList Analyser::Static::Acorn::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
-	std::unique_ptr<Target> target(new Target);
+	auto target = std::make_unique<Target>();
 	target->machine = Machine::Electron;
 	target->confidence = 0.5; // TODO: a proper estimation
 	target->has_dfs = false;

Analyser/Static/Acorn/Tape.cpp

@@ -10,13 +10,13 @@
 
 #include <deque>
 
-#include "../../../NumberTheory/CRC.hpp"
+#include "../../../Numeric/CRC.hpp"
 #include "../../../Storage/Tape/Parsers/Acorn.hpp"
 
 using namespace Analyser::Static::Acorn;
 
 static std::unique_ptr<File::Chunk> GetNextChunk(const std::shared_ptr<Storage::Tape::Tape> &tape, Storage::Tape::Acorn::Parser &parser) {
-	std::unique_ptr<File::Chunk> new_chunk(new File::Chunk);
+	auto new_chunk = std::make_unique<File::Chunk>();
 	int shift_register = 0;
 
 // TODO: move this into the parser
@@ -90,7 +90,7 @@ static std::unique_ptr<File> GetNextFile(std::deque<File::Chunk> &chunks) {
 	if(!chunks.size()) return nullptr;
 
 	// accumulate chunks for as long as block number is sequential and the end-of-file bit isn't set
-	std::unique_ptr<File> file(new File);
+	auto file = std::make_unique<File>();
 
 	uint16_t block_number = 0;
 

Analyser/Static/AmstradCPC/StaticAnalyser.cpp

@@ -181,7 +181,7 @@ static bool CheckBootSector(const std::shared_ptr<Storage::Disk::Disk> &disk, co
 
 Analyser::Static::TargetList Analyser::Static::AmstradCPC::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
 	TargetList destination;
-	std::unique_ptr<Target> target(new Target);
+	auto target = std::make_unique<Target>();
 	target->machine = Machine::AmstradCPC;
 	target->confidence = 0.5;
 

Analyser/Static/AppleII/StaticAnalyser.cpp

@@ -10,7 +10,7 @@
 #include "Target.hpp"
 
 Analyser::Static::TargetList Analyser::Static::AppleII::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
-	auto target = std::unique_ptr<Target>(new Target);
+	auto target = std::make_unique<Target>();
 	target->machine = Machine::AppleII;
 	target->media = media;
 

Analyser/Static/Atari2600/StaticAnalyser.cpp

@@ -12,9 +12,10 @@
 
 #include "../Disassembler/6502.hpp"
 
-using namespace Analyser::Static::Atari;
+using namespace Analyser::Static::Atari2600;
+using Target = Analyser::Static::Atari2600::Target;
 
-static void DeterminePagingFor2kCartridge(Analyser::Static::Atari::Target &target, const Storage::Cartridge::Cartridge::Segment &segment) {
+static void DeterminePagingFor2kCartridge(Target &target, const Storage::Cartridge::Cartridge::Segment &segment) {
 	// if this is a 2kb cartridge then it's definitely either unpaged or a CommaVid
 	uint16_t entry_address, break_address;
 
@@ -48,10 +49,10 @@ static void DeterminePagingFor2kCartridge(Analyser::Static::Atari::Target &targe
 	// caveat: false positives aren't likely to be problematic; a false positive is a 2KB ROM that always addresses
 	// itself so as to land in ROM even if mapped as a CommaVid and this code is on the fence as to whether it
 	// attempts to modify itself but it probably doesn't
-	if(has_wide_area_store) target.paging_model = Analyser::Static::Atari::Target::PagingModel::CommaVid;
+	if(has_wide_area_store) target.paging_model = Target::PagingModel::CommaVid;
 }
 
-static void DeterminePagingFor8kCartridge(Analyser::Static::Atari::Target &target, const Storage::Cartridge::Cartridge::Segment &segment, const Analyser::Static::MOS6502::Disassembly &disassembly) {
+static void DeterminePagingFor8kCartridge(Target &target, const Storage::Cartridge::Cartridge::Segment &segment, const Analyser::Static::MOS6502::Disassembly &disassembly) {
 	// Activision stack titles have their vectors at the top of the low 4k, not the top, and
 	// always list 0xf000 as both vectors; they do not repeat them, and, inexplicably, they all
 	// issue an SEI as their first instruction (maybe some sort of relic of the development environment?)
@@ -60,12 +61,12 @@ static void DeterminePagingFor8kCartridge(Analyser::Static::Atari::Target &targe
 		(segment.data[8191] != 0xf0 || segment.data[8189] != 0xf0 || segment.data[8190] != 0x00 || segment.data[8188] != 0x00) &&
 		segment.data[0] == 0x78
 	) {
-		target.paging_model = Analyser::Static::Atari::Target::PagingModel::ActivisionStack;
+		target.paging_model = Target::PagingModel::ActivisionStack;
 		return;
 	}
 
 	// make an assumption that this is the Atari paging model
-	target.paging_model = Analyser::Static::Atari::Target::PagingModel::Atari8k;
+	target.paging_model = Target::PagingModel::Atari8k;
 
 	std::set<uint16_t> internal_accesses;
 	internal_accesses.insert(disassembly.internal_stores.begin(), disassembly.internal_stores.end());
@@ -85,13 +86,13 @@ static void DeterminePagingFor8kCartridge(Analyser::Static::Atari::Target &targe
 		tigervision_access_count += masked_address == 0x3f;
 	}
 
-	if(parker_access_count > atari_access_count) target.paging_model = Analyser::Static::Atari::Target::PagingModel::ParkerBros;
+	if(parker_access_count > atari_access_count) target.paging_model = Target::PagingModel::ParkerBros;
-	else if(tigervision_access_count > atari_access_count) target.paging_model = Analyser::Static::Atari::Target::PagingModel::Tigervision;
+	else if(tigervision_access_count > atari_access_count) target.paging_model = Target::PagingModel::Tigervision;
 }
 
-static void DeterminePagingFor16kCartridge(Analyser::Static::Atari::Target &target, const Storage::Cartridge::Cartridge::Segment &segment, const Analyser::Static::MOS6502::Disassembly &disassembly) {
+static void DeterminePagingFor16kCartridge(Target &target, const Storage::Cartridge::Cartridge::Segment &segment, const Analyser::Static::MOS6502::Disassembly &disassembly) {
 	// make an assumption that this is the Atari paging model
-	target.paging_model = Analyser::Static::Atari::Target::PagingModel::Atari16k;
+	target.paging_model = Target::PagingModel::Atari16k;
 
 	std::set<uint16_t> internal_accesses;
 	internal_accesses.insert(disassembly.internal_stores.begin(), disassembly.internal_stores.end());
@@ -106,17 +107,17 @@ static void DeterminePagingFor16kCartridge(Analyser::Static::Atari::Target &targ
 		mnetwork_access_count += masked_address >= 0x1fe0 && masked_address < 0x1ffb;
 	}
 
-	if(mnetwork_access_count > atari_access_count) target.paging_model = Analyser::Static::Atari::Target::PagingModel::MNetwork;
+	if(mnetwork_access_count > atari_access_count) target.paging_model = Target::PagingModel::MNetwork;
 }
 
-static void DeterminePagingFor64kCartridge(Analyser::Static::Atari::Target &target, const Storage::Cartridge::Cartridge::Segment &segment, const Analyser::Static::MOS6502::Disassembly &disassembly) {
+static void DeterminePagingFor64kCartridge(Target &target, const Storage::Cartridge::Cartridge::Segment &segment, const Analyser::Static::MOS6502::Disassembly &disassembly) {
 	// make an assumption that this is a Tigervision if there is a write to 3F
 	target.paging_model =
 		(disassembly.external_stores.find(0x3f) != disassembly.external_stores.end()) ?
-			Analyser::Static::Atari::Target::PagingModel::Tigervision : Analyser::Static::Atari::Target::PagingModel::MegaBoy;
+			Target::PagingModel::Tigervision : Target::PagingModel::MegaBoy;
 }
 
-static void DeterminePagingForCartridge(Analyser::Static::Atari::Target &target, const Storage::Cartridge::Cartridge::Segment &segment) {
+static void DeterminePagingForCartridge(Target &target, const Storage::Cartridge::Cartridge::Segment &segment) {
 	if(segment.data.size() == 2048) {
 		DeterminePagingFor2kCartridge(target, segment);
 		return;
@@ -140,16 +141,16 @@ static void DeterminePagingForCartridge(Analyser::Static::Atari::Target &target,
 			DeterminePagingFor8kCartridge(target, segment, disassembly);
 		break;
 		case 10495:
-			target.paging_model = Analyser::Static::Atari::Target::PagingModel::Pitfall2;
+			target.paging_model = Target::PagingModel::Pitfall2;
 		break;
 		case 12288:
-			target.paging_model = Analyser::Static::Atari::Target::PagingModel::CBSRamPlus;
+			target.paging_model = Target::PagingModel::CBSRamPlus;
 		break;
 		case 16384:
 			DeterminePagingFor16kCartridge(target, segment, disassembly);
 		break;
 		case 32768:
-			target.paging_model = Analyser::Static::Atari::Target::PagingModel::Atari32k;
+			target.paging_model = Target::PagingModel::Atari32k;
 		break;
 		case 65536:
 			DeterminePagingFor64kCartridge(target, segment, disassembly);
@@ -161,8 +162,8 @@ static void DeterminePagingForCartridge(Analyser::Static::Atari::Target &target,
 	// check for a Super Chip. Atari ROM images [almost] always have the same value stored over RAM
 	// regions; when they don't they at least seem to have the first 128 bytes be the same as the
 	// next 128 bytes. So check for that.
-	if(	target.paging_model != Analyser::Static::Atari::Target::PagingModel::CBSRamPlus &&
+	if(	target.paging_model != Target::PagingModel::CBSRamPlus &&
-		target.paging_model != Analyser::Static::Atari::Target::PagingModel::MNetwork) {
+		target.paging_model != Target::PagingModel::MNetwork) {
 		bool has_superchip = true;
 		for(std::size_t address = 0; address < 128; address++) {
 			if(segment.data[address] != segment.data[address+128]) {
@@ -174,19 +175,19 @@ static void DeterminePagingForCartridge(Analyser::Static::Atari::Target &target,
 	}
 
 	// check for a Tigervision or Tigervision-esque scheme
-	if(target.paging_model == Analyser::Static::Atari::Target::PagingModel::None && segment.data.size() > 4096) {
+	if(target.paging_model == Target::PagingModel::None && segment.data.size() > 4096) {
 		bool looks_like_tigervision = disassembly.external_stores.find(0x3f) != disassembly.external_stores.end();
-		if(looks_like_tigervision) target.paging_model = Analyser::Static::Atari::Target::PagingModel::Tigervision;
+		if(looks_like_tigervision) target.paging_model = Target::PagingModel::Tigervision;
 	}
 }
 
-Analyser::Static::TargetList Analyser::Static::Atari::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
+Analyser::Static::TargetList Analyser::Static::Atari2600::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
 	// TODO: sanity checking; is this image really for an Atari 2600?
-	std::unique_ptr<Analyser::Static::Atari::Target> target(new Analyser::Static::Atari::Target);
+	auto target = std::make_unique<Target>();
 	target->machine = Machine::Atari2600;
 	target->confidence = 0.5;
 	target->media.cartridges = media.cartridges;
-	target->paging_model = Analyser::Static::Atari::Target::PagingModel::None;
+	target->paging_model = Target::PagingModel::None;
 	target->uses_superchip = false;
 
 	// try to figure out the paging scheme

Analyser/Static/Atari2600/StaticAnalyser.hpp

@@ -15,7 +15,7 @@
 
 namespace Analyser {
 namespace Static {
-namespace Atari {
+namespace Atari2600 {
 
 TargetList GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms);
 

Analyser/Static/Atari2600/Target.hpp

@@ -6,14 +6,14 @@
 //  Copyright 2018 Thomas Harte. All rights reserved.
 //
 
-#ifndef Analyser_Static_Atari_Target_h
+#ifndef Analyser_Static_Atari2600_Target_h
-#define Analyser_Static_Atari_Target_h
+#define Analyser_Static_Atari2600_Target_h
 
 #include "../StaticAnalyser.hpp"
 
 namespace Analyser {
 namespace Static {
-namespace Atari {
+namespace Atari2600 {
 
 struct Target: public ::Analyser::Static::Target {
 	enum class PagingModel {

Analyser/Static/AtariST/StaticAnalyser.cpp

@@ -0,0 +1,26 @@
+//
+//  StaticAnalyser.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 03/10/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#include "StaticAnalyser.hpp"
+#include "Target.hpp"
+
+Analyser::Static::TargetList Analyser::Static::AtariST::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
+	// This analyser can comprehend disks and mass-storage devices only.
+	if(media.disks.empty()) return {};
+
+	// As there is at least one usable media image, wave it through.
+	Analyser::Static::TargetList targets;
+
+	using Target = Analyser::Static::Target;
+	auto *target = new Target;
+	target->machine = Analyser::Machine::AtariST;
+	target->media = media;
+	targets.push_back(std::unique_ptr<Analyser::Static::Target>(target));
+
+	return targets;
+}

Analyser/Static/AtariST/StaticAnalyser.hpp

@@ -0,0 +1,27 @@
+//
+//  StaticAnalyser.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 03/10/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#ifndef Analyser_Static_AtariST_StaticAnalyser_hpp
+#define Analyser_Static_AtariST_StaticAnalyser_hpp
+
+#include "../StaticAnalyser.hpp"
+#include "../../../Storage/TargetPlatforms.hpp"
+#include <string>
+
+namespace Analyser {
+namespace Static {
+namespace AtariST {
+
+TargetList GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms);
+
+}
+}
+}
+
+
+#endif /* Analyser_Static_AtariST_StaticAnalyser_hpp */

Analyser/Static/AtariST/Target.hpp

@@ -0,0 +1,23 @@
+//
+//  Target.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 03/06/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#ifndef Analyser_Static_AtariST_Target_h
+#define Analyser_Static_AtariST_Target_h
+
+namespace Analyser {
+namespace Static {
+namespace AtariST {
+
+struct Target: public ::Analyser::Static::Target {
+};
+
+}
+}
+}
+
+#endif /* Analyser_Static_AtariST_Target_h */

Analyser/Static/Coleco/StaticAnalyser.cpp

@@ -54,7 +54,7 @@ static std::vector<std::shared_ptr<Storage::Cartridge::Cartridge>>
 
 Analyser::Static::TargetList Analyser::Static::Coleco::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
 	TargetList targets;
-	std::unique_ptr<Target> target(new Target);
+	auto target = std::make_unique<Target>();
 	target->machine = Machine::ColecoVision;
 	target->confidence = 1.0f - 1.0f / 32768.0f;
 	target->media.cartridges = ColecoCartridgesFrom(media.cartridges);

Analyser/Static/Commodore/Disk.cpp

@@ -19,12 +19,10 @@ using namespace Analyser::Static::Commodore;
 
 class CommodoreGCRParser: public Storage::Disk::Controller {
 	public:
-		std::shared_ptr<Storage::Disk::Drive> drive;
-
 		CommodoreGCRParser() : Storage::Disk::Controller(4000000), shift_register_(0), track_(1) {
-			drive.reset(new Storage::Disk::Drive(4000000, 300, 2));
+			emplace_drive(4000000, 300, 2);
-			set_drive(drive);
+			set_drive(1);
-			drive->set_motor_on(true);
+			get_drive().set_motor_on(true);
 		}
 
 		struct Sector {
@@ -61,6 +59,10 @@ class CommodoreGCRParser: public Storage::Disk::Controller {
 			return get_sector(sector);
 		}
 
+		void set_disk(const std::shared_ptr<Storage::Disk::Disk> &disk) {
+			get_drive().set_disk(disk);
+		}
+
 	private:
 		unsigned int shift_register_;
 		int index_count_;
@@ -125,7 +127,7 @@ class CommodoreGCRParser: public Storage::Disk::Controller {
 		}
 
 		std::shared_ptr<Sector> get_next_sector() {
-			std::shared_ptr<Sector> sector(new Sector);
+			auto sector = std::make_shared<Sector>();
 			const int max_index_count = index_count_ + 2;
 
 			while(index_count_ < max_index_count) {
@@ -170,7 +172,7 @@ class CommodoreGCRParser: public Storage::Disk::Controller {
 std::vector<File> Analyser::Static::Commodore::GetFiles(const std::shared_ptr<Storage::Disk::Disk> &disk) {
 	std::vector<File> files;
 	CommodoreGCRParser parser;
-	parser.drive->set_disk(disk);
+	parser.set_disk(disk);
 
 	// find any sector whatsoever to establish the current track
 	std::shared_ptr<CommodoreGCRParser::Sector> sector;

Analyser/Static/Commodore/StaticAnalyser.cpp

@@ -16,6 +16,7 @@
 #include "../../../Outputs/Log.hpp"
 
 #include <algorithm>
+#include <cstring>
 #include <sstream>
 
 using namespace Analyser::Static::Commodore;
@@ -44,7 +45,7 @@ static std::vector<std::shared_ptr<Storage::Cartridge::Cartridge>>
 Analyser::Static::TargetList Analyser::Static::Commodore::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
 	TargetList destination;
 
-	std::unique_ptr<Target> target(new Target);
+	auto target = std::make_unique<Target>();
 	target->machine = Machine::Vic20;	// TODO: machine estimation
 	target->confidence = 0.5; // TODO: a proper estimation
 
@@ -78,7 +79,7 @@ Analyser::Static::TargetList Analyser::Static::Commodore::GetTargets(const Media
 	}
 
 	if(!files.empty()) {
-		target->memory_model = Target::MemoryModel::Unexpanded;
+		auto memory_model = Target::MemoryModel::Unexpanded;
 		std::ostringstream string_stream;
 		string_stream << "LOAD\"" << (is_disk ? "*" : "") << "\"," << device << ",";
 		if(files.front().is_basic()) {
@@ -94,16 +95,18 @@ Analyser::Static::TargetList Analyser::Static::Commodore::GetTargets(const Media
 			default:
 				LOG("Unrecognised loading address for Commodore program: " << PADHEX(4) <<  files.front().starting_address);
 			case 0x1001:
-				target->memory_model = Target::MemoryModel::Unexpanded;
+				memory_model = Target::MemoryModel::Unexpanded;
 			break;
 			case 0x1201:
-				target->memory_model = Target::MemoryModel::ThirtyTwoKB;
+				memory_model = Target::MemoryModel::ThirtyTwoKB;
 			break;
 			case 0x0401:
-				target->memory_model = Target::MemoryModel::EightKB;
+				memory_model = Target::MemoryModel::EightKB;
 			break;
 		}
 
+		target->set_memory_model(memory_model);
+
 		// General approach: increase memory size conservatively such that the largest file found will fit.
 //		for(File &file : files) {
 //			std::size_t file_size = file.data.size();
@@ -145,13 +148,52 @@ Analyser::Static::TargetList Analyser::Static::Commodore::GetTargets(const Media
 	}
 
 	if(!target->media.empty()) {
-		// Inspect filename for a region hint.
+		// Inspect filename for configuration hints.
 		std::string lowercase_name = file_name;
 		std::transform(lowercase_name.begin(), lowercase_name.end(), lowercase_name.begin(), ::tolower);
+
+		// Hint 1: 'ntsc' anywhere in the name implies America.
 		if(lowercase_name.find("ntsc") != std::string::npos) {
 			target->region = Analyser::Static::Commodore::Target::Region::American;
 		}
 
+		// Potential additional hints: check for TheC64 tags.
+		auto final_underscore = lowercase_name.find_last_of('_');
+		if(final_underscore != std::string::npos) {
+			auto iterator = lowercase_name.begin() + ssize_t(final_underscore) + 1;
+
+			while(iterator != lowercase_name.end()) {
+				// Grab the next tag.
+				char next_tag[3] = {0, 0, 0};
+				next_tag[0] = *iterator++;
+				if(iterator == lowercase_name.end()) break;
+				next_tag[1] = *iterator++;
+
+				// Exit early if attempting to read another tag has run over the file extension.
+				if(next_tag[0] == '.' || next_tag[1] == '.') break;
+
+				// Check whether it's anything.
+				target->enabled_ram.bank0 |= !strcmp(next_tag, "b0");
+				target->enabled_ram.bank1 |= !strcmp(next_tag, "b1");
+				target->enabled_ram.bank2 |= !strcmp(next_tag, "b2");
+				target->enabled_ram.bank3 |= !strcmp(next_tag, "b3");
+				target->enabled_ram.bank5 |= !strcmp(next_tag, "b5");
+				if(!strcmp(next_tag, "tn")) {	// i.e. NTSC.
+					target->region = Analyser::Static::Commodore::Target::Region::American;
+				}
+				if(!strcmp(next_tag, "tp")) {	// i.e. PAL.
+					target->region = Analyser::Static::Commodore::Target::Region::European;
+				}
+
+				// Unhandled:
+				//
+				//	M6: 	this is a C64 file.
+				//	MV: 	this is a Vic-20 file.
+				//	J1/J2:	this C64 file should have the primary joystick in slot 1/2.
+				//	RO:		this disk image should be treated as read-only.
+			}
+		}
+
 		// Attach a 1540 if there are any disks here.
 		target->has_c1540 = !target->media.disks.empty();
 

Analyser/Static/Commodore/Target.hpp

@@ -31,7 +31,26 @@ struct Target: public ::Analyser::Static::Target {
 		Swedish
 	};
 
-	MemoryModel memory_model = MemoryModel::Unexpanded;
+	/// Maps from a named memory model to a bank enabled/disabled set.
+	void set_memory_model(MemoryModel memory_model) {
+		// This is correct for unexpanded and 32kb memory models.
+		enabled_ram.bank0 = enabled_ram.bank1 =
+		enabled_ram.bank2 = enabled_ram.bank3 =
+		enabled_ram.bank5 = memory_model == MemoryModel::ThirtyTwoKB;
+
+		// Bank 0 will need to be enabled if this is an 8kb machine.
+		enabled_ram.bank0 |= memory_model == MemoryModel::EightKB;
+	}
+	struct {
+		bool bank0 = false;
+		bool bank1 = false;
+		bool bank2 = false;
+		bool bank3 = false;
+		bool bank5 = false;
+					// Sic. There is no bank 4; this is because the area that logically would be
+					// bank 4 is occupied by the character ROM, colour RAM, hardware registers, etc.
+	} enabled_ram;
+
 	Region region = Region::European;
 	bool has_c1540 = false;
 	std::string loading_command;

Analyser/Static/MSX/StaticAnalyser.cpp

@@ -34,7 +34,7 @@ static std::unique_ptr<Analyser::Static::Target> CartridgeTarget(
 		output_segments.emplace_back(start_address, segment.data);
 	}
 
-	std::unique_ptr<Analyser::Static::MSX::Target> target(new Analyser::Static::MSX::Target);
+	auto target = std::make_unique<Analyser::Static::MSX::Target>();
 	target->machine = Analyser::Machine::MSX;
 	target->confidence = confidence;
 
@@ -269,7 +269,7 @@ Analyser::Static::TargetList Analyser::Static::MSX::GetTargets(const Media &medi
 	std::move(cartridge_targets.begin(), cartridge_targets.end(), std::back_inserter(destination));
 
 	// Consider building a target for disks and/or tapes.
-	std::unique_ptr<Target> target(new Target);
+	auto target = std::make_unique<Target>();
 
 	// Check tapes for loadable files.
 	for(auto &tape : media.tapes) {

Analyser/Static/Macintosh/StaticAnalyser.cpp

@@ -10,10 +10,10 @@
 #include "Target.hpp"
 
 Analyser::Static::TargetList Analyser::Static::Macintosh::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
-	// This analyser can comprehend disks only.
+	// This analyser can comprehend disks and mass-storage devices only.
-	if(media.disks.empty()) return {};
+	if(media.disks.empty() && media.mass_storage_devices.empty()) return {};
 
-	// If there is at least one disk, wave it through.
+	// As there is at least one usable media image, wave it through.
 	Analyser::Static::TargetList targets;
 
 	using Target = Analyser::Static::Macintosh::Target;

Analyser/Static/Macintosh/Target.hpp

@@ -21,7 +21,7 @@ struct Target: public ::Analyser::Static::Target {
 		MacPlus
 	};
 
-	Model model = Model::Mac512ke;
+	Model model = Model::MacPlus;
 };
 
 }

Analyser/Static/Oric/StaticAnalyser.cpp

@@ -20,7 +20,9 @@
 
 using namespace Analyser::Static::Oric;
 
-static int Score(const Analyser::Static::MOS6502::Disassembly &disassembly, const std::set<uint16_t> &rom_functions, const std::set<uint16_t> &variable_locations) {
+namespace {
+
+int score(const Analyser::Static::MOS6502::Disassembly &disassembly, const std::set<uint16_t> &rom_functions, const std::set<uint16_t> &variable_locations) {
 	int score = 0;
 
 	for(const auto address : disassembly.outward_calls)		score += (rom_functions.find(address) != rom_functions.end()) ? 1 : -1;
@@ -30,7 +32,7 @@ static int Score(const Analyser::Static::MOS6502::Disassembly &disassembly, cons
 	return score;
 }
 
-static int Basic10Score(const Analyser::Static::MOS6502::Disassembly &disassembly) {
+int basic10_score(const Analyser::Static::MOS6502::Disassembly &disassembly) {
 	const std::set<uint16_t> rom_functions = {
 		0x0228,	0x022b,
 		0xc3ca,	0xc3f8,	0xc448,	0xc47c,	0xc4b5,	0xc4e3,	0xc4e0,	0xc524,	0xc56f,	0xc5a2,	0xc5f8,	0xc60a,	0xc6a5,	0xc6de,	0xc719,	0xc738,
@@ -51,10 +53,10 @@ static int Basic10Score(const Analyser::Static::MOS6502::Disassembly &disassembl
 		0x0228, 0x0229, 0x022a, 0x022b, 0x022c, 0x022d, 0x0230
 	};
 
-	return Score(disassembly, rom_functions, variable_locations);
+	return score(disassembly, rom_functions, variable_locations);
 }
 
-static int Basic11Score(const Analyser::Static::MOS6502::Disassembly &disassembly) {
+int basic11_score(const Analyser::Static::MOS6502::Disassembly &disassembly) {
 	const std::set<uint16_t> rom_functions = {
 		0x0238,	0x023b,	0x023e,	0x0241,	0x0244,	0x0247,
 		0xc3c6,	0xc3f4,	0xc444,	0xc47c,	0xc4a8,	0xc4d3,	0xc4e0,	0xc524,	0xc55f,	0xc592,	0xc5e8,	0xc5fa,	0xc692,	0xc6b3,	0xc6ee,	0xc70d,
@@ -76,10 +78,10 @@ static int Basic11Score(const Analyser::Static::MOS6502::Disassembly &disassembl
 		0x0244, 0x0245, 0x0246, 0x0247, 0x0248, 0x0249, 0x024a, 0x024b, 0x024c
 	};
 
-	return Score(disassembly, rom_functions, variable_locations);
+	return score(disassembly, rom_functions, variable_locations);
 }
 
-static bool IsMicrodisc(Storage::Encodings::MFM::Parser &parser) {
+bool is_microdisc(Storage::Encodings::MFM::Parser &parser) {
 	/*
 		The Microdisc boot sector is sector 2 of track 0 and contains a 23-byte signature.
 	*/
@@ -100,8 +102,51 @@ static bool IsMicrodisc(Storage::Encodings::MFM::Parser &parser) {
 	return !std::memcmp(signature, first_sample.data(), sizeof(signature));
 }
 
+bool is_400_loader(Storage::Encodings::MFM::Parser &parser, uint16_t range_start, uint16_t range_end) {
+	/*
+		Both the Jasmin and BD-DOS boot sectors are sector 1 of track 0 and are loaded at $400;
+		use disassembly to test for likely matches.
+	*/
+
+	Storage::Encodings::MFM::Sector *sector = parser.get_sector(0, 0, 1);
+	if(!sector) return false;
+	if(sector->samples.empty()) return false;
+
+	// Take a copy of the first sampling, and keep only the final 256 bytes (assuming at least that many were found).
+	std::vector<uint8_t> first_sample = sector->samples[0];
+	if(first_sample.size() < 256) return false;
+	if(first_sample.size() > 256) {
+		first_sample.erase(first_sample.end() - 256, first_sample.end());
+	}
+
+	// Grab a disassembly.
+	const auto disassembly =
+		Analyser::Static::MOS6502::Disassemble(first_sample, Analyser::Static::Disassembler::OffsetMapper(0x400), {0x400});
+
+	// Check for references to the Jasmin registers.
+	int register_hits = 0;
+	for(auto list : {disassembly.external_stores, disassembly.external_loads, disassembly.external_modifies}) {
+		for(auto address : list) {
+			register_hits += (address >= range_start && address <= range_end);
+		}
+	}
+
+	// Arbitrary, sure, but as long as at least two accesses to the requested register range are found, accept this.
+	return register_hits >= 2;
+}
+
+bool is_jasmin(Storage::Encodings::MFM::Parser &parser) {
+	return is_400_loader(parser, 0x3f4, 0x3ff);
+}
+
+bool is_bd500(Storage::Encodings::MFM::Parser &parser) {
+	return is_400_loader(parser, 0x310, 0x323);
+}
+
+}
+
 Analyser::Static::TargetList Analyser::Static::Oric::GetTargets(const Media &media, const std::string &file_name, TargetPlatform::IntType potential_platforms) {
-	std::unique_ptr<Target> target(new Target);
+	auto target = std::make_unique<Target>();
 	target->machine = Machine::Oric;
 	target->confidence = 0.5;
 
@@ -115,12 +160,10 @@ Analyser::Static::TargetList Analyser::Static::Oric::GetTargets(const Media &med
 			for(const auto &file : tape_files) {
 				if(file.data_type == File::MachineCode) {
 					std::vector<uint16_t> entry_points = {file.starting_address};
-					Analyser::Static::MOS6502::Disassembly disassembly =
+					const Analyser::Static::MOS6502::Disassembly disassembly =
 						Analyser::Static::MOS6502::Disassemble(file.data, Analyser::Static::Disassembler::OffsetMapper(file.starting_address), entry_points);
 
-					int basic10_score = Basic10Score(disassembly);
+					if(basic10_score(disassembly) > basic11_score(disassembly)) ++basic10_votes; else ++basic11_votes;
-					int basic11_score = Basic11Score(disassembly);
-					if(basic10_score > basic11_score) basic10_votes++; else basic11_votes++;
 				}
 			}
 
@@ -130,12 +173,22 @@ Analyser::Static::TargetList Analyser::Static::Oric::GetTargets(const Media &med
 	}
 
 	if(!media.disks.empty()) {
-		// Only the Microdisc is emulated right now, so accept only disks that it can boot from.
+		// 8-DOS is recognised by a dedicated Disk II analyser, so check only for Microdisc,
+		// Jasmin and BD-DOS formats here.
 		for(auto &disk: media.disks) {
 			Storage::Encodings::MFM::Parser parser(true, disk);
-			if(IsMicrodisc(parser)) {
+
+			if(is_microdisc(parser)) {
 				target->disk_interface = Target::DiskInterface::Microdisc;
 				target->media.disks.push_back(disk);
+			} else if(is_jasmin(parser)) {
+				target->disk_interface = Target::DiskInterface::Jasmin;
+				target->should_start_jasmin = true;
+				target->media.disks.push_back(disk);
+			} else if(is_bd500(parser)) {
+				target->disk_interface = Target::DiskInterface::BD500;
+				target->media.disks.push_back(disk);
+				target->rom = Target::ROM::BASIC10;
 			}
 		}
 	}

Analyser/Static/Oric/Target.hpp

@@ -26,12 +26,15 @@ struct Target: public ::Analyser::Static::Target {
 	enum class DiskInterface {
 		Microdisc,
 		Pravetz,
+		Jasmin,
+		BD500,
 		None
 	};
 
 	ROM rom = ROM::BASIC11;
 	DiskInterface disk_interface = DiskInterface::None;
 	std::string loading_command;
+	bool should_start_jasmin = false;
 };
 
 }

Analyser/Static/Sega/StaticAnalyser.cpp

@@ -18,7 +18,7 @@ Analyser::Static::TargetList Analyser::Static::Sega::GetTargets(const Media &med
 		return {};
 
 	TargetList targets;
-	std::unique_ptr<Target> target(new Target);
+	auto target = std::make_unique<Target>();
 
 	target->machine = Machine::MasterSystem;
 

Analyser/Static/StaticAnalyser.cpp

@@ -17,7 +17,8 @@
 #include "Acorn/StaticAnalyser.hpp"
 #include "AmstradCPC/StaticAnalyser.hpp"
 #include "AppleII/StaticAnalyser.hpp"
-#include "Atari/StaticAnalyser.hpp"
+#include "Atari2600/StaticAnalyser.hpp"
+#include "AtariST/StaticAnalyser.hpp"
 #include "Coleco/StaticAnalyser.hpp"
 #include "Commodore/StaticAnalyser.hpp"
 #include "DiskII/StaticAnalyser.hpp"
@@ -40,12 +41,18 @@
 #include "../../Storage/Disk/DiskImage/Formats/G64.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/DMK.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"
+#include "../../Storage/Disk/DiskImage/Formats/ST.hpp"
+#include "../../Storage/Disk/DiskImage/Formats/STX.hpp"
 #include "../../Storage/Disk/DiskImage/Formats/WOZ.hpp"
 
+// Mass Storage Devices (i.e. usually, hard disks)
+#include "../../Storage/MassStorage/Formats/HFV.hpp"
+
 // Tapes
 #include "../../Storage/Tape/Formats/CAS.hpp"
 #include "../../Storage/Tape/Formats/CommodoreTAP.hpp"
@@ -102,7 +109,8 @@ static Media GetMediaAndPlatforms(const std::string &file_name, TargetPlatform::
 	Format("dsd", result.disks, Disk::DiskImageHolder<Storage::Disk::SSD>, TargetPlatform::Acorn)				// DSD
 	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::CPCDSK>, TargetPlatform::AmstradCPC)		// DSK (Amstrad CPC)
 	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::AppleDSK>, TargetPlatform::DiskII)			// DSK (Apple II)
-	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::MacintoshIMG>, TargetPlatform::Macintosh)	// DSK (Macintosh)
+	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)
 	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::MSXDSK>, 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
@@ -113,6 +121,7 @@ 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("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
 	Format("p", result.tapes, Tape::ZX80O81P, TargetPlatform::ZX8081)											// P
@@ -138,6 +147,8 @@ static Media GetMediaAndPlatforms(const std::string &file_name, TargetPlatform::
 	Format("sg", result.cartridges, Cartridge::BinaryDump, TargetPlatform::Sega)								// SG
 	Format("sms", result.cartridges, Cartridge::BinaryDump, TargetPlatform::Sega)								// SMS
 	Format("ssd", result.disks, Disk::DiskImageHolder<Storage::Disk::SSD>, TargetPlatform::Acorn)				// SSD
+	Format("st", result.disks, Disk::DiskImageHolder<Storage::Disk::ST>, TargetPlatform::AtariST)				// ST
+	Format("stx", result.disks, Disk::DiskImageHolder<Storage::Disk::STX>, TargetPlatform::AtariST)				// STX
 	Format("tap", result.tapes, Tape::CommodoreTAP, TargetPlatform::Commodore)									// TAP (Commodore)
 	Format("tap", result.tapes, Tape::OricTAP, TargetPlatform::Oric)											// TAP (Oric)
 	Format("tsx", result.tapes, Tape::TZX, TargetPlatform::MSX)													// TSX
@@ -160,7 +171,7 @@ Media Analyser::Static::GetMedia(const std::string &file_name) {
 TargetList Analyser::Static::GetTargets(const std::string &file_name) {
 	TargetList targets;
 
-	// Collect all disks, tapes and ROMs as can be extrapolated from this file, forming the
+	// Collect all disks, tapes ROMs, etc as can be extrapolated from this file, forming the
 	// union of all platforms this file might be a target for.
 	TargetPlatform::IntType potential_platforms = 0;
 	Media media = GetMediaAndPlatforms(file_name, potential_platforms);
@@ -174,7 +185,8 @@ TargetList Analyser::Static::GetTargets(const std::string &file_name) {
 	if(potential_platforms & TargetPlatform::Acorn)			Append(Acorn);
 	if(potential_platforms & TargetPlatform::AmstradCPC)	Append(AmstradCPC);
 	if(potential_platforms & TargetPlatform::AppleII)		Append(AppleII);
-	if(potential_platforms & TargetPlatform::Atari2600)		Append(Atari);
+	if(potential_platforms & TargetPlatform::Atari2600)		Append(Atari2600);
+	if(potential_platforms & TargetPlatform::AtariST)		Append(AtariST);
 	if(potential_platforms & TargetPlatform::ColecoVision)	Append(Coleco);
 	if(potential_platforms & TargetPlatform::Commodore)		Append(Commodore);
 	if(potential_platforms & TargetPlatform::DiskII)		Append(DiskII);

Analyser/Static/StaticAnalyser.hpp

@@ -11,9 +11,10 @@
 
 #include "../Machines.hpp"
 
-#include "../../Storage/Tape/Tape.hpp"
-#include "../../Storage/Disk/Disk.hpp"
 #include "../../Storage/Cartridge/Cartridge.hpp"
+#include "../../Storage/Disk/Disk.hpp"
+#include "../../Storage/MassStorage/MassStorageDevice.hpp"
+#include "../../Storage/Tape/Tape.hpp"
 
 #include <memory>
 #include <string>
@@ -29,9 +30,10 @@ struct Media {
 	std::vector<std::shared_ptr<Storage::Disk::Disk>> disks;
 	std::vector<std::shared_ptr<Storage::Tape::Tape>> tapes;
 	std::vector<std::shared_ptr<Storage::Cartridge::Cartridge>> cartridges;
+	std::vector<std::shared_ptr<Storage::MassStorage::MassStorageDevice>> mass_storage_devices;
 
 	bool empty() const {
-		return disks.empty() && tapes.empty() && cartridges.empty();
+		return disks.empty() && tapes.empty() && cartridges.empty() && mass_storage_devices.empty();
 	}
 };
 

ClockReceiver/ClockReceiver.hpp

@@ -10,6 +10,7 @@
 #define ClockReceiver_hpp
 
 #include "ForceInline.hpp"
+#include <cstdint>
 
 /*
 	Informal pattern for all classes that run from a clock cycle:
@@ -54,7 +55,9 @@
 */
 template <class T> class WrappedInt {
 	public:
-		forceinline constexpr WrappedInt(int l) noexcept : length_(l) {}
+		using IntType = int64_t;
+
+		forceinline constexpr WrappedInt(IntType l) noexcept : length_(l) {}
 		forceinline constexpr WrappedInt() noexcept : length_(0) {}
 
 		forceinline T &operator =(const T &rhs) {
@@ -133,16 +136,20 @@ template <class T> class WrappedInt {
 		forceinline constexpr bool operator !() const					{	return !length_;					}
 		// bool operator () is not supported because it offers an implicit cast to int, which is prone silently to permit misuse
 
-		forceinline constexpr int as_int() const { return length_; }
+		/// @returns The underlying int, cast to an integral type of your choosing.
+		template<typename Type = IntType> forceinline constexpr Type as() const { return Type(length_); }
+
+		/// @returns The underlying int, in its native form.
+		forceinline constexpr IntType as_integral() const { return length_; }
 
 		/*!
 			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.
 		*/
-		forceinline T divide(const T &divisor) {
+		template <typename Result = T> forceinline Result divide(const T &divisor) {
-			T result(length_ / divisor.length_);
+			Result r;
-			length_ %= divisor.length_;
+			static_cast<T *>(this)->fill(r, divisor);
-			return result;
+			return r;
 		}
 
 		/*!
@@ -161,13 +168,13 @@ template <class T> class WrappedInt {
 		// classes that use this template.
 
 	protected:
-		int length_;
+		IntType length_;
 };
 
 /// Describes an integer number of whole cycles: pairs of clock signal transitions.
 class Cycles: public WrappedInt<Cycles> {
 	public:
-		forceinline constexpr Cycles(int l) noexcept : WrappedInt<Cycles>(l) {}
+		forceinline constexpr Cycles(IntType l) noexcept : WrappedInt<Cycles>(l) {}
 		forceinline constexpr Cycles() noexcept : WrappedInt<Cycles>() {}
 		forceinline constexpr Cycles(const Cycles &cycles) noexcept : WrappedInt<Cycles>(cycles.length_) {}
 
@@ -177,15 +184,20 @@ class Cycles: public WrappedInt<Cycles> {
 			result.length_ = length_;
 			length_ = 0;
 		}
+
+		void fill(Cycles &result, const Cycles &divisor) {
+			result.length_ = length_ / divisor.length_;
+			length_ %= divisor.length_;
+		}
 };
 
 /// Describes an integer number of half cycles: single clock signal transitions.
 class HalfCycles: public WrappedInt<HalfCycles> {
 	public:
-		forceinline constexpr HalfCycles(int l) noexcept : WrappedInt<HalfCycles>(l) {}
+		forceinline constexpr HalfCycles(IntType l) noexcept : WrappedInt<HalfCycles>(l) {}
 		forceinline constexpr HalfCycles() noexcept : WrappedInt<HalfCycles>() {}
 
-		forceinline constexpr HalfCycles(const Cycles &cycles) noexcept : WrappedInt<HalfCycles>(cycles.as_int() * 2) {}
+		forceinline constexpr HalfCycles(const Cycles &cycles) noexcept : WrappedInt<HalfCycles>(cycles.as_integral() * 2) {}
 		forceinline constexpr HalfCycles(const HalfCycles &half_cycles) noexcept : WrappedInt<HalfCycles>(half_cycles.length_) {}
 
 		/// @returns The number of whole cycles completely covered by this span of half cycles.
@@ -215,6 +227,16 @@ class HalfCycles: public WrappedInt<HalfCycles> {
 			result.length_ = length_;
 			length_ = 0;
 		}
+
+		void fill(Cycles &result, const HalfCycles &divisor) {
+			result = Cycles(length_ / (divisor.length_ << 1));
+			length_ %= (divisor.length_ << 1);
+		}
+
+		void fill(HalfCycles &result, const HalfCycles &divisor) {
+			result.length_ = length_ / divisor.length_;
+			length_ %= divisor.length_;
+		}
 };
 
 // Create a specialisation of WrappedInt::flush for converting HalfCycles to Cycles

ClockReceiver/DeferredQueue.hpp

@@ -13,62 +13,68 @@
 #include <vector>
 
 /*!
-	A DeferredQueue maintains a list of ordered actions and the times at which
+	Provides the logic to insert into and traverse a list of future scheduled items.
-	they should happen, and divides a total execution period up into the portions
-	that occur between those actions, triggering each action when it is reached.
 */
 template <typename TimeUnit> class DeferredQueue {
 	public:
-		/// Constructs a DeferredQueue that will call target(period) in between deferred actions.
-		DeferredQueue(std::function<void(TimeUnit)> &&target) : target_(std::move(target)) {}
-
 		/*!
 			Schedules @c action to occur in @c delay units of time.
-
-			Actions must be scheduled in the order they will occur. It is undefined behaviour
-			to schedule them out of order.
 		*/
 		void defer(TimeUnit delay, const std::function<void(void)> &action) {
-			pending_actions_.emplace_back(delay, action);
+			// Apply immediately if there's no delay (or a negative delay).
-		}
+			if(delay <= TimeUnit(0)) {
-
+				action();
-		/*!
-			Runs for @c length units of time.
-
-			The constructor-supplied target will be called with one or more periods that add up to @c length;
-			any scheduled actions will be called between periods.
-		*/
-		void run_for(TimeUnit length) {
-			// If there are no pending actions, just run for the entire length.
-			// This should be the normal branch.
-			if(pending_actions_.empty()) {
-				target_(length);
 				return;
 			}
 
-			// Divide the time to run according to the pending actions.
+			if(!pending_actions_.empty()) {
-			while(length > TimeUnit(0)) {
+				// Otherwise enqueue, having subtracted the delay for any preceding events,
-				TimeUnit next_period = pending_actions_.empty() ? length : std::min(length, pending_actions_[0].delay);
+				// and subtracting from the subsequent, if any.
-				target_(next_period);
+				auto insertion_point = pending_actions_.begin();
-				length -= next_period;
+				while(insertion_point != pending_actions_.end() && insertion_point->delay < delay) {
+					delay -= insertion_point->delay;
+					++insertion_point;
+				}
+				if(insertion_point != pending_actions_.end()) {
+					insertion_point->delay -= delay;
+				}
 
-				off_t performances = 0;
+				pending_actions_.emplace(insertion_point, delay, action);
-				for(auto &action: pending_actions_) {
+			} else {
-					action.delay -= next_period;
+				pending_actions_.emplace_back(delay, action);
-					if(!action.delay) {
-						action.action();
-						++performances;
 			}
 		}
-				if(performances) {
+
-					pending_actions_.erase(pending_actions_.begin(), pending_actions_.begin() + performances);
+		/*!
+			@returns The amount of time until the next enqueued action will occur,
+				or TimeUnit(-1) if the queue is empty.
+		*/
+		TimeUnit time_until_next_action() {
+			if(pending_actions_.empty()) return TimeUnit(-1);
+			return pending_actions_.front().delay;
 		}
+
+		/*!
+			Advances the queue the specified amount of time, performing any actions it reaches.
+		*/
+		void advance(TimeUnit time) {
+			auto erase_iterator = pending_actions_.begin();
+			while(erase_iterator != pending_actions_.end()) {
+				erase_iterator->delay -= time;
+				if(erase_iterator->delay <= TimeUnit(0)) {
+					time = -erase_iterator->delay;
+					erase_iterator->action();
+					++erase_iterator;
+				} else {
+					break;
+				}
+			}
+			if(erase_iterator != pending_actions_.begin()) {
+				pending_actions_.erase(pending_actions_.begin(), erase_iterator);
 			}
 		}
 
 	private:
-		std::function<void(TimeUnit)> target_;
-
 		// The list of deferred actions.
 		struct DeferredAction {
 			TimeUnit delay;
@@ -79,4 +85,40 @@ template <typename TimeUnit> class DeferredQueue {
 		std::vector<DeferredAction> pending_actions_;
 };
 
+/*!
+	A DeferredQueue maintains a list of ordered actions and the times at which
+	they should happen, and divides a total execution period up into the portions
+	that occur between those actions, triggering each action when it is reached.
+
+	This list is efficient only for short queues.
+*/
+template <typename TimeUnit> class DeferredQueuePerformer: public DeferredQueue<TimeUnit> {
+	public:
+		/// Constructs a DeferredQueue that will call target(period) in between deferred actions.
+		DeferredQueuePerformer(std::function<void(TimeUnit)> &&target) : target_(std::move(target)) {}
+
+		/*!
+			Runs for @c length units of time.
+
+			The constructor-supplied target will be called with one or more periods that add up to @c length;
+			any scheduled actions will be called between periods.
+		*/
+		void run_for(TimeUnit length) {
+			auto time_to_next = DeferredQueue<TimeUnit>::time_until_next_action();
+			while(time_to_next != TimeUnit(-1) && time_to_next <= length) {
+				target_(time_to_next);
+				length -= time_to_next;
+				DeferredQueue<TimeUnit>::advance(time_to_next);
+			}
+
+			DeferredQueue<TimeUnit>::advance(length);
+			target_(length);
+
+			// TODO: optimise this to avoid the multiple std::vector deletes. Find a neat way to expose that solution, maybe?
+		}
+
+	private:
+		std::function<void(TimeUnit)> target_;
+};
+
 #endif /* DeferredQueue_h */

ClockReceiver/ForceInline.hpp

@@ -9,9 +9,9 @@
 #ifndef ForceInline_hpp
 #define ForceInline_hpp
 
-#ifdef DEBUG
+#ifndef NDEBUG
 
-#define forceinline
+#define forceinline inline
 
 #else
 

ClockReceiver/JustInTime.hpp

@@ -10,6 +10,7 @@
 #define JustInTime_h
 
 #include "../Concurrency/AsyncTaskQueue.hpp"
+#include "ForceInline.hpp"
 
 /*!
 	A JustInTimeActor holds (i) an embedded object with a run_for method; and (ii) an amount
@@ -21,32 +22,52 @@
 	Machines that accumulate HalfCycle time but supply to a Cycle-counted device may supply a
 	separate @c TargetTimeScale at template declaration.
 */
-template <class T, class LocalTimeScale, class TargetTimeScale = LocalTimeScale> class JustInTimeActor {
+template <class T, int multiplier = 1, int divider = 1, class LocalTimeScale = HalfCycles, class TargetTimeScale = LocalTimeScale> class JustInTimeActor {
 	public:
 		/// Constructs a new JustInTimeActor using the same construction arguments as the included object.
 		template<typename... Args> JustInTimeActor(Args&&... args) : object_(std::forward<Args>(args)...) {}
 
 		/// Adds time to the actor.
-		inline void operator += (const LocalTimeScale &rhs) {
+		forceinline void operator += (const LocalTimeScale &rhs) {
+			if constexpr (multiplier != 1) {
+				time_since_update_ += rhs * multiplier;
+			} else {
 				time_since_update_ += rhs;
+			}
 			is_flushed_ = false;
 		}
 
 		/// Flushes all accumulated time and returns a pointer to the included object.
-		inline T *operator->() {
+		forceinline T *operator->() {
 			flush();
 			return &object_;
 		}
 
+		/// Acts exactly as per the standard ->, but preserves constness.
+		forceinline const T *operator->() const {
+			auto non_const_this = const_cast<JustInTimeActor<T, multiplier, divider, LocalTimeScale, TargetTimeScale> *>(this);
+			non_const_this->flush();
+			return &object_;
+		}
+
 		/// Returns a pointer to the included object without flushing time.
-		inline T *last_valid() {
+		forceinline T *last_valid() {
 			return &object_;
 		}
 
 		/// Flushes all accumulated time.
-		inline void flush() {
+		forceinline void flush() {
-			if(!is_flushed_) object_.run_for(time_since_update_.template flush<TargetTimeScale>());
+			if(!is_flushed_) {
 				is_flushed_ = true;
+				if constexpr (divider == 1) {
+					const auto duration = time_since_update_.template flush<TargetTimeScale>();
+					object_.run_for(duration);
+				} else {
+					const auto duration = time_since_update_.template divide<TargetTimeScale>(LocalTimeScale(divider));
+					if(duration > TargetTimeScale(0))
+						object_.run_for(duration);
+				}
+			}
 		}
 
 	private:
@@ -55,12 +76,54 @@ template <class T, class LocalTimeScale, class TargetTimeScale = LocalTimeScale>
 		bool is_flushed_ = true;
 };
 
+/*!
+	A RealTimeActor presents the same interface as a JustInTimeActor but doesn't defer work.
+	Time added will be performed immediately.
+
+	Its primary purpose is to allow consumers to remain flexible in their scheduling.
+*/
+template <class T, int multiplier = 1, int divider = 1, class LocalTimeScale = HalfCycles, class TargetTimeScale = LocalTimeScale> class RealTimeActor {
+	public:
+		template<typename... Args> RealTimeActor(Args&&... args) : object_(std::forward<Args>(args)...) {}
+
+		forceinline void operator += (const LocalTimeScale &rhs) {
+			if constexpr (multiplier == 1 && divider == 1) {
+				object_.run_for(TargetTimeScale(rhs));
+				return;
+			}
+
+			if constexpr (multiplier == 1) {
+				accumulated_time_ += rhs;
+			} else {
+				accumulated_time_ += rhs * multiplier;
+			}
+
+			if constexpr (divider == 1) {
+				const auto duration = accumulated_time_.template flush<TargetTimeScale>();
+				object_.run_for(duration);
+			} else {
+				const auto duration = accumulated_time_.template divide<TargetTimeScale>(LocalTimeScale(divider));
+				if(duration > TargetTimeScale(0))
+					object_.run_for(duration);
+			}
+		}
+
+		forceinline T *operator->()				{	return &object_;	}
+		forceinline const T *operator->() const	{	return &object_;	}
+		forceinline T *last_valid() 			{	return &object_;	}
+		forceinline void flush()				{}
+
+	private:
+		T object_;
+		LocalTimeScale accumulated_time_;
+};
+
 /*!
 	A AsyncJustInTimeActor acts like a JustInTimeActor but additionally contains an AsyncTaskQueue.
 	Any time the amount of accumulated time crosses a threshold provided at construction time,
 	the object will be updated on the AsyncTaskQueue.
 */
-template <class T, class LocalTimeScale, class TargetTimeScale = LocalTimeScale> class AsyncJustInTimeActor {
+template <class T, class LocalTimeScale = HalfCycles, class TargetTimeScale = LocalTimeScale> class AsyncJustInTimeActor {
 	public:
 		/// Constructs a new AsyncJustInTimeActor using the same construction arguments as the included object.
 		template<typename... Args> AsyncJustInTimeActor(TargetTimeScale threshold, Args&&... args) :

ClockReceiver/ScanSynchroniser.hpp

@@ -0,0 +1,88 @@
+//
+//  ScanSynchroniser.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 09/02/2020.
+//  Copyright © 2020 Thomas Harte. All rights reserved.
+//
+
+#ifndef ScanSynchroniser_h
+#define ScanSynchroniser_h
+
+#include "../Outputs/ScanTarget.hpp"
+
+#include <cmath>
+
+namespace Time {
+
+/*!
+	Where an emulated machine is sufficiently close to a host machine's frame rate that a small nudge in
+	its speed multiplier will bring it into frame synchronisation, the ScanSynchroniser provides a sequence of
+	speed multipliers designed both to adjust the machine to the proper speed and, in a reasonable amount
+	of time, to bring it into phase.
+*/
+class ScanSynchroniser {
+	public:
+		/*!
+			@returns @c true if the emulated machine can be synchronised with the host frame output based on its
+				current @c [scan]status and the host machine's @c frame_duration; @c false otherwise.
+		*/
+		bool can_synchronise(const Outputs::Display::ScanStatus &scan_status, double frame_duration) {
+			ratio_ = 1.0;
+			if(scan_status.field_duration_gradient < 0.00001) {
+				// Check out the machine's current frame time.
+				// If it's within 3% of a non-zero integer multiple of the
+				// display rate, mark this time window to be split over the sync.
+				ratio_ = (frame_duration * base_multiplier_) / scan_status.field_duration;
+				const double integer_ratio = round(ratio_);
+				if(integer_ratio > 0.0) {
+					ratio_ /= integer_ratio;
+					return ratio_ <= maximum_rate_adjustment && ratio_ >= 1.0 / maximum_rate_adjustment;
+				}
+			}
+			return false;
+		}
+
+		/*!
+			@returns The appropriate speed multiplier for the next frame based on the inputs previously supplied to @c can_synchronise.
+				Results are undefined if @c can_synchroise returned @c false.
+		*/
+		double next_speed_multiplier(const Outputs::Display::ScanStatus &scan_status) {
+			// The host versus emulated ratio is calculated based on the current perceived frame duration of the machine.
+			// Either that number is exactly correct or it's already the result of some sort of low-pass filter. So there's
+			// no benefit to second guessing it here — just take it to be correct.
+			//
+			// ... with one slight caveat, which is that it is desireable to adjust phase here, to align vertical sync points.
+			// So the set speed multiplier may be adjusted slightly to aim for that.
+			double speed_multiplier = 1.0 / (ratio_ / base_multiplier_);
+			if(scan_status.current_position > 0.0) {
+				if(scan_status.current_position < 0.5) speed_multiplier /= phase_adjustment_ratio;
+				else speed_multiplier *= phase_adjustment_ratio;
+			}
+			speed_multiplier_ = (speed_multiplier_ * 0.95) + (speed_multiplier * 0.05);
+			return speed_multiplier_ * base_multiplier_;
+		}
+
+		void set_base_speed_multiplier(double multiplier) {
+			base_multiplier_ = multiplier;
+		}
+
+		double get_base_speed_multiplier() {
+			return base_multiplier_;
+		}
+
+	private:
+		static constexpr double maximum_rate_adjustment = 1.03;
+		static constexpr double phase_adjustment_ratio = 1.005;
+
+		// Managed local state.
+		double speed_multiplier_ = 1.0;
+		double base_multiplier_ = 1.0;
+
+		// Temporary storage to bridge the can_synchronise -> next_speed_multiplier gap.
+		double ratio_ = 1.0;
+};
+
+}
+
+#endif /* ScanSynchroniser_h */

ClockReceiver/TimeTypes.hpp

@@ -9,9 +9,16 @@
 #ifndef TimeTypes_h
 #define TimeTypes_h
 
+#include <chrono>
+
 namespace Time {
 
 typedef double Seconds;
+typedef int64_t Nanos;
+
+inline Nanos nanos_now() {
+	return std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::high_resolution_clock::now().time_since_epoch()).count();
+}
 
 }
 

Components/1770/1770.cpp

@@ -9,6 +9,8 @@
 #include "1770.hpp"
 
 #include "../../Storage/Disk/Encodings/MFM/Constants.hpp"
+
+#define LOG_PREFIX "[WD FDC] "
 #include "../../Outputs/Log.hpp"
 
 using namespace WD;
@@ -16,19 +18,19 @@ using namespace WD;
 WD1770::WD1770(Personality p) :
 		Storage::Disk::MFMController(8000000),
 		personality_(p),
-		interesting_event_mask_(static_cast<int>(Event1770::Command)) {
+		interesting_event_mask_(int(Event1770::Command)) {
 	set_is_double_density(false);
-	posit_event(static_cast<int>(Event1770::Command));
+	posit_event(int(Event1770::Command));
 }
 
-void WD1770::set_register(int address, uint8_t value) {
+void WD1770::write(int address, uint8_t value) {
 	switch(address&3) {
 		case 0: {
 			if((value&0xf0) == 0xd0) {
 				if(value == 0xd0) {
 					// Force interrupt **immediately**.
 					LOG("Force interrupt immediately");
-					posit_event(static_cast<int>(Event1770::ForceInterrupt));
+					posit_event(int(Event1770::ForceInterrupt));
 				} else {
 					ERROR("!!!TODO: force interrupt!!!");
 					update_status([] (Status &status) {
@@ -37,7 +39,7 @@ void WD1770::set_register(int address, uint8_t value) {
 				}
 			} else {
 				command_ = value;
-				posit_event(static_cast<int>(Event1770::Command));
+				posit_event(int(Event1770::Command));
 			}
 		}
 		break;
@@ -52,27 +54,35 @@ void WD1770::set_register(int address, uint8_t value) {
 	}
 }
 
-uint8_t WD1770::get_register(int address) {
+uint8_t WD1770::read(int address) {
 	switch(address&3) {
 		default: {
 			update_status([] (Status &status) {
 				status.interrupt_request = false;
 			});
 			uint8_t status =
-					(status_.write_protect ? Flag::WriteProtect : 0) |
 				(status_.crc_error ? Flag::CRCError : 0) |
 				(status_.busy ? Flag::Busy : 0);
+
+			// Per Jean Louis-Guérin's documentation:
+			//
+			//	* 	the write-protect bit is locked into place by a type 2 or type 3 command, but is
+			//		read live after a type 1.
+			//	*	the track 0 bit is captured during a type 1 instruction and lost upon any other type,
+			//		it is not live sampled.
 			switch(status_.type) {
 				case Status::One:
 					status |=
-						(get_drive().get_is_track_zero() ? Flag::TrackZero : 0) |
+						(status_.track_zero ? Flag::TrackZero : 0) |
-						(status_.seek_error ? Flag::SeekError : 0);
+						(status_.seek_error ? Flag::SeekError : 0) |
-						// TODO: index hole
+						(get_drive().get_is_read_only() ? Flag::WriteProtect : 0) |
+						(get_drive().get_index_pulse() ? Flag::Index : 0);
 				break;
 
 				case Status::Two:
 				case Status::Three:
 					status |=
+						(status_.write_protect ? Flag::WriteProtect : 0) |
 						(status_.record_type ? Flag::RecordType : 0) |
 						(status_.lost_data ? Flag::LostData : 0) |
 						(status_.data_request ? Flag::DataRequest : 0) |
@@ -89,10 +99,15 @@ uint8_t WD1770::get_register(int address) {
 				if(status_.type == Status::One)
 					status |= (status_.spin_up ? Flag::SpinUp : 0);
 			}
+//			LOG("Returned status " << PADHEX(2) << int(status) << " of type " << 1+int(status_.type));
 			return status;
 		}
-		case 1:		return track_;
+		case 1:
-		case 2:		return sector_;
+			LOG("Returned track " << int(track_));
+			return track_;
+		case 2:
+			LOG("Returned sector " << int(sector_));
+			return sector_;
 		case 3:
 			update_status([] (Status &status) {
 				status.data_request = false;
@@ -105,28 +120,30 @@ void WD1770::run_for(const Cycles cycles) {
 	Storage::Disk::Controller::run_for(cycles);
 
 	if(delay_time_) {
-		unsigned int number_of_cycles = static_cast<unsigned int>(cycles.as_int());
+		const auto number_of_cycles = cycles.as_integral();
 		if(delay_time_ <= number_of_cycles) {
 			delay_time_ = 0;
-			posit_event(static_cast<int>(Event1770::Timer));
+			posit_event(int(Event1770::Timer));
 		} else {
 			delay_time_ -= number_of_cycles;
 		}
 	}
 }
 
-#define WAIT_FOR_EVENT(mask)	resume_point_ = __LINE__; interesting_event_mask_ = static_cast<int>(mask); return; case __LINE__:
+#define WAIT_FOR_EVENT(mask)	resume_point_ = __LINE__; interesting_event_mask_ = int(mask); return; case __LINE__:
 #define WAIT_FOR_TIME(ms)		resume_point_ = __LINE__; delay_time_ = ms * 8000; WAIT_FOR_EVENT(Event1770::Timer);
-#define WAIT_FOR_BYTES(count)	resume_point_ = __LINE__; distance_into_section_ = 0; WAIT_FOR_EVENT(Event::Token); if(get_latest_token().type == Token::Byte) distance_into_section_++; if(distance_into_section_ < count) { interesting_event_mask_ = static_cast<int>(Event::Token); return; }
+#define WAIT_FOR_BYTES(count)	resume_point_ = __LINE__; distance_into_section_ = 0; WAIT_FOR_EVENT(Event::Token); if(get_latest_token().type == Token::Byte) distance_into_section_++; if(distance_into_section_ < count) { interesting_event_mask_ = int(Event::Token); return; }
 #define BEGIN_SECTION()	switch(resume_point_) { default:
 #define END_SECTION()	(void)0; }
 
 #define READ_ID()	\
-		if(new_event_type == static_cast<int>(Event::Token)) {	\
+		if(new_event_type == int(Event::Token)) {	\
-			if(!distance_into_section_ && get_latest_token().type == Token::ID) {set_data_mode(DataMode::Reading); distance_into_section_++; }	\
+			if(!distance_into_section_ && get_latest_token().type == Token::ID) {\
-			else if(distance_into_section_ && distance_into_section_ < 7 && get_latest_token().type == Token::Byte) {	\
+				set_data_mode(DataMode::Reading);	\
+				++distance_into_section_;	\
+			} else if(distance_into_section_ && distance_into_section_ < 7 && get_latest_token().type == Token::Byte) {	\
 				header_[distance_into_section_ - 1] = get_latest_token().byte_value;	\
-				distance_into_section_++;	\
+				++distance_into_section_;	\
 			}	\
 		}
 
@@ -159,10 +176,10 @@ void WD1770::run_for(const Cycles cycles) {
 // +--------+----------+-------------------------+
 
 void WD1770::posit_event(int new_event_type) {
-	if(new_event_type == static_cast<int>(Event::IndexHole)) {
+	if(new_event_type == int(Event::IndexHole)) {
 		index_hole_count_++;
 		if(index_hole_count_target_ == index_hole_count_) {
-			posit_event(static_cast<int>(Event1770::IndexHoleTarget));
+			posit_event(int(Event1770::IndexHoleTarget));
 			index_hole_count_target_ = -1;
 		}
 
@@ -177,15 +194,16 @@ void WD1770::posit_event(int new_event_type) {
 		}
 	}
 
-	if(new_event_type == static_cast<int>(Event1770::ForceInterrupt)) {
+	if(new_event_type == int(Event1770::ForceInterrupt)) {
 		interesting_event_mask_ = 0;
 		resume_point_ = 0;
 		update_status([] (Status &status) {
 			status.type = Status::One;
 			status.data_request = false;
+			status.spin_up = false;
 		});
 	} else {
-		if(!(interesting_event_mask_ & static_cast<int>(new_event_type))) return;
+		if(!(interesting_event_mask_ & int(new_event_type))) return;
 		interesting_event_mask_ &= ~new_event_type;
 	}
 
@@ -208,6 +226,7 @@ void WD1770::posit_event(int new_event_type) {
 		update_status([] (Status &status) {
 			status.busy = true;
 			status.interrupt_request = false;
+			status.track_zero = false;	// Always reset by a non-type 1; so reset regardless and set properly later.
 		});
 
 		LOG("Starting " << PADHEX(2) << int(command_));
@@ -240,6 +259,7 @@ void WD1770::posit_event(int new_event_type) {
 			status.data_request = false;
 		});
 
+		LOG("Step/Seek/Restore with track " << int(track_) << " data " << int(data_));
 		if(!has_motor_on_line() && !has_head_load_line()) goto test_type1_type;
 
 		if(has_motor_on_line()) goto begin_type1_spin_up;
@@ -272,19 +292,19 @@ void WD1770::posit_event(int new_event_type) {
 		}
 
 	perform_seek_or_restore_command:
-		if(track_ == data_) goto verify;
+		if(track_ == data_) goto verify_seek;
 		step_direction_ = (data_ > track_);
 
 	adjust_track:
-		if(step_direction_) track_++; else track_--;
+		if(step_direction_) ++track_; else --track_;
 
 	perform_step:
 		if(!step_direction_ && get_drive().get_is_track_zero()) {
 			track_ = 0;
-			goto verify;
+			goto verify_seek;
 		}
 		get_drive().step(Storage::Disk::HeadPosition(step_direction_ ? 1 : -1));
-		unsigned int time_to_wait;
+		Cycles::IntType time_to_wait;
 		switch(command_ & 3) {
 			default:
 			case 0: time_to_wait = 6;	break;
@@ -293,14 +313,17 @@ void WD1770::posit_event(int new_event_type) {
 			case 3: time_to_wait = (personality_ == P1772) ? 3 : 30;	break;
 		}
 		WAIT_FOR_TIME(time_to_wait);
-		if(command_ >> 5) goto verify;
+		if(command_ >> 5) goto verify_seek;
 		goto perform_seek_or_restore_command;
 
 	perform_step_command:
 		if(command_ & 0x10) goto adjust_track;
 		goto perform_step;
 
-	verify:
+	verify_seek:
+		update_status([this] (Status &status) {
+			status.track_zero = get_drive().get_is_track_zero();
+		});
 		if(!(command_ & 0x04)) {
 			goto wait_for_command;
 		}
@@ -309,17 +332,20 @@ void WD1770::posit_event(int new_event_type) {
 		distance_into_section_ = 0;
 
 	verify_read_data:
-		WAIT_FOR_EVENT(static_cast<int>(Event::IndexHole) | static_cast<int>(Event::Token));
+		WAIT_FOR_EVENT(int(Event::IndexHole) | int(Event::Token));
 		READ_ID();
 
 		if(index_hole_count_ == 6) {
+			LOG("Nothing found to verify");
 			update_status([] (Status &status) {
 				status.seek_error = true;
 			});
 			goto wait_for_command;
 		}
 		if(distance_into_section_ == 7) {
+			distance_into_section_ = 0;
 			set_data_mode(DataMode::Scanning);
+
 			if(get_crc_generator().get_value()) {
 				update_status([] (Status &status) {
 					status.crc_error = true;
@@ -334,8 +360,6 @@ void WD1770::posit_event(int new_event_type) {
 				});
 				goto wait_for_command;
 			}
-
-			distance_into_section_ = 0;
 		}
 		goto verify_read_data;
 
@@ -392,8 +416,11 @@ void WD1770::posit_event(int new_event_type) {
 			goto wait_for_command;
 		}
 
+		distance_into_section_ = 0;
+		set_data_mode(DataMode::Scanning);
+
 	type2_get_header:
-		WAIT_FOR_EVENT(static_cast<int>(Event::IndexHole) | static_cast<int>(Event::Token));
+		WAIT_FOR_EVENT(int(Event::IndexHole) | int(Event::Token));
 		READ_ID();
 
 		if(index_hole_count_ == 5) {
@@ -404,8 +431,10 @@ void WD1770::posit_event(int new_event_type) {
 			goto wait_for_command;
 		}
 		if(distance_into_section_ == 7) {
-			LOG("Considering " << std::dec << int(header_[0]) << "/" << int(header_[2]));
+			distance_into_section_ = 0;
 			set_data_mode(DataMode::Scanning);
+
+			LOG("Considering " << std::dec << int(header_[0]) << "/" << int(header_[2]));
 			if(		header_[0] == track_ && header_[2] == sector_ &&
 					(has_motor_on_line() || !(command_&0x02) || ((command_&0x08) >> 3) == header_[1])) {
 				LOG("Found " << std::dec << int(header_[0]) << "/" << int(header_[2]));
@@ -422,7 +451,6 @@ void WD1770::posit_event(int new_event_type) {
 				});
 				goto type2_read_or_write_data;
 			}
-			distance_into_section_ = 0;
 		}
 		goto type2_get_header;
 
@@ -453,7 +481,7 @@ void WD1770::posit_event(int new_event_type) {
 			status.data_request = true;
 		});
 		distance_into_section_++;
-		if(distance_into_section_ == 128 << header_[3]) {
+		if(distance_into_section_ == 128 << (header_[3]&3)) {
 			distance_into_section_ = 0;
 			goto type2_check_crc;
 		}
@@ -465,6 +493,9 @@ void WD1770::posit_event(int new_event_type) {
 		header_[distance_into_section_] = get_latest_token().byte_value;
 		distance_into_section_++;
 		if(distance_into_section_ == 2) {
+			distance_into_section_ = 0;
+			set_data_mode(DataMode::Scanning);
+
 			if(get_crc_generator().get_value()) {
 				LOG("CRC error; terminating");
 				update_status([this] (Status &status) {
@@ -473,11 +504,13 @@ void WD1770::posit_event(int new_event_type) {
 				goto wait_for_command;
 			}
 
+			LOG("Finished reading sector " << std::dec << int(sector_));
+
 			if(command_ & 0x10) {
 				sector_++;
+				LOG("Advancing to search for sector " << std::dec << int(sector_));
 				goto test_type2_write_protection;
 			}
-			LOG("Finished reading sector " << std::dec << int(sector_));
 			goto wait_for_command;
 		}
 		goto type2_check_crc;
@@ -531,7 +564,7 @@ void WD1770::posit_event(int new_event_type) {
 		*/
 		write_byte(data_);
 		distance_into_section_++;
-		if(distance_into_section_ == 128 << header_[3]) {
+		if(distance_into_section_ == 128 << (header_[3]&3)) {
 			goto type2_write_crc;
 		}
 
@@ -610,8 +643,8 @@ void WD1770::posit_event(int new_event_type) {
 		distance_into_section_ = 0;
 
 	read_address_get_header:
-		WAIT_FOR_EVENT(static_cast<int>(Event::IndexHole) | static_cast<int>(Event::Token));
+		WAIT_FOR_EVENT(int(Event::IndexHole) | int(Event::Token));
-		if(new_event_type == static_cast<int>(Event::Token)) {
+		if(new_event_type == int(Event::Token)) {
 			if(!distance_into_section_ && get_latest_token().type == Token::ID) {set_data_mode(DataMode::Reading); distance_into_section_++; }
 			else if(distance_into_section_ && distance_into_section_ < 7 && get_latest_token().type == Token::Byte) {
 				if(status_.data_request) {
@@ -625,9 +658,11 @@ void WD1770::posit_event(int new_event_type) {
 				update_status([] (Status &status) {
 					status.data_request = true;
 				});
-				distance_into_section_++;
+				++distance_into_section_;
 
 				if(distance_into_section_ == 7) {
+					distance_into_section_ = 0;
+
 					if(get_crc_generator().get_value()) {
 						update_status([] (Status &status) {
 							status.crc_error = true;
@@ -651,7 +686,7 @@ void WD1770::posit_event(int new_event_type) {
 		index_hole_count_ = 0;
 
 	read_track_read_byte:
-		WAIT_FOR_EVENT(static_cast<int>(Event::Token) | static_cast<int>(Event::IndexHole));
+		WAIT_FOR_EVENT(int(Event::Token) | int(Event::IndexHole));
 		if(index_hole_count_) {
 			goto wait_for_command;
 		}
@@ -718,7 +753,7 @@ void WD1770::posit_event(int new_event_type) {
 				case 0xfd: case 0xfe:
 					// clock is 0xc7 = 1010 0000 0010 1010 = 0xa022
 					write_raw_short(
-						static_cast<uint16_t>(
+						uint16_t(
 							0xa022 |
 							((data_ & 0x80) << 7) |
 							((data_ & 0x40) << 6) |
@@ -767,15 +802,18 @@ void WD1770::posit_event(int new_event_type) {
 }
 
 void WD1770::update_status(std::function<void(Status &)> updater) {
+	const Status old_status = status_;
+
 	if(delegate_) {
-		Status old_status = status_;
 		updater(status_);
-		bool did_change =
+		const bool did_change =
 			(status_.busy != old_status.busy) ||
-			(status_.data_request != old_status.data_request);
+			(status_.data_request != old_status.data_request) ||
+			(status_.interrupt_request != old_status.interrupt_request);
 		if(did_change) delegate_->wd1770_did_change_output(this);
-	}
+	} else updater(status_);
-	else updater(status_);
+
+	if(status_.busy != old_status.busy) update_clocking_observer();
 }
 
 void WD1770::set_head_load_request(bool head_load) {}
@@ -783,5 +821,14 @@ void WD1770::set_motor_on(bool motor_on) {}
 
 void WD1770::set_head_loaded(bool head_loaded) {
 	head_is_loaded_ = head_loaded;
-	if(head_loaded) posit_event(static_cast<int>(Event1770::HeadLoad));
+	if(head_loaded) posit_event(int(Event1770::HeadLoad));
+}
+
+bool WD1770::get_head_loaded() {
+	return head_is_loaded_;
+}
+
+ClockingHint::Preference WD1770::preferred_clocking() {
+	if(status_.busy) return ClockingHint::Preference::RealTime;
+	return Storage::Disk::MFMController::preferred_clocking();
 }

Components/1770/1770.hpp

@@ -36,29 +36,29 @@ class WD1770: public Storage::Disk::MFMController {
 		using Storage::Disk::MFMController::set_is_double_density;
 
 		/// Writes @c value to the register at @c address. Only the low two bits of the address are decoded.
-		void set_register(int address, uint8_t value);
+		void write(int address, uint8_t value);
 
 		/// Fetches the value of the register @c address. Only the low two bits of the address are decoded.
-		uint8_t get_register(int address);
+		uint8_t read(int address);
 
 		/// Runs the controller for @c number_of_cycles cycles.
 		void run_for(const Cycles cycles);
 
 		enum Flag: uint8_t {
-			NotReady		= 0x80,
+			NotReady		= 0x80,		// 0x80
 			MotorOn			= 0x80,
-			WriteProtect	= 0x40,
+			WriteProtect	= 0x40,		// 0x40
-			RecordType		= 0x20,
+			RecordType		= 0x20,		// 0x20
 			SpinUp			= 0x20,
 			HeadLoaded		= 0x20,
-			RecordNotFound	= 0x10,
+			RecordNotFound	= 0x10,		// 0x10
 			SeekError		= 0x10,
-			CRCError		= 0x08,
+			CRCError		= 0x08,		// 0x08
-			LostData		= 0x04,
+			LostData		= 0x04,		// 0x04
 			TrackZero		= 0x04,
-			DataRequest		= 0x02,
+			DataRequest		= 0x02,		// 0x02
 			Index			= 0x02,
-			Busy			= 0x01
+			Busy			= 0x01		// 0x01
 		};
 
 		/// @returns The current value of the IRQ line output.
@@ -73,11 +73,16 @@ class WD1770: public Storage::Disk::MFMController {
 		};
 		inline void set_delegate(Delegate *delegate)	{	delegate_ = delegate;			}
 
+		ClockingHint::Preference preferred_clocking() final;
+
 	protected:
 		virtual void set_head_load_request(bool head_load);
 		virtual void set_motor_on(bool motor_on);
 		void set_head_loaded(bool head_loaded);
 
+		/// @returns The last value posted to @c set_head_loaded.
+		bool get_head_loaded();
+
 	private:
 		Personality personality_;
 		inline bool has_motor_on_line() { return (personality_ != P1793 ) && (personality_ != P1773); }
@@ -94,6 +99,7 @@ class WD1770: public Storage::Disk::MFMController {
 			bool data_request = false;
 			bool interrupt_request = false;
 			bool busy = false;
+			bool track_zero = false;
 			enum {
 				One, Two, Three
 			} type = One;
@@ -121,7 +127,7 @@ class WD1770: public Storage::Disk::MFMController {
 		void posit_event(int type);
 		int interesting_event_mask_;
 		int resume_point_ = 0;
-		unsigned int delay_time_ = 0;
+		Cycles::IntType delay_time_ = 0;
 
 		// ID buffer
 		uint8_t header_[6];

Components/5380/ncr5380.cpp

@@ -0,0 +1,312 @@
+//
+//  ncr5380.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 10/08/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#include "ncr5380.hpp"
+
+#include "../../Outputs/Log.hpp"
+
+using namespace NCR::NCR5380;
+using SCSI::Line;
+
+NCR5380::NCR5380(SCSI::Bus &bus, int clock_rate) :
+	bus_(bus),
+	clock_rate_(clock_rate) {
+	device_id_ = bus_.add_device();
+	bus_.add_observer(this);
+}
+
+void NCR5380::write(int address, uint8_t value, bool dma_acknowledge) {
+	switch(address & 7) {
+		case 0:
+//			LOG("[SCSI 0] Set current SCSI bus state to " << PADHEX(2) << int(value));
+			data_bus_ = value;
+
+			if(dma_request_ && dma_operation_ == DMAOperation::Send) {
+//				printf("w %02x\n", value);
+				dma_acknowledge_ = true;
+				dma_request_ = false;
+				update_control_output();
+				bus_.set_device_output(device_id_, bus_output_);
+			}
+		break;
+
+		case 1: {
+//			LOG("[SCSI 1] Initiator command register set: " << PADHEX(2) << int(value));
+			initiator_command_ = value;
+
+			bus_output_ &= ~(Line::Reset | Line::Acknowledge | Line::Busy | Line::SelectTarget | Line::Attention);
+			if(value & 0x80) bus_output_ |= Line::Reset;
+			if(value & 0x08) bus_output_ |= Line::Busy;
+			if(value & 0x04) bus_output_ |= Line::SelectTarget;
+
+			/* bit 5 = differential enable if this were a 5381 */
+
+			test_mode_ = value & 0x40;
+			assert_data_bus_ = value & 0x01;
+			update_control_output();
+		} break;
+
+		case 2:
+//			LOG("[SCSI 2] Set mode: " << PADHEX(2) << int(value));
+			mode_ = value;
+
+			// bit 7: 1 = use block mode DMA mode (if DMA mode is also enabled)
+			// bit 6: 1 = be a SCSI target; 0 = be an initiator
+			// bit 5: 1 = check parity
+			// bit 4: 1 = generate an interrupt if parity checking is enabled and an error is found
+			// bit 3: 1 = generate an interrupt when an EOP is received from the DMA controller
+			// bit 2: 1 = generate an interrupt and reset low 6 bits of register 1 if an unexpected loss of Line::Busy occurs
+			// bit 1: 1 = use DMA mode
+			// bit 0: 1 = begin arbitration mode (device ID should be in register 0)
+			arbitration_in_progress_ = false;
+			switch(mode_ & 0x3) {
+				case 0x0:
+					bus_output_ &= ~SCSI::Line::Busy;
+					dma_request_ = false;
+					set_execution_state(ExecutionState::None);
+				break;
+
+				case 0x1:
+					arbitration_in_progress_ = true;
+					set_execution_state(ExecutionState::WaitingForBusy);
+					lost_arbitration_ = false;
+				break;
+
+				default:
+					assert_data_bus_ = false;
+					set_execution_state(ExecutionState::PerformingDMA);
+					bus_.update_observers();
+				break;
+			}
+			update_control_output();
+		break;
+
+		case 3: {
+//			LOG("[SCSI 3] Set target command: " << PADHEX(2) << int(value));
+			target_command_ = value;
+			update_control_output();
+		} break;
+
+		case 4:
+//			LOG("[SCSI 4] Set select enabled: " << PADHEX(2) << int(value));
+		break;
+
+		case 5:
+//			LOG("[SCSI 5] Start DMA send: " << PADHEX(2) << int(value));
+			dma_operation_ = DMAOperation::Send;
+		break;
+
+		case 6:
+//			LOG("[SCSI 6] Start DMA target receive: " << PADHEX(2) << int(value));
+			dma_operation_ = DMAOperation::TargetReceive;
+		break;
+
+		case 7:
+//			LOG("[SCSI 7] Start DMA initiator receive: " << PADHEX(2) << int(value));
+			dma_operation_ = DMAOperation::InitiatorReceive;
+		break;
+	}
+
+	// Data is output only if the data bus is asserted.
+	if(assert_data_bus_) {
+		bus_output_ = (bus_output_ & ~SCSI::Line::Data) | data_bus_;
+	} else {
+		bus_output_ &= ~SCSI::Line::Data;
+	}
+
+	// In test mode, still nothing is output. Otherwise throw out
+	// the current value of bus_output_.
+	if(test_mode_) {
+		bus_.set_device_output(device_id_, SCSI::DefaultBusState);
+	} else {
+		bus_.set_device_output(device_id_, bus_output_);
+	}
+}
+
+uint8_t NCR5380::read(int address, bool dma_acknowledge) {
+	switch(address & 7) {
+		case 0:
+//			LOG("[SCSI 0] Get current SCSI bus state: " << PADHEX(2) << (bus_.get_state() & 0xff));
+
+			if(dma_request_ && dma_operation_ == DMAOperation::InitiatorReceive) {
+				dma_acknowledge_ = true;
+				dma_request_ = false;
+				update_control_output();
+				bus_.set_device_output(device_id_, bus_output_);
+			}
+		return uint8_t(bus_.get_state());
+
+		case 1:
+//			LOG("[SCSI 1] Initiator command register get: " << (arbitration_in_progress_ ? 'p' : '-') <<  (lost_arbitration_ ? 'l' : '-'));
+		return
+			// Bits repeated as they were set.
+			(initiator_command_ & ~0x60) |
+
+			// Arbitration in progress.
+			(arbitration_in_progress_ ? 0x40 : 0x00) |
+
+			// Lost arbitration.
+			(lost_arbitration_ ? 0x20 : 0x00);
+
+		case 2:
+//			LOG("[SCSI 2] Get mode");
+		return mode_;
+
+		case 3:
+//			LOG("[SCSI 3] Get target command");
+		return target_command_;
+
+		case 4: {
+			const auto bus_state = bus_.get_state();
+			const uint8_t result =
+				((bus_state & Line::Reset)			? 0x80 : 0x00) |
+				((bus_state & Line::Busy)			? 0x40 : 0x00) |
+				((bus_state & Line::Request)		? 0x20 : 0x00) |
+				((bus_state & Line::Message)		? 0x10 : 0x00) |
+				((bus_state & Line::Control)		? 0x08 : 0x00) |
+				((bus_state & Line::Input)			? 0x04 : 0x00) |
+				((bus_state & Line::SelectTarget)	? 0x02 : 0x00) |
+				((bus_state & Line::Parity)			? 0x01 : 0x00);
+//			LOG("[SCSI 4] Get current bus state: " << PADHEX(2) << int(result));
+			return result;
+		}
+
+		case 5: {
+			const auto bus_state = bus_.get_state();
+			const bool phase_matches =
+				(target_output() & (Line::Message | Line::Control | Line::Input)) ==
+				(bus_state & (Line::Message | Line::Control | Line::Input));
+
+			const uint8_t result =
+				/* b7 = end of DMA */
+				((dma_request_ && state_ == ExecutionState::PerformingDMA) ? 0x40 : 0x00)	|
+				/* b5 = parity error */
+				/* b4 = IRQ active */
+				(phase_matches ? 0x08 : 0x00)	|
+				/* b2 = busy error */
+				((bus_state & Line::Attention) ? 0x02 : 0x00) |
+				((bus_state & Line::Acknowledge) ? 0x01 : 0x00);
+//			LOG("[SCSI 5] Get bus and status: " << PADHEX(2) << int(result));
+			return result;
+		}
+
+		case 6:
+//			LOG("[SCSI 6] Get input data");
+		return 0xff;
+
+		case 7:
+//			LOG("[SCSI 7] Reset parity/interrupt");
+		return 0xff;
+	}
+	return 0;
+}
+
+SCSI::BusState NCR5380::target_output() {
+	SCSI::BusState output = SCSI::DefaultBusState;
+	if(target_command_ & 0x08) output |= Line::Request;
+	if(target_command_ & 0x04) output |= Line::Message;
+	if(target_command_ & 0x02) output |= Line::Control;
+	if(target_command_ & 0x01) output |= Line::Input;
+	return output;
+}
+
+void NCR5380::update_control_output() {
+	bus_output_ &= ~(Line::Request | Line::Message | Line::Control | Line::Input | Line::Acknowledge | Line::Attention);
+	if(mode_ & 0x40) {
+		// This is a target; C/D, I/O, /MSG and /REQ are signalled on the bus.
+		bus_output_ |= target_output();
+	} else {
+		// This is an initiator; /ATN and /ACK are signalled on the bus.
+		if(
+			(initiator_command_ & 0x10) ||
+			(state_ == ExecutionState::PerformingDMA && dma_acknowledge_)
+		) bus_output_ |= Line::Acknowledge;
+		if(initiator_command_ & 0x02) bus_output_ |= Line::Attention;
+	}
+}
+
+void NCR5380::scsi_bus_did_change(SCSI::Bus *, SCSI::BusState new_state, double time_since_change) {
+	switch(state_) {
+		default: break;
+
+		/*
+			Official documentation:
+
+				Arbitration is accomplished using a bus-free filter to continuously monitor BSY.
+				If BSY remains inactive for at least 400 nsec then the SCSI bus is considered free
+				and arbitration may begin. Arbitration will begin if the bus is free, SEL is inactive
+				and the ARBITRATION bit (port 2, bit 0) is active. Once arbitration has begun
+				(BSY asserted), an arbitration delay of 2.2 /Lsec must elapse before the data bus
+				can be examined to deter- mine if arbitration has been won. This delay must be
+				implemented in the controlling software driver.
+
+			Personal notes:
+
+				I'm discounting that "arbitratation is accomplished" opening, and assuming that what needs
+				to happen is:
+
+					(i) wait for BSY to be inactive;
+					(ii) count 400 nsec;
+					(iii) check that BSY and SEL are inactive.
+		*/
+
+		case ExecutionState::WaitingForBusy:
+			if(!(new_state & SCSI::Line::Busy) || time_since_change < SCSI::DeskewDelay) return;
+			state_ = ExecutionState::WatchingBusy;
+
+		case ExecutionState::WatchingBusy:
+			if(!(new_state & SCSI::Line::Busy)) {
+				lost_arbitration_ = true;
+				set_execution_state(ExecutionState::None);
+			}
+
+			// Check for having hit 400ns (more or less) since BSY was inactive.
+			if(time_since_change >= SCSI::BusSettleDelay) {
+//				arbitration_in_progress_ = false;
+				if(new_state & SCSI::Line::SelectTarget) {
+					lost_arbitration_ = true;
+					set_execution_state(ExecutionState::None);
+				} else {
+					bus_output_ &= ~SCSI::Line::Busy;
+					set_execution_state(ExecutionState::None);
+				}
+			}
+
+			/* TODO: there's a bug here, given that the dropping of Busy isn't communicated onward. */
+		break;
+
+		case ExecutionState::PerformingDMA:
+			if(time_since_change < SCSI::DeskewDelay) return;
+
+			// Signal a DMA request if the request line is active, i.e. meaningful data is
+			// on the bus, and this device hasn't yet acknowledged it.
+			switch(new_state & (SCSI::Line::Request | SCSI::Line::Acknowledge)) {
+				case 0:
+					dma_request_ = false;
+				break;
+				case SCSI::Line::Request:
+					dma_request_ = true;
+				break;
+				case SCSI::Line::Request | SCSI::Line::Acknowledge:
+					dma_request_ = false;
+				break;
+				case SCSI::Line::Acknowledge:
+					dma_acknowledge_ = false;
+					dma_request_ = false;
+					update_control_output();
+					bus_.set_device_output(device_id_, bus_output_);
+				break;
+			}
+		break;
+	}
+}
+
+void NCR5380::set_execution_state(ExecutionState state) {
+	state_ = state;
+	if(state != ExecutionState::PerformingDMA) dma_operation_ = DMAOperation::Ready;
+}

Components/5380/ncr5380.hpp

@@ -0,0 +1,75 @@
+//
+//  ncr5380.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 10/08/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#ifndef ncr5380_hpp
+#define ncr5380_hpp
+
+#include <cstdint>
+
+#include "../../Storage/MassStorage/SCSI/SCSI.hpp"
+
+
+namespace NCR {
+namespace NCR5380 {
+
+/*!
+	Models the NCR 5380, a SCSI interface chip.
+*/
+class NCR5380 final: public SCSI::Bus::Observer {
+	public:
+		NCR5380(SCSI::Bus &bus, int clock_rate);
+
+		/*! Writes @c value to @c address.  */
+		void write(int address, uint8_t value, bool dma_acknowledge = false);
+
+		/*! Reads from @c address. */
+		uint8_t read(int address, bool dma_acknowledge = false);
+
+	private:
+		SCSI::Bus &bus_;
+
+		const int clock_rate_;
+		size_t device_id_;
+
+		SCSI::BusState bus_output_ = SCSI::DefaultBusState;
+		SCSI::BusState expected_phase_ = SCSI::DefaultBusState;
+		uint8_t mode_ = 0xff;
+		uint8_t initiator_command_ = 0xff;
+		uint8_t data_bus_ = 0xff;
+		uint8_t target_command_ = 0xff;
+		bool test_mode_ = false;
+		bool assert_data_bus_ = false;
+		bool dma_request_ = false;
+		bool dma_acknowledge_ = false;
+
+		enum class ExecutionState {
+			None,
+			WaitingForBusy,
+			WatchingBusy,
+			PerformingDMA,
+		} state_ = ExecutionState::None;
+		enum class DMAOperation {
+			Ready,
+			Send,
+			TargetReceive,
+			InitiatorReceive
+		} dma_operation_ = DMAOperation::Ready;
+		bool lost_arbitration_ = false, arbitration_in_progress_ = false;
+
+		void set_execution_state(ExecutionState state);
+
+		SCSI::BusState target_output();
+		void update_control_output();
+
+		void scsi_bus_did_change(SCSI::Bus *, SCSI::BusState new_state, double time_since_change) final;
+};
+
+}
+}
+
+#endif /* ncr5380_hpp */

Components/6522/6522.hpp

@@ -94,10 +94,10 @@ template <class T> class MOS6522: public MOS6522Storage {
 		MOS6522(const MOS6522 &) = delete;
 
 		/*! Sets a register value. */
-		void set_register(int address, uint8_t value);
+		void write(int address, uint8_t value);
 
 		/*! Gets a register value. */
-		uint8_t get_register(int address);
+		uint8_t read(int address);
 
 		/*! @returns the bus handler. */
 		T &bus_handler();

Components/6522/Implementation/6522Implementation.hpp

@@ -30,7 +30,7 @@ template <typename T> void MOS6522<T>::access(int address) {
 	}
 }
 
-template <typename T> void MOS6522<T>::set_register(int address, uint8_t value) {
+template <typename T> void MOS6522<T>::write(int address, uint8_t value) {
 	address &= 0xf;
 	access(address);
 	switch(address) {
@@ -155,7 +155,7 @@ template <typename T> void MOS6522<T>::set_register(int address, uint8_t value)
 	}
 }
 
-template <typename T> uint8_t MOS6522<T>::get_register(int address) {
+template <typename T> uint8_t MOS6522<T>::read(int address) {
 	address &= 0xf;
 	access(address);
 	switch(address) {
@@ -346,7 +346,7 @@ template <typename T> void MOS6522<T>::do_phase1() {
 
 /*! Runs for a specified number of half cycles. */
 template <typename T> void MOS6522<T>::run_for(const HalfCycles half_cycles) {
-	int number_of_half_cycles = half_cycles.as_int();
+	auto number_of_half_cycles = half_cycles.as_integral();
 	if(!number_of_half_cycles) return;
 
 	if(is_phase2_) {
@@ -375,7 +375,7 @@ template <typename T> void MOS6522<T>::flush() {
 
 /*! Runs for a specified number of cycles. */
 template <typename T> void MOS6522<T>::run_for(const Cycles cycles) {
-	int number_of_cycles = cycles.as_int();
+	auto number_of_cycles = cycles.as_integral();
 	while(number_of_cycles--) {
 		do_phase1();
 		do_phase2();

Components/6532/6532.hpp

@@ -32,7 +32,7 @@ template <class T> class MOS6532 {
 		inline void set_ram(uint16_t address, uint8_t value)	{	ram_[address&0x7f] = value;		}
 		inline uint8_t get_ram(uint16_t address)				{	return ram_[address & 0x7f];	}
 
-		inline void set_register(int address, uint8_t value) {
+		inline void write(int address, uint8_t value) {
 			const uint8_t decodedAddress = address & 0x07;
 			switch(decodedAddress) {
 				// Port output
@@ -63,7 +63,7 @@ template <class T> class MOS6532 {
 			}
 		}
 
-		inline uint8_t get_register(int address) {
+		inline uint8_t read(int address) {
 			const uint8_t decodedAddress = address & 0x7;
 			switch(decodedAddress) {
 				// Port input
@@ -107,7 +107,7 @@ template <class T> class MOS6532 {
 		}
 
 		inline void run_for(const Cycles cycles) {
-			unsigned int number_of_cycles = static_cast<unsigned int>(cycles.as_int());
+			unsigned int number_of_cycles = static_cast<unsigned int>(cycles.as_integral());
 
 			// permit counting _to_ zero; counting _through_ zero initiates the other behaviour
 			if(timer_.value >= number_of_cycles) {

Components/6560/6560.cpp

@@ -17,13 +17,13 @@ AudioGenerator::AudioGenerator(Concurrency::DeferringAsyncTaskQueue &audio_queue
 
 
 void AudioGenerator::set_volume(uint8_t volume) {
-	audio_queue_.defer([=]() {
+	audio_queue_.defer([this, volume]() {
-		volume_ = static_cast<int16_t>(volume) * range_multiplier_;
+		volume_ = int16_t(volume) * range_multiplier_;
 	});
 }
 
 void AudioGenerator::set_control(int channel, uint8_t value) {
-	audio_queue_.defer([=]() {
+	audio_queue_.defer([this, channel, value]() {
 		control_registers_[channel] = value;
 	});
 }

Components/6560/6560.hpp

@@ -30,6 +30,7 @@ class AudioGenerator: public ::Outputs::Speaker::SampleSource {
 		void get_samples(std::size_t number_of_samples, int16_t *target);
 		void skip_samples(std::size_t number_of_samples);
 		void set_sample_volume_range(std::int16_t range);
+		static constexpr bool get_is_stereo() { return false; }
 
 	private:
 		Concurrency::DeferringAsyncTaskQueue &audio_queue_;
@@ -58,7 +59,7 @@ enum class OutputMode {
 	To run the VIC for a cycle, the caller should call @c get_address, make the requested bus access
 	and call @c set_graphics_value with the result.
 
-	@c set_register and @c get_register provide register access.
+	@c write and @c read provide register access.
 */
 template <class BusHandler> class MOS6560 {
 	public:
@@ -84,6 +85,7 @@ template <class BusHandler> class MOS6560 {
 		}
 
 		void set_scan_target(Outputs::Display::ScanTarget *scan_target)		{ crt_.set_scan_target(scan_target); 			}
+		Outputs::Display::ScanStatus get_scaled_scan_status() const			{ return crt_.get_scaled_scan_status() / 4.0f;	}
 		void set_display_type(Outputs::Display::DisplayType display_type)	{ crt_.set_display_type(display_type); 			}
 		Outputs::Speaker::Speaker *get_speaker() { return &speaker_; }
 
@@ -170,7 +172,7 @@ template <class BusHandler> class MOS6560 {
 			// keep track of the amount of time since the speaker was updated; lazy updates are applied
 			cycles_since_speaker_update_ += cycles;
 
-			int number_of_cycles = cycles.as_int();
+			auto number_of_cycles = cycles.as_integral();
 			while(number_of_cycles--) {
 				// keep an old copy of the vertical count because that test is a cycle later than the actual changes
 				int previous_vertical_counter = vertical_counter_;
@@ -353,7 +355,7 @@ template <class BusHandler> class MOS6560 {
 		/*!
 			Writes to a 6560 register.
 		*/
-		void set_register(int address, uint8_t value) {
+		void write(int address, uint8_t value) {
 			address &= 0xf;
 			registers_.direct_values[address] = value;
 			switch(address) {
@@ -417,7 +419,7 @@ template <class BusHandler> class MOS6560 {
 		/*
 			Reads from a 6560 register.
 		*/
-		uint8_t get_register(int address) {
+		uint8_t read(int address) {
 			address &= 0xf;
 			switch(address) {
 				default: return registers_.direct_values[address];

Components/6845/CRTC6845.hpp

@@ -111,7 +111,7 @@ template <class T> class CRTC6845 {
 		}
 
 		void run_for(Cycles cycles) {
-			int cyles_remaining = cycles.as_int();
+			auto cyles_remaining = cycles.as_integral();
 			while(cyles_remaining--) {
 				// check for end of visible characters
 				if(character_counter_ == registers_[1]) {

Components/6850/6850.cpp

@@ -0,0 +1,228 @@
+//
+//  6850.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 10/10/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#include "6850.hpp"
+
+#include <cassert>
+
+using namespace Motorola::ACIA;
+
+const HalfCycles ACIA::SameAsTransmit;
+
+ACIA::ACIA(HalfCycles transmit_clock_rate, HalfCycles receive_clock_rate) :
+	transmit_clock_rate_(transmit_clock_rate),
+	receive_clock_rate_((receive_clock_rate != SameAsTransmit) ? receive_clock_rate : transmit_clock_rate) {
+	transmit.set_writer_clock_rate(transmit_clock_rate);
+	request_to_send.set_writer_clock_rate(transmit_clock_rate);
+}
+
+uint8_t ACIA::read(int address) {
+	if(address&1) {
+		overran_ = false;
+		received_data_ |= NoValueMask;
+		update_interrupt_line();
+		return uint8_t(received_data_);
+	} else {
+		return get_status();
+	}
+}
+
+void ACIA::reset() {
+	transmit.reset_writing();
+	transmit.write(true);
+	request_to_send.reset_writing();
+
+	bits_received_ = bits_incoming_ = 0;
+	receive_interrupt_enabled_ = transmit_interrupt_enabled_ = false;
+	overran_ = false;
+	next_transmission_ = received_data_ = NoValueMask;
+
+	update_interrupt_line();
+	assert(!interrupt_line_);
+}
+
+void ACIA::write(int address, uint8_t value) {
+	if(address&1) {
+		next_transmission_ = value;
+		consider_transmission();
+		update_interrupt_line();
+	} else {
+		if((value&3) == 3) {
+			reset();
+		} else {
+			switch(value & 3) {
+				default:
+				case 0: divider_ = 1;	break;
+				case 1: divider_ = 16;	break;
+				case 2: divider_ = 64;	break;
+			}
+			switch((value >> 2) & 7) {
+				default:
+				case 0:	data_bits_ = 7; stop_bits_ = 2; parity_ = Parity::Even;	break;
+				case 1:	data_bits_ = 7; stop_bits_ = 2; parity_ = Parity::Odd;	break;
+				case 2:	data_bits_ = 7; stop_bits_ = 1; parity_ = Parity::Even;	break;
+				case 3:	data_bits_ = 7; stop_bits_ = 1; parity_ = Parity::Odd;	break;
+				case 4:	data_bits_ = 8; stop_bits_ = 2; parity_ = Parity::None;	break;
+				case 5:	data_bits_ = 8; stop_bits_ = 1; parity_ = Parity::None;	break;
+				case 6:	data_bits_ = 8; stop_bits_ = 1; parity_ = Parity::Even;	break;
+				case 7:	data_bits_ = 8; stop_bits_ = 1; parity_ = Parity::Odd;	break;
+			}
+			switch((value >> 5) & 3) {
+				case 0:	request_to_send.write(false); transmit_interrupt_enabled_ = false;	break;
+				case 1:	request_to_send.write(false); transmit_interrupt_enabled_ = true;	break;
+				case 2:	request_to_send.write(true); transmit_interrupt_enabled_ = false;	break;
+				case 3:
+					request_to_send.write(false);
+					transmit_interrupt_enabled_ = false;
+					transmit.reset_writing();
+					transmit.write(false);
+				break;
+			}
+			receive.set_read_delegate(this, Storage::Time(divider_ * 2, int(receive_clock_rate_.as_integral())));
+			receive_interrupt_enabled_ = value & 0x80;
+
+			update_interrupt_line();
+		}
+	}
+	update_clocking_observer();
+}
+
+void ACIA::consider_transmission() {
+	if(next_transmission_ != NoValueMask && !transmit.write_data_time_remaining()) {
+		// Establish start bit and [7 or 8] data bits.
+		if(data_bits_ == 7) next_transmission_ &= 0x7f;
+		int transmission = next_transmission_ << 1;
+
+		// Add a parity bit, if any.
+		int mask = 0x2 << data_bits_;
+		if(parity_ != Parity::None) {
+			transmission |= parity(uint8_t(next_transmission_)) ? mask : 0;
+			mask <<= 1;
+		}
+
+		// Add stop bits.
+		for(int c = 0; c < stop_bits_; ++c) {
+			transmission |= mask;
+			mask <<= 1;
+		}
+
+		// Output all that.
+		const int total_bits = expected_bits();
+		transmit.write(divider_ * 2, total_bits, transmission);
+
+		// Mark the transmit register as empty again.
+		next_transmission_ = NoValueMask;
+	}
+}
+
+ClockingHint::Preference ACIA::preferred_clocking() {
+	// Real-time clocking is required if a transmission is ongoing; this is a courtesy for whomever
+	// is on the receiving end.
+	if(transmit.transmission_data_time_remaining() > 0) return ClockingHint::Preference::RealTime;
+
+	// If a bit reception is ongoing that might lead to an interrupt, ask for real-time clocking
+	// because it's unclear when the interrupt might come.
+	if(bits_incoming_ && receive_interrupt_enabled_) return ClockingHint::Preference::RealTime;
+
+	// No clocking required then.
+	return ClockingHint::Preference::None;
+}
+
+bool ACIA::get_interrupt_line() const {
+	return interrupt_line_;
+}
+
+int ACIA::expected_bits() {
+	return 1 + data_bits_ + stop_bits_ + (parity_ != Parity::None);
+}
+
+uint8_t ACIA::parity(uint8_t value) {
+	value ^= value >> 4;
+	value ^= value >> 2;
+	value ^= value >> 1;
+	return value ^ (parity_ == Parity::Even);
+}
+
+bool ACIA::serial_line_did_produce_bit(Serial::Line *line, int bit) {
+	// Shift this bit into the 11-bit input register; this is big enough to hold
+	// the largest transmission symbol.
+	++bits_received_;
+	bits_incoming_ = (bits_incoming_ >> 1) | (bit << 10);
+
+	// If that's the now-expected number of bits, update.
+	const int bit_target = expected_bits();
+	if(bits_received_ >= bit_target) {
+		bits_received_ = 0;
+		overran_ |= get_status() & 1;
+		received_data_ = uint8_t(bits_incoming_ >> (12 - bit_target));
+		update_interrupt_line();
+		update_clocking_observer();
+		return false;
+	}
+
+	// TODO: overrun, and parity.
+
+	// Keep receiving, and consider a potential clocking change.
+	if(bits_received_ == 1) update_clocking_observer();
+	return true;
+}
+
+void ACIA::set_interrupt_delegate(InterruptDelegate *delegate) {
+	interrupt_delegate_ = delegate;
+}
+
+void ACIA::update_interrupt_line() {
+	const bool old_line = interrupt_line_;
+
+	/*
+		"Bit 7 of the control register is the rie bit. When the rie bit is high, the rdrf, ndcd,
+		and ovr bits will assert the nirq output. When the rie bit is low, nirq generation is disabled."
+
+		rie = read interrupt enable
+		rdrf = receive data register full (status word bit 0)
+		ndcd = data carrier detect (status word bit 2)
+		over = receiver overrun (status word bit 5)
+
+		"Bit 1 of the status register is the tdre bit. When high, the tdre bit indicates that data has been
+		transferred from the transmitter data register to the output shift register. At this point, the a6850
+		is ready to accept a new transmit data byte. However, if the ncts signal is high, the tdre bit remains
+		low regardless of the status of the transmitter data register. Also, if transmit interrupt is enabled,
+		the nirq output is asserted."
+
+		tdre = transmitter data register empty
+		ncts = clear to send
+	*/
+	const auto status = get_status();
+	interrupt_line_ =
+		(receive_interrupt_enabled_ && (status & 0x25)) ||
+		(transmit_interrupt_enabled_ && (status & 0x02));
+
+	if(interrupt_delegate_ && old_line != interrupt_line_) {
+		interrupt_delegate_->acia6850_did_change_interrupt_status(this);
+	}
+}
+
+uint8_t ACIA::get_status() {
+	return
+		((received_data_ & NoValueMask) ? 0x00 : 0x01) |
+		((next_transmission_ == NoValueMask) ? 0x02 : 0x00) |
+//		(data_carrier_detect.read() ? 0x04 : 0x00) |
+//		(clear_to_send.read() ? 0x08 : 0x00) |
+		(overran_ ? 0x20 : 0x00) |
+		(interrupt_line_ ? 0x80 : 0x00)
+	;
+
+	// b0: receive data full.
+	// b1: transmit data empty.
+	// b2: DCD.
+	// b3: CTS.
+	// b4: framing error (i.e. no first stop bit where expected).
+	// b5: receiver overran.
+	// b6: parity error.
+	// b7: IRQ state.
+}

Components/6850/6850.hpp

@@ -0,0 +1,132 @@
+//
+//  6850.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 10/10/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#ifndef Motorola_ACIA_6850_hpp
+#define Motorola_ACIA_6850_hpp
+
+#include <cstdint>
+#include "../../ClockReceiver/ClockReceiver.hpp"
+#include "../../ClockReceiver/ForceInline.hpp"
+#include "../../ClockReceiver/ClockingHintSource.hpp"
+#include "../Serial/Line.hpp"
+
+namespace Motorola {
+namespace ACIA {
+
+class ACIA: public ClockingHint::Source, private Serial::Line::ReadDelegate {
+	public:
+		static constexpr const HalfCycles SameAsTransmit = HalfCycles(0);
+
+		/*!
+			Constructs a new instance of ACIA which will receive a transmission clock at a rate of
+			@c transmit_clock_rate, and a receive clock at a rate of @c receive_clock_rate.
+		*/
+		ACIA(HalfCycles transmit_clock_rate, HalfCycles receive_clock_rate = SameAsTransmit);
+
+		/*!
+			Reads from the ACIA.
+
+			Bit 0 of the address is used as the ACIA's register select line —
+			so even addresses select control/status registers, odd addresses
+			select transmit/receive data registers.
+		*/
+		uint8_t read(int address);
+
+		/*!
+			Writes to the ACIA.
+
+			Bit 0 of the address is used as the ACIA's register select line —
+			so even addresses select control/status registers, odd addresses
+			select transmit/receive data registers.
+		*/
+		void write(int address, uint8_t value);
+
+		/*!
+			Advances @c transmission_cycles in time, which should be
+			counted relative to the @c transmit_clock_rate.
+		*/
+		forceinline void run_for(HalfCycles transmission_cycles) {
+			if(transmit.transmission_data_time_remaining() > HalfCycles(0)) {
+				const auto write_data_time_remaining = transmit.write_data_time_remaining();
+
+				// There's at most one further byte available to enqueue, so a single 'if'
+				// rather than a 'while' is correct here. It's the responsibilit of the caller
+				// to ensure run_for lengths are appropriate for longer sequences.
+				if(transmission_cycles >= write_data_time_remaining) {
+					if(next_transmission_ != NoValueMask) {
+						transmit.advance_writer(write_data_time_remaining);
+						consider_transmission();
+						transmit.advance_writer(transmission_cycles - write_data_time_remaining);
+					} else {
+						transmit.advance_writer(transmission_cycles);
+						update_clocking_observer();
+						update_interrupt_line();
+					}
+				} else {
+					transmit.advance_writer(transmission_cycles);
+				}
+			}
+		}
+
+		bool get_interrupt_line() const;
+		void reset();
+
+		// Input lines.
+		Serial::Line receive;
+		Serial::Line clear_to_send;
+		Serial::Line data_carrier_detect;
+
+		// Output lines.
+		Serial::Line transmit;
+		Serial::Line request_to_send;
+
+		// ClockingHint::Source.
+		ClockingHint::Preference preferred_clocking() final;
+
+		struct InterruptDelegate {
+			virtual void acia6850_did_change_interrupt_status(ACIA *acia) = 0;
+		};
+		void set_interrupt_delegate(InterruptDelegate *delegate);
+
+	private:
+		int divider_ = 1;
+		enum class Parity {
+			Even, Odd, None
+		} parity_ = Parity::None;
+		int data_bits_ = 7, stop_bits_ = 2;
+
+		static constexpr int NoValueMask = 0x100;
+		int next_transmission_ = NoValueMask;
+		int received_data_ = NoValueMask;
+
+		int bits_received_ = 0;
+		int bits_incoming_ = 0;
+		bool overran_ = false;
+
+		void consider_transmission();
+		int expected_bits();
+		uint8_t parity(uint8_t value);
+
+		bool receive_interrupt_enabled_ = false;
+		bool transmit_interrupt_enabled_ = false;
+
+		HalfCycles transmit_clock_rate_;
+		HalfCycles receive_clock_rate_;
+
+		bool serial_line_did_produce_bit(Serial::Line *line, int bit) final;
+
+		bool interrupt_line_ = false;
+		void update_interrupt_line();
+		InterruptDelegate *interrupt_delegate_ = nullptr;
+		uint8_t get_status();
+};
+
+}
+}
+
+#endif /* Motorola_ACIA_6850_hpp */

Components/68901/MFP68901.cpp

@@ -0,0 +1,374 @@
+//
+//  MFP68901.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 06/10/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#include "MFP68901.hpp"
+
+#include <algorithm>
+#include <cstring>
+
+#ifndef NDEBUG
+#define NDEBUG
+#endif
+
+#define LOG_PREFIX "[MFP] "
+#include "../../Outputs/Log.hpp"
+
+using namespace Motorola::MFP68901;
+
+ClockingHint::Preference MFP68901::preferred_clocking() {
+	// Rule applied: if any timer is actively running and permitted to produce an
+	// interrupt, request real-time running.
+	return
+		(timers_[0].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerA) ||
+		(timers_[1].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerB) ||
+		(timers_[2].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerC) ||
+		(timers_[3].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerD)
+			? ClockingHint::Preference::RealTime : ClockingHint::Preference::JustInTime;
+}
+
+uint8_t MFP68901::read(int address) {
+	address &= 0x1f;
+
+	// Interrupt block: various bits of state can be read, all passively.
+	if(address >= 0x03 && address <= 0x0b) {
+		const int shift = (address&1) << 3;
+		switch(address) {
+			case 0x03:	case 0x04:	return uint8_t(interrupt_enable_ >> shift);
+			case 0x05:	case 0x06:	return uint8_t(interrupt_pending_ >> shift);
+			case 0x07:	case 0x08:	return uint8_t(interrupt_in_service_ >> shift);
+			case 0x09:	case 0x0a:	return uint8_t(interrupt_mask_ >> shift);
+			case 0x0b:	return interrupt_vector_;
+
+			default: break;
+		}
+	}
+
+	switch(address) {
+		// GPIP block: input, and configured active edge and direction values.
+		case 0x00:	return (gpip_input_ & ~gpip_direction_) | (gpip_output_ & gpip_direction_);
+		case 0x01:	return gpip_active_edge_;
+		case 0x02:	return gpip_direction_;
+
+		/* Interrupt block dealt with above. */
+		default: break;
+
+		// Timer block: read back A, B and C/D control, and read current timer values.
+		case 0x0c:	case 0x0d:	return timer_ab_control_[address - 0xc];
+		case 0x0e:				return timer_cd_control_;
+		case 0x0f:	case 0x10:
+		case 0x11:	case 0x12:	return get_timer_data(address - 0xf);
+
+		// USART block: TODO.
+		case 0x13:		LOG("Read: sync character generator");	break;
+		case 0x14:		LOG("Read: USART control");				break;
+		case 0x15:		LOG("Read: receiver status");			break;
+		case 0x16:		LOG("Read: transmitter status");		break;
+		case 0x17:		LOG("Read: USART data");				break;
+	}
+	return 0x00;
+}
+
+void MFP68901::write(int address, uint8_t value) {
+	address &= 0x1f;
+
+	// Interrupt block: enabled and masked interrupts can be set; pending and in-service interrupts can be masked.
+	if(address >= 0x03 && address <= 0x0b) {
+		const int shift = (address&1) << 3;
+		const int preserve = 0xff00 >> shift;
+		const int word_value = value << shift;
+
+		switch(address) {
+			default: break;
+			case 0x03: case 0x04:	// Adjust enabled interrupts; disabled ones also cease to be pending.
+				interrupt_enable_ = (interrupt_enable_ & preserve) | word_value;
+				interrupt_pending_ &= interrupt_enable_;
+			break;
+			case 0x05: case 0x06:	// Resolve pending interrupts.
+				interrupt_pending_ &= (preserve | word_value);
+			break;
+			case 0x07: case 0x08:	// Resolve in-service interrupts.
+				interrupt_in_service_ &= (preserve | word_value);
+			break;
+			case 0x09: case 0x0a:	// Adjust interrupt mask.
+				interrupt_mask_ = (interrupt_mask_ & preserve) | word_value;
+			break;
+			case 0x0b:				// Set the interrupt vector, possibly changing end-of-interrupt mode.
+				interrupt_vector_ = value;
+
+				// If automatic end-of-interrupt mode has now been enabled, clear
+				// the in-process mask and re-evaluate.
+				if(interrupt_vector_ & 0x08) return;
+				interrupt_in_service_ = 0;
+			break;
+		}
+
+		// Whatever just happened may have affected the state of the interrupt line.
+		update_interrupts();
+		update_clocking_observer();
+		return;
+	}
+
+	constexpr int timer_prescales[] = {
+		1, 4, 10, 16, 50, 64, 100, 200
+	};
+
+	switch(address) {
+		// GPIP block: output and configuration of active edge and direction values.
+		case 0x00:
+			gpip_output_ = value;
+		break;
+		case 0x01:
+			gpip_active_edge_ = value;
+			reevaluate_gpip_interrupts();
+		break;
+		case 0x02:
+			gpip_direction_ = value;
+			reevaluate_gpip_interrupts();
+		break;
+
+		/* Interrupt block dealt with above. */
+		default: break;
+
+		// Timer block.
+		case 0x0c:
+		case 0x0d: {
+			const auto timer = address - 0xc;
+			const bool reset = value & 0x10;
+			timer_ab_control_[timer] = value;
+			switch(value & 0xf) {
+				case 0x0:	set_timer_mode(timer, TimerMode::Stopped, 1, reset);		break;
+				case 0x1:	set_timer_mode(timer, TimerMode::Delay, 4, reset);			break;
+				case 0x2:	set_timer_mode(timer, TimerMode::Delay, 10, reset);			break;
+				case 0x3:	set_timer_mode(timer, TimerMode::Delay, 16, reset);			break;
+				case 0x4:	set_timer_mode(timer, TimerMode::Delay, 50, reset);			break;
+				case 0x5:	set_timer_mode(timer, TimerMode::Delay, 64, reset);			break;
+				case 0x6:	set_timer_mode(timer, TimerMode::Delay, 100, reset);		break;
+				case 0x7:	set_timer_mode(timer, TimerMode::Delay, 200, reset);		break;
+				case 0x8:	set_timer_mode(timer, TimerMode::EventCount, 1, reset);		break;
+				case 0x9:	set_timer_mode(timer, TimerMode::PulseWidth, 4, reset);		break;
+				case 0xa:	set_timer_mode(timer, TimerMode::PulseWidth, 10, reset);	break;
+				case 0xb:	set_timer_mode(timer, TimerMode::PulseWidth, 16, reset);	break;
+				case 0xc:	set_timer_mode(timer, TimerMode::PulseWidth, 50, reset);	break;
+				case 0xd:	set_timer_mode(timer, TimerMode::PulseWidth, 64, reset);	break;
+				case 0xe:	set_timer_mode(timer, TimerMode::PulseWidth, 100, reset);	break;
+				case 0xf:	set_timer_mode(timer, TimerMode::PulseWidth, 200, reset);	break;
+			}
+		} break;
+		case 0x0e:
+			timer_cd_control_ = value;
+			set_timer_mode(3, (value & 7) ? TimerMode::Delay : TimerMode::Stopped, timer_prescales[value & 7], false);
+			set_timer_mode(2, ((value >> 4) & 7) ? TimerMode::Delay : TimerMode::Stopped, timer_prescales[(value >> 4) & 7], false);
+		break;
+		case 0x0f:	case 0x10:	case 0x11:	case 0x12:
+			set_timer_data(address - 0xf, value);
+		break;
+
+		// USART block: TODO.
+		case 0x13:		LOG("Write: sync character generator");	break;
+		case 0x14:		LOG("Write: USART control");			break;
+		case 0x15:		LOG("Write: receiver status");			break;
+		case 0x16:		LOG("Write: transmitter status");		break;
+		case 0x17:		LOG("Write: USART data");				break;
+	}
+
+	update_clocking_observer();
+}
+
+void MFP68901::run_for(HalfCycles time) {
+	cycles_left_ += time;
+
+	const int cycles = int(cycles_left_.flush<Cycles>().as_integral());
+	if(!cycles) return;
+
+	for(int c = 0; c < 4; ++c) {
+		if(timers_[c].mode >= TimerMode::Delay) {
+			// This code applies the timer prescaling only. prescale_count is used to count
+			// upwards rather than downwards for simplicity, but on the real hardware it's
+			// pretty safe to assume it actually counted downwards. So the clamp to 0 is
+			// because gymnastics may need to occur when the prescale value is altered, e.g.
+			// if a prescale of 256 is set and the prescale_count is currently 2 then the
+			// counter should roll over in 254 cycles. If the user at that point changes the
+			// prescale_count to 1 then the counter will need to be altered to -253 and
+			// allowed to keep counting up until it crosses both 0 and 1.
+			const int dividend = timers_[c].prescale_count + cycles;
+			const int decrements = std::max(dividend / timers_[c].prescale, 0);
+			if(decrements) {
+				decrement_timer(c, decrements);
+				timers_[c].prescale_count = dividend % timers_[c].prescale;
+			} else {
+				timers_[c].prescale_count += cycles;
+			}
+		}
+	}
+}
+
+HalfCycles MFP68901::get_next_sequence_point() {
+	return HalfCycles(-1);
+}
+
+// MARK: - Timers
+
+void MFP68901::set_timer_mode(int timer, TimerMode mode, int prescale, bool reset_timer) {
+	LOG("Timer " << timer << " mode set: " << int(mode) << "; prescale: " << prescale);
+	timers_[timer].mode = mode;
+	if(reset_timer) {
+		timers_[timer].prescale_count = 0;
+		timers_[timer].value = timers_[timer].reload_value;
+	} else {
+		// This hoop is because the prescale_count here goes upward but I'm assuming it goes downward in
+		// real hardware. Therefore this deals with the "switched to a lower prescaling" case whereby the
+		// old cycle should be allowed naturally to expire.
+		timers_[timer].prescale_count = prescale - (timers_[timer].prescale - timers_[timer].prescale_count);
+	}
+
+	timers_[timer].prescale = prescale;
+}
+
+void MFP68901::set_timer_data(int timer, uint8_t value) {
+	if(timers_[timer].mode == TimerMode::Stopped) {
+		timers_[timer].value = value;
+	}
+	timers_[timer].reload_value = value;
+}
+
+uint8_t MFP68901::get_timer_data(int timer) {
+	return timers_[timer].value;
+}
+
+void MFP68901::set_timer_event_input(int channel, bool value) {
+	if(timers_[channel].event_input == value) return;
+
+	timers_[channel].event_input = value;
+	if(timers_[channel].mode == TimerMode::EventCount && (value == !!(gpip_active_edge_ & (0x10 >> channel)))) {
+		// "The active state of the signal on TAI or TBI is dependent upon the associated
+		// Interrupt Channel’s edge bit (GPIP 4 for TAI and GPIP 3 for TBI [...] ).
+		// If the edge bit associated with the TAI or TBI input is a one, it will be active high.
+		decrement_timer(channel, 1);
+	}
+
+	// TODO:
+	//
+	// Altering the edge bit while the timer is in the event count mode can produce a count pulse.
+	// The interrupt channel associated with the input (I3 for I4 for TAI) is allowed to function normally.
+	// To count transitions reliably, the input must remain in each state (1/O) for a length of time equal
+	// to four periods of the timer clock.
+	//
+	// (the final bit probably explains 13 cycles of the DE to interrupt latency; not sure about the other ~15)
+}
+
+void MFP68901::decrement_timer(int timer, int amount) {
+	while(amount--) {
+		--timers_[timer].value;
+		if(timers_[timer].value < 1) {
+			switch(timer) {
+				case 0: begin_interrupts(Interrupt::TimerA);	break;
+				case 1: begin_interrupts(Interrupt::TimerB);	break;
+				case 2: begin_interrupts(Interrupt::TimerC);	break;
+				case 3: begin_interrupts(Interrupt::TimerD);	break;
+			}
+
+			// Re: reloading when in event counting mode; I found the data sheet thoroughly unclear on
+			// this, but it appears empirically to be correct. See e.g. Pompey Pirates menu 27.
+			if(timers_[timer].mode == TimerMode::Delay || timers_[timer].mode == TimerMode::EventCount) {
+				timers_[timer].value += timers_[timer].reload_value;	// TODO: properly.
+			}
+		}
+	}
+}
+
+// MARK: - GPIP
+void MFP68901::set_port_input(uint8_t input) {
+	gpip_input_ = input;
+	reevaluate_gpip_interrupts();
+}
+
+uint8_t MFP68901::get_port_output() {
+	return 0xff;	// TODO.
+}
+
+void MFP68901::reevaluate_gpip_interrupts() {
+	const uint8_t gpip_state = (gpip_input_ & ~gpip_direction_) ^ gpip_active_edge_;
+
+	// An interrupt is detected on any falling edge.
+	const uint8_t new_interrupt_mask = (gpip_state ^ gpip_interrupt_state_) & gpip_interrupt_state_;
+	if(new_interrupt_mask) {
+		begin_interrupts(
+			(new_interrupt_mask & 0x0f) |
+			((new_interrupt_mask & 0x30) << 2) |
+			((new_interrupt_mask & 0xc0) << 8)
+		);
+	}
+	gpip_interrupt_state_ = gpip_state;
+}
+
+// MARK: - Interrupts
+
+void MFP68901::begin_interrupts(int interrupt) {
+	interrupt_pending_ |= interrupt & interrupt_enable_;
+	update_interrupts();
+}
+
+void MFP68901::end_interrupts(int interrupt) {
+	interrupt_pending_ &= ~interrupt;
+	update_interrupts();
+}
+
+void MFP68901::update_interrupts() {
+	const auto old_interrupt_line = interrupt_line_;
+	const auto firing_interrupts = interrupt_pending_ & interrupt_mask_;
+
+	if(!firing_interrupts) {
+		interrupt_line_ = false;
+	} else {
+		if(interrupt_vector_ & 0x8) {
+			// Software interrupt mode: permit only if neither this interrupt
+			// nor a higher interrupt is currently in service.
+			const int highest_bit = msb16(firing_interrupts);
+			interrupt_line_ = !(interrupt_in_service_ & ~(highest_bit + highest_bit - 1));
+		} else {
+			// Auto-interrupt mode; just signal.
+			interrupt_line_ = true;
+		}
+	}
+
+	// Update the delegate if necessary.
+	if(interrupt_delegate_ && interrupt_line_ != old_interrupt_line) {
+		interrupt_delegate_->mfp68901_did_change_interrupt_status(this);
+	}
+}
+
+bool MFP68901::get_interrupt_line() {
+	return interrupt_line_;
+}
+
+int MFP68901::acknowledge_interrupt() {
+	if(!(interrupt_pending_ & interrupt_mask_)) {
+		return NoAcknowledgement;
+	}
+
+	const int mask = msb16(interrupt_pending_ & interrupt_mask_);
+
+	// Clear the pending bit regardless.
+	interrupt_pending_ &= ~mask;
+
+	// If this is software interrupt mode, set the in-service bit.
+	if(interrupt_vector_ & 0x8) {
+		interrupt_in_service_ |= mask;
+	}
+
+	update_interrupts();
+
+	int selected = 0;
+	while((1 << selected) != mask) ++selected;
+//	LOG("Interrupt acknowledged: " << selected);
+	return (interrupt_vector_ & 0xf0) | uint8_t(selected);
+}
+
+void MFP68901::set_interrupt_delegate(InterruptDelegate *delegate) {
+	interrupt_delegate_ = delegate;
+}

Components/68901/MFP68901.hpp

@@ -0,0 +1,187 @@
+//
+//  MFP68901.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 06/10/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#ifndef MFP68901_hpp
+#define MFP68901_hpp
+
+#include <cstdint>
+#include "../../ClockReceiver/ClockReceiver.hpp"
+#include "../../ClockReceiver/ClockingHintSource.hpp"
+
+namespace Motorola {
+namespace MFP68901 {
+
+class PortHandler {
+	public:
+		// TODO: announce changes in output.
+};
+
+/*!
+	Models the Motorola 68901 Multi-Function Peripheral ('MFP').
+*/
+class MFP68901: public ClockingHint::Source {
+	public:
+		/// @returns the result of a read from @c address.
+		uint8_t read(int address);
+
+		/// Performs a write of @c value to @c address.
+		void write(int address, uint8_t value);
+
+		/// Advances the MFP by the supplied number of HalfCycles.
+		void run_for(HalfCycles);
+
+		/// @returns the number of cycles until the next possible sequence point — the next time
+		/// at which the interrupt line _might_ change. This object conforms to ClockingHint::Source
+		/// so that mechanism can also be used to reduce the quantity of calls into this class.
+		///
+		/// @discussion TODO, alas.
+		HalfCycles get_next_sequence_point();
+
+		/// Sets the current level of either of the timer event inputs — TAI and TBI in datasheet terms.
+		void set_timer_event_input(int channel, bool value);
+
+		/// Sets a port handler, a receiver that will be notified upon any change in GPIP output.
+		///
+		/// @discussion TODO.
+		void set_port_handler(PortHandler *);
+
+		/// Sets the current input GPIP values.
+		void set_port_input(uint8_t);
+
+		/// @returns the current GPIP output values.
+		///
+		/// @discussion TODO.
+		uint8_t get_port_output();
+
+		/// @returns @c true if the interrupt output is currently active; @c false otherwise.s
+		bool get_interrupt_line();
+
+		static constexpr int NoAcknowledgement = 0x100;
+
+		/// Communicates an interrupt acknowledge cycle.
+		///
+		/// @returns the vector placed on the bus if any; @c NoAcknowledgement if nothing is loaded.
+		int acknowledge_interrupt();
+
+		struct InterruptDelegate {
+			/// Informs the delegate of a change in the interrupt line of the nominated MFP.
+			virtual void mfp68901_did_change_interrupt_status(MFP68901 *) = 0;
+		};
+		/// Sets a delegate that will be notified upon any change in the interrupt line.
+		void set_interrupt_delegate(InterruptDelegate *delegate);
+
+		// ClockingHint::Source.
+		ClockingHint::Preference preferred_clocking() final;
+
+	private:
+		// MARK: - Timers
+		enum class TimerMode {
+			Stopped, EventCount, Delay, PulseWidth
+		};
+		void set_timer_mode(int timer, TimerMode, int prescale, bool reset_timer);
+		void set_timer_data(int timer, uint8_t);
+		uint8_t get_timer_data(int timer);
+		void decrement_timer(int timer, int amount);
+
+		struct Timer {
+			TimerMode mode = TimerMode::Stopped;
+			uint8_t value = 0;
+			uint8_t reload_value = 0;
+			int prescale = 1;
+			int prescale_count = 1;
+			bool event_input = false;
+		} timers_[4];
+		uint8_t timer_ab_control_[2] = { 0, 0 };
+		uint8_t timer_cd_control_ = 0;
+
+		HalfCycles cycles_left_;
+
+		// MARK: - GPIP
+		uint8_t gpip_input_ = 0;
+		uint8_t gpip_output_ = 0;
+		uint8_t gpip_active_edge_ = 0;
+		uint8_t gpip_direction_ = 0;
+		uint8_t gpip_interrupt_state_ = 0;
+
+		void reevaluate_gpip_interrupts();
+
+		// MARK: - Interrupts
+
+		InterruptDelegate *interrupt_delegate_ = nullptr;
+
+		// Ad hoc documentation:
+		//
+		// An interrupt becomes pending if it is enabled at the time it occurs.
+		//
+		// If a pending interrupt is enabled in the interrupt mask, a processor
+		// interrupt is generated. Otherwise no processor interrupt is generated.
+		//
+		// (Disabling a bit in the enabled mask also instantaneously clears anything
+		// in the pending mask.)
+		//
+		// The user can write to the pending interrupt register; a write
+		// masks whatever is there — so you can disable bits but you cannot set them.
+		//
+		// If the vector register's 'S' bit is set then software end-of-interrupt mode applies:
+		// Acknowledgement of an interrupt clears that interrupt's pending bit, but also sets
+		// its in-service bit. That bit will remain set until the user writes a zero to its position.
+		// If any bits are set in the in-service register, then they will prevent lower-priority
+		// interrupts from being signalled to the CPU. Further interrupts of the same or a higher
+		// priority may occur.
+		//
+		// If the vector register's 'S' bit is clear then automatic end-of-interrupt mode applies:
+		// Acknowledgement of an interrupt will automatically clear the corresponding
+		// pending bit.
+		//
+		int interrupt_enable_ = 0;
+		int interrupt_pending_ = 0;
+		int interrupt_mask_ = 0;
+		int interrupt_in_service_ = 0;
+		bool interrupt_line_ = false;
+		uint8_t interrupt_vector_ = 0;
+
+		enum Interrupt {
+			GPIP0				= (1 << 0),
+			GPIP1				= (1 << 1),
+			GPIP2				= (1 << 2),
+			GPIP3				= (1 << 3),
+			TimerD				= (1 << 4),
+			TimerC				= (1 << 5),
+			GPIP4				= (1 << 6),
+			GPIP5				= (1 << 7),
+
+			TimerB				= (1 << 8),
+			TransmitError		= (1 << 9),
+			TransmitBufferEmpty	= (1 << 10),
+			ReceiveError		= (1 << 11),
+			ReceiveBufferFull	= (1 << 12),
+			TimerA				= (1 << 13),
+			GPIP6				= (1 << 14),
+			GPIP7				= (1 << 15),
+		};
+		void begin_interrupts(int interrupt);
+		void end_interrupts(int interrupt);
+		void update_interrupts();
+
+		/// @returns the most significant bit set in v, assuming it is one of the least significant 16.
+		inline static int msb16(int v) {
+			// Saturate all bits below the MSB.
+			v |= v >> 1;
+			v |= v >> 2;
+			v |= v >> 4;
+			v |= v >> 8;
+
+			// Throw away lesser bits.
+			return (v+1) >> 1;
+		}
+};
+
+}
+}
+
+#endif /* MFP68901_hpp */

Components/8255/i8255.hpp

@@ -27,7 +27,7 @@ template <class T> class i8255 {
 			Stores the value @c value to the register at @c address. If this causes a change in 8255 output
 			then the PortHandler will be informed.
 		*/
-		void set_register(int address, uint8_t value) {
+		void write(int address, uint8_t value) {
 			switch(address & 3) {
 				case 0:
 					if(!(control_ & 0x10)) {
@@ -60,7 +60,7 @@ template <class T> class i8255 {
 			Obtains the current value for the register at @c address. If this provides a reading
 			of input then the PortHandler will be queried.
 		*/
-		uint8_t get_register(int address) {
+		uint8_t read(int address) {
 			switch(address & 3) {
 				case 0:	return (control_ & 0x10) ? port_handler_.get_value(0) : outputs_[0];
 				case 1:	return (control_ & 0x02) ? port_handler_.get_value(1) : outputs_[1];

Components/8272/i8272.cpp

@@ -95,11 +95,11 @@ void i8272::run_for(Cycles cycles) {
 
 	// check for an expired timer
 	if(delay_time_ > 0) {
-		if(cycles.as_int() >= delay_time_) {
+		if(cycles.as_integral() >= delay_time_) {
 			delay_time_ = 0;
 			posit_event(static_cast<int>(Event8272::Timer));
 		} else {
-			delay_time_ -= cycles.as_int();
+			delay_time_ -= cycles.as_integral();
 		}
 	}
 
@@ -108,8 +108,8 @@ void i8272::run_for(Cycles cycles) {
 		int drives_left = drives_seeking_;
 		for(int c = 0; c < 4; c++) {
 			if(drives_[c].phase == Drive::Seeking) {
-				drives_[c].step_rate_counter += cycles.as_int();
+				drives_[c].step_rate_counter += cycles.as_integral();
-				int steps = drives_[c].step_rate_counter / (8000 * step_rate_time_);
+				auto steps = drives_[c].step_rate_counter / (8000 * step_rate_time_);
 				drives_[c].step_rate_counter %= (8000 * step_rate_time_);
 				while(steps--) {
 					// Perform a step.
@@ -141,12 +141,12 @@ void i8272::run_for(Cycles cycles) {
 			int head = c&1;
 
 			if(drives_[drive].head_unload_delay[head] > 0) {
-				if(cycles.as_int() >= drives_[drive].head_unload_delay[head]) {
+				if(cycles.as_integral() >= drives_[drive].head_unload_delay[head]) {
 					drives_[drive].head_unload_delay[head] = 0;
 					drives_[drive].head_is_loaded[head] = false;
 					head_timers_running_--;
 				} else {
-					drives_[drive].head_unload_delay[head] -= cycles.as_int();
+					drives_[drive].head_unload_delay[head] -= cycles.as_integral();
 				}
 				timers_left--;
 				if(!timers_left) break;
@@ -163,7 +163,7 @@ void i8272::run_for(Cycles cycles) {
 	if(is_sleeping_) update_clocking_observer();
 }
 
-void i8272::set_register(int address, uint8_t value) {
+void i8272::write(int address, uint8_t value) {
 	// don't consider attempted sets to the status register
 	if(!address) return;
 
@@ -181,7 +181,7 @@ void i8272::set_register(int address, uint8_t value) {
 	}
 }
 
-uint8_t i8272::get_register(int address) {
+uint8_t i8272::read(int address) {
 	if(address) {
 		if(result_stack_.empty()) return 0xff;
 		uint8_t result = result_stack_.back();
@@ -292,7 +292,7 @@ void i8272::posit_event(int event_type) {
 			WAIT_FOR_EVENT(Event8272::CommandByte)
 			SetBusy();
 
-			static const std::size_t required_lengths[32] = {
+			static constexpr std::size_t required_lengths[32] = {
 				0,	0,	9,	3,	2,	9,	9,	2,
 				1,	9,	2,	0,	9,	6,	0,	3,
 				0,	9,	0,	0,	0,	0,	0,	0,
@@ -865,7 +865,7 @@ void i8272::posit_event(int event_type) {
 			SetDataRequest();
 			SetDataDirectionToProcessor();
 
-			// The actual stuff of unwinding result_stack_ is handled by ::get_register; wait
+			// The actual stuff of unwinding result_stack_ is handled by ::read; wait
 			// until the processor has read all result bytes.
 			WAIT_FOR_EVENT(Event8272::ResultEmpty);
 

Components/8272/i8272.hpp

@@ -33,13 +33,13 @@ class i8272: public Storage::Disk::MFMController {
 		void set_data_input(uint8_t value);
 		uint8_t get_data_output();
 
-		void set_register(int address, uint8_t value);
+		void write(int address, uint8_t value);
-		uint8_t get_register(int address);
+		uint8_t read(int address);
 
 		void set_dma_acknowledge(bool dack);
 		void set_terminal_count(bool tc);
 
-		ClockingHint::Preference preferred_clocking() override;
+		ClockingHint::Preference preferred_clocking() final;
 
 	protected:
 		virtual void select_drive(int number) = 0;
@@ -67,13 +67,13 @@ class i8272: public Storage::Disk::MFMController {
 			ResultEmpty = (1 << 5),
 			NoLongerReady = (1 << 6)
 		};
-		void posit_event(int type) override;
+		void posit_event(int type) final;
 		int interesting_event_mask_ = static_cast<int>(Event8272::CommandByte);
 		int resume_point_ = 0;
 		bool is_access_command_ = false;
 
 		// The counter used for ::Timer events.
-		int delay_time_ = 0;
+		Cycles::IntType delay_time_ = 0;
 
 		// The connected drives.
 		struct Drive {
@@ -89,12 +89,12 @@ class i8272: public Storage::Disk::MFMController {
 			bool seek_failed = false;
 
 			// Seeking: transient state.
-			int step_rate_counter = 0;
+			Cycles::IntType step_rate_counter = 0;
 			int steps_taken = 0;
 			int target_head_position = 0;	// either an actual number, or -1 to indicate to step until track zero
 
 			// Head state.
-			int head_unload_delay[2] = {0, 0};
+			Cycles::IntType head_unload_delay[2] = {0, 0};
 			bool head_is_loaded[2] = {false, false};
 
 		} drives_[4];

Components/9918/9918.cpp

@@ -17,16 +17,16 @@ using namespace TI::TMS;
 
 namespace {
 
-const uint8_t StatusInterrupt = 0x80;
+constexpr uint8_t StatusInterrupt = 0x80;
-const uint8_t StatusSpriteOverflow = 0x40;
+constexpr uint8_t StatusSpriteOverflow = 0x40;
 
-const int StatusSpriteCollisionShift = 5;
+constexpr int StatusSpriteCollisionShift = 5;
-const uint8_t StatusSpriteCollision = 0x20;
+constexpr uint8_t StatusSpriteCollision = 0x20;
 
 // 342 internal cycles are 228/227.5ths of a line, so 341.25 cycles should be a whole
 // line. Therefore multiply everything by four, but set line length to 1365 rather than 342*4 = 1368.
-const unsigned int CRTCyclesPerLine = 1365;
+constexpr unsigned int CRTCyclesPerLine = 1365;
-const unsigned int CRTCyclesDivider = 4;
+constexpr unsigned int CRTCyclesDivider = 4;
 
 struct ReverseTable {
 	std::uint8_t map[256];
@@ -117,6 +117,14 @@ void TMS9918::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
 	crt_.set_scan_target(scan_target);
 }
 
+Outputs::Display::ScanStatus TMS9918::get_scaled_scan_status() const {
+	// The input was scaled by 3/4 to convert half cycles to internal ticks,
+	// so undo that and also allow for: (i) the multiply by 4 that it takes
+	// to reach the CRT; and (ii) the fact that the half-cycles value was scaled,
+	// and this should really reply in whole cycles.
+	return crt_.get_scaled_scan_status() * (4.0f / (3.0f * 8.0f));
+}
+
 void TMS9918::set_display_type(Outputs::Display::DisplayType display_type) {
 	crt_.set_display_type(display_type);
 }
@@ -166,7 +174,7 @@ void TMS9918::run_for(const HalfCycles cycles) {
 	// Convert 456 clocked half cycles per line to 342 internal cycles per line;
 	// the internal clock is 1.5 times the nominal 3.579545 Mhz that I've advertised
 	// for this part. So multiply by three quarters.
-	int int_cycles = (cycles.as_int() * 3) + cycles_error_;
+	int int_cycles = int(cycles.as_integral() * 3) + cycles_error_;
 	cycles_error_ = int_cycles & 3;
 	int_cycles >>= 2;
 	if(!int_cycles) return;
@@ -352,8 +360,7 @@ void TMS9918::run_for(const HalfCycles cycles) {
 				// Output video stream.
 				// --------------------
 
-#define intersect(left, right, code)	\
+#define intersect(left, right, code)	{	\
-	{	\
 		const int start = std::max(read_pointer_.column, left);	\
 		const int end = std::min(end_column, right);	\
 		if(end > start) {\
@@ -493,7 +500,7 @@ void Base::output_border(int cycles, uint32_t cram_dot) {
 	}
 }
 
-void TMS9918::set_register(int address, uint8_t value) {
+void TMS9918::write(int address, uint8_t value) {
 	// Writes to address 0 are writes to the video RAM. Store
 	// the value and return.
 	if(!(address & 1)) {
@@ -625,7 +632,7 @@ void TMS9918::set_register(int address, uint8_t value) {
 
 uint8_t TMS9918::get_current_line() {
 	// Determine the row to return.
-	static const int row_change_position = 63;	// This is the proper Master System value; substitute if any other VDPs turn out to have this functionality.
+	constexpr int row_change_position = 63;	// This is the proper Master System value; substitute if any other VDPs turn out to have this functionality.
 	int source_row =
 		(write_pointer_.column < row_change_position)
 			? (write_pointer_.row + mode_timing_.total_lines - 1)%mode_timing_.total_lines
@@ -671,7 +678,7 @@ void TMS9918::latch_horizontal_counter() {
 	latched_column_ = write_pointer_.column;
 }
 
-uint8_t TMS9918::get_register(int address) {
+uint8_t TMS9918::read(int address) {
 	write_phase_ = false;
 
 	// Reads from address 0 read video RAM, via the read-ahead buffer.
@@ -830,8 +837,8 @@ void Base::draw_tms_character(int start, int end) {
 		int sprite_collision = 0;
 		memset(&sprite_buffer[start], 0, size_t(end - start)*sizeof(sprite_buffer[0]));
 
-		static const uint32_t sprite_colour_selection_masks[2] = {0x00000000, 0xffffffff};
+		constexpr uint32_t sprite_colour_selection_masks[2] = {0x00000000, 0xffffffff};
-		static const int colour_masks[16] = {0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
+		constexpr int colour_masks[16] = {0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
 
 		// Draw all sprites into the sprite buffer.
 		const int shifter_target = sprites_16x16_ ? 32 : 16;

Components/9918/9918.hpp

@@ -44,6 +44,9 @@ class TMS9918: public Base {
 		/*! Sets the scan target this TMS will post content to. */
 		void set_scan_target(Outputs::Display::ScanTarget *);
 
+		/// Gets the current scan status.
+		Outputs::Display::ScanStatus get_scaled_scan_status() const;
+
 		/*! Sets the type of display the CRT will request. */
 		void set_display_type(Outputs::Display::DisplayType);
 
@@ -54,10 +57,10 @@ class TMS9918: public Base {
 		void run_for(const HalfCycles cycles);
 
 		/*! Sets a register value. */
-		void set_register(int address, uint8_t value);
+		void write(int address, uint8_t value);
 
 		/*! Gets a register value. */
-		uint8_t get_register(int address);
+		uint8_t read(int address);
 
 		/*! Gets the current scan line; provided by the Master System only. */
 		uint8_t get_current_line();
@@ -69,8 +72,8 @@ class TMS9918: public Base {
 		void latch_horizontal_counter();
 
 		/*!
-			Returns the amount of time until get_interrupt_line would next return true if
+			Returns the amount of time until @c get_interrupt_line would next return true if
-			there are no interceding calls to set_register or get_register.
+			there are no interceding calls to @c write or to @c read.
 
 			If get_interrupt_line is true now, returns zero. If get_interrupt_line would
 			never return true, returns -1.

Components/9918/Implementation/9918Base.hpp

@@ -100,7 +100,7 @@ class Base {
 			// (though, in practice, it won't happen until the next
 			// external slot after this number of cycles after the
 			// device has requested the read or write).
-			return 7;
+			return 6;
 		}
 
 		// Holds the main status register.

Components/AY38910/AY38910.cpp

@@ -6,51 +6,66 @@
 //  Copyright 2016 Thomas Harte. All rights reserved.
 //
 
+#include <cmath>
+
 #include "AY38910.hpp"
 
-#include <cmath>
+//namespace GI {
+//namespace AY38910 {
 
 using namespace GI::AY38910;
 
-AY38910::AY38910(Concurrency::DeferringAsyncTaskQueue &task_queue) : task_queue_(task_queue) {
+template <bool is_stereo>
-	// set up envelope lookup tables
+AY38910<is_stereo>::AY38910(Personality personality, Concurrency::DeferringAsyncTaskQueue &task_queue) : task_queue_(task_queue) {
+	// Don't use the low bit of the envelope position if this is an AY.
+	envelope_position_mask_ |= personality == Personality::AY38910;
+
+	// Set up envelope lookup tables.
 	for(int c = 0; c < 16; c++) {
-		for(int p = 0; p < 32; p++) {
+		for(int p = 0; p < 64; p++) {
 			switch(c) {
 				case 0: case 1: case 2: case 3: case 9:
-					envelope_shapes_[c][p] = (p < 16) ? (p^0xf) : 0;
+					/* Envelope: \____ */
-					envelope_overflow_masks_[c] = 0x1f;
+					envelope_shapes_[c][p] = (p < 32) ? (p^0x1f) : 0;
+					envelope_overflow_masks_[c] = 0x3f;
 				break;
 				case 4: case 5: case 6: case 7: case 15:
-					envelope_shapes_[c][p] = (p < 16) ? p : 0;
+					/* Envelope: /____ */
-					envelope_overflow_masks_[c] = 0x1f;
+					envelope_shapes_[c][p] = (p < 32) ? p : 0;
+					envelope_overflow_masks_[c] = 0x3f;
 				break;
 
 				case 8:
-					envelope_shapes_[c][p] = (p & 0xf) ^ 0xf;
+					/* Envelope: \\\\\\\\ */
+					envelope_shapes_[c][p] = (p & 0x1f) ^ 0x1f;
 					envelope_overflow_masks_[c] = 0x00;
 				break;
 				case 12:
-					envelope_shapes_[c][p] = (p & 0xf);
+					/* Envelope: //////// */
+					envelope_shapes_[c][p] = (p & 0x1f);
 					envelope_overflow_masks_[c] = 0x00;
 				break;
 
 				case 10:
-					envelope_shapes_[c][p] = (p & 0xf) ^ ((p < 16) ? 0xf : 0x0);
+					/* Envelope: \/\/\/\/ */
+					envelope_shapes_[c][p] = (p & 0x1f) ^ ((p < 32) ? 0x1f : 0x0);
 					envelope_overflow_masks_[c] = 0x00;
 				break;
 				case 14:
-					envelope_shapes_[c][p] = (p & 0xf) ^ ((p < 16) ? 0x0 : 0xf);
+					/* Envelope: /\/\/\/\ */
+					envelope_shapes_[c][p] = (p & 0x1f) ^ ((p < 32) ? 0x0 : 0x1f);
 					envelope_overflow_masks_[c] = 0x00;
 				break;
 
 				case 11:
-					envelope_shapes_[c][p] = (p < 16) ? (p^0xf) : 0xf;
+					/* Envelope: \------	(if - is high) */
-					envelope_overflow_masks_[c] = 0x1f;
+					envelope_shapes_[c][p] = (p < 32) ? (p^0x1f) : 0x1f;
+					envelope_overflow_masks_[c] = 0x3f;
 				break;
 				case 13:
-					envelope_shapes_[c][p] = (p < 16) ? p : 0xf;
+					/* Envelope: /------- */
-					envelope_overflow_masks_[c] = 0x1f;
+					envelope_shapes_[c][p] = (p < 32) ? p : 0x1f;
+					envelope_overflow_masks_[c] = 0x3f;
 				break;
 			}
 		}
@@ -59,21 +74,50 @@ AY38910::AY38910(Concurrency::DeferringAsyncTaskQueue &task_queue) : task_queue_
 	set_sample_volume_range(0);
 }
 
-void AY38910::set_sample_volume_range(std::int16_t range) {
+template <bool is_stereo> void AY38910<is_stereo>::set_sample_volume_range(std::int16_t range) {
-	// set up volume lookup table
+	// Set up volume lookup table; the function below is based on a combination of the graph
-	const float max_volume = static_cast<float>(range) / 3.0f;	// As there are three channels.
+	// from the YM's datasheet, showing a clear power curve, and fitting that to observed
-	const float root_two = sqrtf(2.0f);
+	// values reported elsewhere.
-	for(int v = 0; v < 16; v++) {
+	const float max_volume = float(range) / 3.0f;	// As there are three channels.
-		volumes_[v] = static_cast<int>(max_volume / powf(root_two, static_cast<float>(v ^ 0xf)));
+	constexpr float root_two = 1.414213562373095f;
+	for(int v = 0; v < 32; v++) {
+		volumes_[v] = int(max_volume / powf(root_two, float(v ^ 0x1f) / 3.18f));
 	}
-	volumes_[0] = 0;
+
+	// Tie level 0 to silence.
+	for(int v = 31; v >= 0; --v) {
+		volumes_[v] -= volumes_[0];
+	}
+
 	evaluate_output_volume();
 }
 
-void AY38910::get_samples(std::size_t number_of_samples, int16_t *target) {
+template <bool is_stereo> void AY38910<is_stereo>::set_output_mixing(float a_left, float b_left, float c_left, float a_right, float b_right, float c_right) {
+	a_left_ = uint8_t(a_left * 255.0f);
+	b_left_ = uint8_t(b_left * 255.0f);
+	c_left_ = uint8_t(c_left * 255.0f);
+	a_right_ = uint8_t(a_right * 255.0f);
+	b_right_ = uint8_t(b_right * 255.0f);
+	c_right_ = uint8_t(c_right * 255.0f);
+}
+
+template <bool is_stereo> void AY38910<is_stereo>::get_samples(std::size_t number_of_samples, int16_t *target) {
+	// Note on structure below: the real AY has a built-in divider of 8
+	// prior to applying its tone and noise dividers. But the YM fills the
+	// same total periods for noise and tone with double-precision envelopes.
+	// Therefore this class implements a divider of 4 and doubles the tone
+	// and noise periods. The envelope ticks along at the divide-by-four rate,
+	// but if this is an AY rather than a YM then its lowest bit is forced to 1,
+	// matching the YM datasheet's depiction of envelope level 31 as equal to
+	// programmatic volume 15, envelope level 29 as equal to programmatic 14, etc.
+
 	std::size_t c = 0;
-	while((master_divider_&7) && c < number_of_samples) {
+	while((master_divider_&3) && c < number_of_samples) {
-		target[c] = output_volume_;
+		if constexpr (is_stereo) {
+			reinterpret_cast<uint32_t *>(target)[c] = output_volume_;
+		} else {
+			target[c] = int16_t(output_volume_);
+		}
 		master_divider_++;
 		c++;
 	}
@@ -83,49 +127,53 @@ void AY38910::get_samples(std::size_t number_of_samples, int16_t *target) {
 	if(tone_counters_[c]) tone_counters_[c]--;\
 	else {\
 		tone_outputs_[c] ^= 1;\
-		tone_counters_[c] = tone_periods_[c];\
+		tone_counters_[c] = tone_periods_[c] << 1;\
 	}
 
-		// update the tone channels
+		// Update the tone channels.
 		step_channel(0);
 		step_channel(1);
 		step_channel(2);
 
 #undef step_channel
 
-		// ... the noise generator. This recomputes the new bit repeatedly but harmlessly, only shifting
+		// Update the noise generator. This recomputes the new bit repeatedly but harmlessly, only shifting
 		// it into the official 17 upon divider underflow.
 		if(noise_counter_) noise_counter_--;
 		else {
-			noise_counter_ = noise_period_;
+			noise_counter_ = noise_period_ << 1;	// To cover the double resolution of envelopes.
 			noise_output_ ^= noise_shift_register_&1;
 			noise_shift_register_ |= ((noise_shift_register_ ^ (noise_shift_register_ >> 3))&1) << 17;
 			noise_shift_register_ >>= 1;
 		}
 
-		// ... and the envelope generator. Table based for pattern lookup, with a 'refill' step: a way of
+		// Update the envelope generator. Table based for pattern lookup, with a 'refill' step: a way of
-		// implementing non-repeating patterns by locking them to table position 0x1f.
+		// implementing non-repeating patterns by locking them to the final table position.
 		if(envelope_divider_) envelope_divider_--;
 		else {
 			envelope_divider_ = envelope_period_;
 			envelope_position_ ++;
-			if(envelope_position_ == 32) envelope_position_ = envelope_overflow_masks_[output_registers_[13]];
+			if(envelope_position_ == 64) envelope_position_ = envelope_overflow_masks_[output_registers_[13]];
 		}
 
 		evaluate_output_volume();
 
-		for(int ic = 0; ic < 8 && c < number_of_samples; ic++) {
+		for(int ic = 0; ic < 4 && c < number_of_samples; ic++) {
-			target[c] = output_volume_;
+			if constexpr (is_stereo) {
+				reinterpret_cast<uint32_t *>(target)[c] = output_volume_;
+			} else {
+				target[c] = int16_t(output_volume_);
+			}
 			c++;
 			master_divider_++;
 		}
 	}
 
-	master_divider_ &= 7;
+	master_divider_ &= 3;
 }
 
-void AY38910::evaluate_output_volume() {
+template <bool is_stereo> void AY38910<is_stereo>::evaluate_output_volume() {
-	int envelope_volume = envelope_shapes_[output_registers_[13]][envelope_position_];
+	int envelope_volume = envelope_shapes_[output_registers_[13]][envelope_position_ | envelope_position_mask_];
 
 	// The output level for a channel is:
 	//	1 if neither tone nor noise is enabled;
@@ -142,9 +190,20 @@ void AY38910::evaluate_output_volume() {
 	};
 #undef level
 
-		// Channel volume is a simple selection: if the bit at 0x10 is set, use the envelope volume; otherwise use the lower four bits
+	// This remapping table seeks to map 'channel volumes', i.e. the levels produced from the
+	// 16-step progammatic volumes set per channel to 'envelope volumes', i.e. the 32-step
+	// volumes that are produced by the envelope generators (on a YM at least). My reading of
+	// the data sheet is that '0' is still off, but 15 should be as loud as peak envelope. So
+	// I've thrown in the discontinuity at the low end, where it'll be very quiet.
+	const int channel_volumes[] = {
+		0, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31
+	};
+	static_assert(sizeof(channel_volumes) == 16*sizeof(int));
+
+		// Channel volume is a simple selection: if the bit at 0x10 is set, use the envelope volume; otherwise use the lower four bits,
+		// mapped to the range 1–31 in case this is a YM.
 #define channel_volume(c)	\
-	((output_registers_[c] >> 4)&1) * envelope_volume + (((output_registers_[c] >> 4)&1)^1) * (output_registers_[c]&0xf)
+	((output_registers_[c] >> 4)&1) * envelope_volume + (((output_registers_[c] >> 4)&1)^1) * channel_volumes[output_registers_[c]&0xf]
 
 	const int volumes[3] = {
 		channel_volume(8),
@@ -153,34 +212,47 @@ void AY38910::evaluate_output_volume() {
 	};
 #undef channel_volume
 
-	// Mix additively.
+	// Mix additively, weighting if in stereo.
-	output_volume_ = static_cast<int16_t>(
+	if constexpr (is_stereo) {
+		int16_t *const output_volumes = reinterpret_cast<int16_t *>(&output_volume_);
+		output_volumes[0] = int16_t((
+			volumes_[volumes[0]] * channel_levels[0] * a_left_ +
+			volumes_[volumes[1]] * channel_levels[1] * b_left_ +
+			volumes_[volumes[2]] * channel_levels[2] * c_left_
+		) >> 8);
+		output_volumes[1] = int16_t((
+			volumes_[volumes[0]] * channel_levels[0] * a_right_ +
+			volumes_[volumes[1]] * channel_levels[1] * b_right_ +
+			volumes_[volumes[2]] * channel_levels[2] * c_right_
+		) >> 8);
+	} else {
+		output_volume_ = uint32_t(
 			volumes_[volumes[0]] * channel_levels[0] +
 			volumes_[volumes[1]] * channel_levels[1] +
 			volumes_[volumes[2]] * channel_levels[2]
 		);
 	}
+}
 
-bool AY38910::is_zero_level() {
+template <bool is_stereo> bool AY38910<is_stereo>::is_zero_level() {
 	// Confirm that the AY is trivially at the zero level if all three volume controls are set to fixed zero.
 	return output_registers_[0x8] == 0 && output_registers_[0x9] == 0 && output_registers_[0xa] == 0;
 }
 
 // MARK: - Register manipulation
 
-void AY38910::select_register(uint8_t r) {
+template <bool is_stereo> void AY38910<is_stereo>::select_register(uint8_t r) {
 	selected_register_ = r;
 }
 
-void AY38910::set_register_value(uint8_t value) {
+template <bool is_stereo> void AY38910<is_stereo>::set_register_value(uint8_t value) {
 	// There are only 16 registers.
 	if(selected_register_ > 15) return;
 
 	// If this is a register that affects audio output, enqueue a mutation onto the
 	// audio generation thread.
 	if(selected_register_ < 14) {
-		const int selected_register = selected_register_;
+		task_queue_.defer([this, selected_register = selected_register_, value] () {
-		task_queue_.defer([=] () {
 			// Perform any register-specific mutation to output generation.
 			uint8_t masked_value = value;
 			switch(selected_register) {
@@ -189,7 +261,7 @@ void AY38910::set_register_value(uint8_t value) {
 					int channel = selected_register >> 1;
 
 					if(selected_register & 1)
-						tone_periods_[channel] = (tone_periods_[channel] & 0xff) | static_cast<uint16_t>((value&0xf) << 8);
+						tone_periods_[channel] = (tone_periods_[channel] & 0xff) | uint16_t((value&0xf) << 8);
 					else
 						tone_periods_[channel] = (tone_periods_[channel] & ~0xff) | value;
 				}
@@ -204,7 +276,7 @@ void AY38910::set_register_value(uint8_t value) {
 				break;
 
 				case 12:
-					envelope_period_ = (envelope_period_ & 0xff) | static_cast<int>(value << 8);
+					envelope_period_ = (envelope_period_ & 0xff) | int(value << 8);
 				break;
 
 				case 13:
@@ -242,7 +314,7 @@ void AY38910::set_register_value(uint8_t value) {
 	if(update_port_a) set_port_output(false);
 }
 
-uint8_t AY38910::get_register_value() {
+template <bool is_stereo> uint8_t AY38910<is_stereo>::get_register_value() {
 	// This table ensures that bits that aren't defined within the AY are returned as 0s
 	// when read, conforming to CPC-sourced unit tests.
 	const uint8_t register_masks[16] = {
@@ -256,24 +328,24 @@ uint8_t AY38910::get_register_value() {
 
 // MARK: - Port querying
 
-uint8_t AY38910::get_port_output(bool port_b) {
+template <bool is_stereo> uint8_t AY38910<is_stereo>::get_port_output(bool port_b) {
 	return registers_[port_b ? 15 : 14];
 }
 
 // MARK: - Bus handling
 
-void AY38910::set_port_handler(PortHandler *handler) {
+template <bool is_stereo> void AY38910<is_stereo>::set_port_handler(PortHandler *handler) {
 	port_handler_ = handler;
 	set_port_output(true);
 	set_port_output(false);
 }
 
-void AY38910::set_data_input(uint8_t r) {
+template <bool is_stereo> void AY38910<is_stereo>::set_data_input(uint8_t r) {
 	data_input_ = r;
 	update_bus();
 }
 
-void AY38910::set_port_output(bool port_b) {
+template <bool is_stereo> void AY38910<is_stereo>::set_port_output(bool port_b) {
 	// Per the data sheet: "each [IO] pin is provided with an on-chip pull-up resistor,
 	// so that when in the "input" mode, all pins will read normally high". Therefore,
 	// report programmer selection of input mode as creating an output of 0xff.
@@ -283,7 +355,7 @@ void AY38910::set_port_output(bool port_b) {
 	}
 }
 
-uint8_t AY38910::get_data_output() {
+template <bool is_stereo> uint8_t AY38910<is_stereo>::get_data_output() {
 	if(control_state_ == Read && selected_register_ >= 14 && selected_register_ < 16) {
 		// Per http://cpctech.cpc-live.com/docs/psgnotes.htm if a port is defined as output then the
 		// value returned to the CPU when reading it is the and of the output value and any input.
@@ -299,22 +371,22 @@ uint8_t AY38910::get_data_output() {
 	return data_output_;
 }
 
-void AY38910::set_control_lines(ControlLines control_lines) {
+template <bool is_stereo> void AY38910<is_stereo>::set_control_lines(ControlLines control_lines) {
-	switch(static_cast<int>(control_lines)) {
+	switch(int(control_lines)) {
 		default:					control_state_ = Inactive;		break;
 
-		case static_cast<int>(BDIR | BC2 | BC1):
+		case int(BDIR | BC2 | BC1):
 		case BDIR:
 		case BC1:					control_state_ = LatchAddress;	break;
 
-		case static_cast<int>(BC2 | BC1):		control_state_ = Read;			break;
+		case int(BC2 | BC1):		control_state_ = Read;			break;
-		case static_cast<int>(BDIR | BC2):		control_state_ = Write;			break;
+		case int(BDIR | BC2):		control_state_ = Write;			break;
 	}
 
 	update_bus();
 }
 
-void AY38910::update_bus() {
+template <bool is_stereo> void AY38910<is_stereo>::update_bus() {
 	// Assume no output, unless this turns out to be a read.
 	data_output_ = 0xff;
 	switch(control_state_) {
@@ -324,3 +396,7 @@ void AY38910::update_bus() {
 		case Read:			data_output_ = get_register_value();	break;
 	}
 }
+
+// Ensure both mono and stereo versions of the AY are built.
+template class GI::AY38910::AY38910<true>;
+template class GI::AY38910::AY38910<false>;

Components/AY38910/AY38910.hpp

@@ -35,9 +35,10 @@ class PortHandler {
 		}
 
 		/*!
-			Requests the current input on an AY port.
+			Sets the current output on an AY port.
 
-			@param port_b @c true if the input being queried is Port B. @c false if it is Port A.
+			@param port_b @c true if the output being posted is Port B. @c false if it is Port A.
+			@param value the value now being output.
 		*/
 		virtual void set_port_output(bool port_b, uint8_t value) {}
 };
@@ -51,15 +52,24 @@ enum ControlLines {
 	BDIR	= (1 << 2)
 };
 
+enum class Personality {
+	/// Provides 16 volume levels to envelopes.
+	AY38910,
+	/// Provides 32 volume levels to envelopes.
+	YM2149F
+};
+
 /*!
 	Provides emulation of an AY-3-8910 / YM2149, which is a three-channel sound chip with a
 	noise generator and a volume envelope generator, which also provides two bidirectional
 	interface ports.
+
+	This AY has an attached mono or stereo mixer.
 */
-class AY38910: public ::Outputs::Speaker::SampleSource {
+template <bool is_stereo> class AY38910: public ::Outputs::Speaker::SampleSource {
 	public:
 		/// Creates a new AY38910.
-		AY38910(Concurrency::DeferringAsyncTaskQueue &task_queue);
+		AY38910(Personality, Concurrency::DeferringAsyncTaskQueue &);
 
 		/// Sets the value the AY would read from its data lines if it were not outputting.
 		void set_data_input(uint8_t r);
@@ -83,10 +93,23 @@ class AY38910: public ::Outputs::Speaker::SampleSource {
 		*/
 		void set_port_handler(PortHandler *);
 
+		/*!
+			Enables or disables stereo output; if stereo output is enabled then also sets the weight of each of the AY's
+			channels in each of the output channels.
+
+			If a_left_ = b_left = c_left = a_right = b_right = c_right = 1.0 then you'll get output that's effectively mono.
+
+			a_left = 0.0, a_right = 1.0 will make A full volume on the right output, and silent on the left.
+
+			a_left = 0.5, a_right = 0.5 will make A half volume on both outputs.
+		*/
+		void set_output_mixing(float a_left, float b_left, float c_left, float a_right = 1.0, float b_right = 1.0, float c_right = 1.0);
+
 		// to satisfy ::Outputs::Speaker (included via ::Outputs::Filter.
 		void get_samples(std::size_t number_of_samples, int16_t *target);
 		bool is_zero_level();
 		void set_sample_volume_range(std::int16_t range);
+		static constexpr bool get_is_stereo() { return is_stereo; }
 
 	private:
 		Concurrency::DeferringAsyncTaskQueue &task_queue_;
@@ -108,11 +131,11 @@ class AY38910: public ::Outputs::Speaker::SampleSource {
 
 		int envelope_period_ = 0;
 		int envelope_divider_ = 0;
-		int envelope_position_ = 0;
+		int envelope_position_ = 0, envelope_position_mask_ = 0;
-		int envelope_shapes_[16][32];
+		int envelope_shapes_[16][64];
 		int envelope_overflow_masks_[16];
 
-		int volumes_[16];
+		int volumes_[32];
 
 		enum ControlState {
 			Inactive,
@@ -127,14 +150,21 @@ class AY38910: public ::Outputs::Speaker::SampleSource {
 
 		uint8_t data_input_, data_output_;
 
-		int16_t output_volume_;
+		uint32_t output_volume_;
-		void evaluate_output_volume();
 
 		void update_bus();
 		PortHandler *port_handler_ = nullptr;
 		void set_port_output(bool port_b);
+
+		void evaluate_output_volume();
+
+		// Output mixing control.
+		uint8_t a_left_ = 255, a_right_ = 255;
+		uint8_t b_left_ = 255, b_right_ = 255;
+		uint8_t c_left_ = 255, c_right_ = 255;
 };
 
+
 }
 }
 

Components/AudioToggle/AudioToggle.cpp

@@ -28,7 +28,7 @@ void Toggle::skip_samples(const std::size_t number_of_samples) {}
 void Toggle::set_output(bool enabled) {
 	if(is_enabled_ == enabled) return;
 	is_enabled_ = enabled;
-	audio_queue_.defer([=] {
+	audio_queue_.defer([this, enabled] {
 		level_ = enabled ? volume_ : 0;
 	});
 }

Components/AudioToggle/AudioToggle.hpp

@@ -24,6 +24,7 @@ class Toggle: public Outputs::Speaker::SampleSource {
 		void get_samples(std::size_t number_of_samples, std::int16_t *target);
 		void set_sample_volume_range(std::int16_t range);
 		void skip_samples(const std::size_t number_of_samples);
+		static constexpr bool get_is_stereo() { return false; }
 
 		void set_output(bool enabled);
 		bool get_output();

Components/DiskII/DiskII.cpp

@@ -78,7 +78,7 @@ void DiskII::select_drive(int drive) {
 void DiskII::run_for(const Cycles cycles) {
 	if(preferred_clocking() == ClockingHint::Preference::None) return;
 
-	int integer_cycles = cycles.as_int();
+	auto integer_cycles = cycles.as_integral();
 	while(integer_cycles--) {
 		const int address = (state_ & 0xf0) | inputs_ | ((shift_register_&0x80) >> 6);
 		if(flux_duration_) {
@@ -124,7 +124,7 @@ void DiskII::run_for(const Cycles cycles) {
 	// motor switch being flipped and the drive motor actually switching off.
 	// This models that, accepting overrun as a risk.
 	if(motor_off_time_ >= 0) {
-		motor_off_time_ -= cycles.as_int();
+		motor_off_time_ -= cycles.as_integral();
 		if(motor_off_time_ < 0) {
 			set_control(Control::Motor, false);
 		}
@@ -266,7 +266,7 @@ int DiskII::read_address(int address) {
 		break;
 		case 0xf:
 			if(!(inputs_ & input_mode))
-				drives_[active_drive_].begin_writing(Storage::Time(1, clock_rate_), false);
+				drives_[active_drive_].begin_writing(Storage::Time(1, int(clock_rate_)), false);
 			inputs_ |= input_mode;
 		break;
 	}

Components/DiskII/DiskII.hpp

@@ -48,7 +48,7 @@ class DiskII:
 			The value returned by @c read_address if accessing that address
 			didn't cause the disk II to place anything onto the bus.
 		*/
-		const int DidNotLoad = -1;
+		static constexpr int DidNotLoad = -1;
 
 		/// Advances the controller by @c cycles.
 		void run_for(const Cycles cycles);
@@ -76,7 +76,7 @@ class DiskII:
 		void set_disk(const std::shared_ptr<Storage::Disk::Disk> &disk, int drive);
 
 		// As per Sleeper.
-		ClockingHint::Preference preferred_clocking() override;
+		ClockingHint::Preference preferred_clocking() final;
 
 		// The Disk II functions as a potential target for @c Activity::Sources.
 		void set_activity_observer(Activity::Observer *observer);
@@ -98,10 +98,10 @@ class DiskII:
 		void select_drive(int drive);
 
 		uint8_t trigger_address(int address, uint8_t value);
-		void process_event(const Storage::Disk::Drive::Event &event) override;
+		void process_event(const Storage::Disk::Drive::Event &event) final;
-		void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference preference) override;
+		void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference preference) final;
 
-		const int clock_rate_ = 0;
+		const Cycles::IntType clock_rate_ = 0;
 
 		uint8_t state_ = 0;
 		uint8_t inputs_ = 0;
@@ -109,7 +109,7 @@ class DiskII:
 
 		int stepper_mask_ = 0;
 		int stepper_position_ = 0;
-		int motor_off_time_ = -1;
+		Cycles::IntType motor_off_time_ = -1;
 
 		bool is_write_protected();
 		std::array<uint8_t, 256> state_machine_;

Components/DiskII/IWM.cpp

@@ -13,15 +13,15 @@
 using namespace Apple;
 
 namespace  {
-	const int CA0		= 1 << 0;
+	constexpr int CA0		= 1 << 0;
-	const int CA1		= 1 << 1;
+	constexpr int CA1		= 1 << 1;
-	const int CA2		= 1 << 2;
+	constexpr int CA2		= 1 << 2;
-	const int LSTRB		= 1 << 3;
+	constexpr int LSTRB		= 1 << 3;
-	const int ENABLE	= 1 << 4;
+	constexpr int ENABLE	= 1 << 4;
-	const int DRIVESEL	= 1 << 5;	/* This means drive select, like on the original Disk II. */
+	constexpr int DRIVESEL	= 1 << 5;	/* This means drive select, like on the original Disk II. */
-	const int Q6		= 1 << 6;
+	constexpr int Q6		= 1 << 6;
-	const int Q7		= 1 << 7;
+	constexpr int Q7		= 1 << 7;
-	const int SEL		= 1 << 8;	/* This is an additional input, not available on a Disk II, with a confusingly-similar name to SELECT but a distinct purpose. */
+	constexpr int SEL		= 1 << 8;	/* This is an additional input, not available on a Disk II, with a confusingly-similar name to SELECT but a distinct purpose. */
 }
 
 IWM::IWM(int clock_rate) :
@@ -233,25 +233,34 @@ void IWM::run_for(const Cycles cycles) {
 	}
 
 	// Activity otherwise depends on mode and motor state.
-	int integer_cycles = cycles.as_int();
+	auto integer_cycles = cycles.as_integral();
 	switch(shift_mode_) {
-		case ShiftMode::Reading:
+		case ShiftMode::Reading: {
+			// Per the IWM patent, column 7, around line 35 onwards: "The expected time
+			// is widened by approximately one-half an interval before and after the
+			// expected time since the data is not precisely spaced when read due to
+			// variations in drive speed and other external factors". The error_margin
+			// here implements the 'after' part of that contract.
+			const auto error_margin = Cycles(bit_length_.as_integral() >> 1);
+
 			if(drive_is_rotating_[active_drive_]) {
 				while(integer_cycles--) {
 					drives_[active_drive_]->run_for(Cycles(1));
 					++cycles_since_shift_;
-					if(cycles_since_shift_ == bit_length_ + Cycles(2)) {
+					if(cycles_since_shift_ == bit_length_ + error_margin) {
 						propose_shift(0);
 					}
 				}
 			} else {
-				while(cycles_since_shift_ + integer_cycles >= bit_length_ + Cycles(2)) {
+				while(cycles_since_shift_ + integer_cycles >= bit_length_ + error_margin) {
+					const auto run_length = bit_length_ + error_margin - cycles_since_shift_;
+					integer_cycles -= run_length.as_integral();
+					cycles_since_shift_ += run_length;
 					propose_shift(0);
-					integer_cycles -= bit_length_.as_int() + 2 - cycles_since_shift_.as_int();
 				}
 				cycles_since_shift_ += Cycles(integer_cycles);
 			}
-		break;
+		} break;
 
 		case ShiftMode::Writing:
 			if(drives_[active_drive_]->is_writing()) {
@@ -263,7 +272,7 @@ void IWM::run_for(const Cycles cycles) {
 					drives_[active_drive_]->write_bit(shift_register_ & 0x80);
 					shift_register_ <<= 1;
 
-					integer_cycles -= cycles_until_write.as_int();
+					integer_cycles -= cycles_until_write.as_integral();
 					cycles_since_shift_ = Cycles(0);
 
 					--output_bits_remaining_;
@@ -324,7 +333,7 @@ void IWM::select_shift_mode() {
 
 	// If writing mode just began, set the drive into write mode and cue up the first output byte.
 	if(drives_[active_drive_] && old_shift_mode != ShiftMode::Writing && shift_mode_ == ShiftMode::Writing) {
-		drives_[active_drive_]->begin_writing(Storage::Time(1, clock_rate_ / bit_length_.as_int()), false);
+		drives_[active_drive_]->begin_writing(Storage::Time(1, clock_rate_ / bit_length_.as_integral()), false);
 		shift_register_ = next_output_;
 		write_handshake_ |= 0x80 | 0x40;
 		output_bits_remaining_ = 8;
@@ -351,12 +360,28 @@ void IWM::propose_shift(uint8_t bit) {
 	// TODO: synchronous mode.
 
 //	LOG("Shifting input");
+
+	// See above for text from the IWM patent, column 7, around line 35 onwards.
+	// The error_margin here implements the 'before' part of that contract.
+	//
+	// Basic effective logic: if at least 1 is fozund in the bit_length_ cycles centred
+	// on the current expected bit delivery time as implied by cycles_since_shift_,
+	// shift in a 1 and start a new window wherever the first found 1 was.
+	//
+	// If no 1s are found, shift in a 0 and don't alter expectations as to window placement.
+	const auto error_margin = Cycles(bit_length_.as_integral() >> 1);
+	if(bit && cycles_since_shift_ < error_margin) return;
+
 	shift_register_ = uint8_t((shift_register_ << 1) | bit);
 	if(shift_register_ & 0x80) {
 		data_register_ = shift_register_;
 		shift_register_ = 0;
 	}
+
+	if(bit)
 		cycles_since_shift_ = Cycles(0);
+	else
+		cycles_since_shift_ -= bit_length_;
 }
 
 void IWM::set_drive(int slot, IWMDrive *drive) {
@@ -374,3 +399,8 @@ void IWM::set_component_prefers_clocking(ClockingHint::Source *component, Clocki
 		drive_is_rotating_[1] = is_rotating;
 	}
 }
+
+void IWM::set_activity_observer(Activity::Observer *observer) {
+	if(drives_[0]) drives_[0]->set_activity_observer(observer, "Internal Floppy", true);
+	if(drives_[1]) drives_[1]->set_activity_observer(observer, "External Floppy", true);
+}

Components/DiskII/IWM.hpp

@@ -9,8 +9,11 @@
 #ifndef IWM_hpp
 #define IWM_hpp
 
+#include "../../Activity/Observer.hpp"
+
 #include "../../ClockReceiver/ClockReceiver.hpp"
 #include "../../ClockReceiver/ClockingHintSource.hpp"
+
 #include "../../Storage/Disk/Drive.hpp"
 
 #include <cstdint>
@@ -67,9 +70,13 @@ class IWM:
 		/// Connects a drive to the IWM.
 		void set_drive(int slot, IWMDrive *drive);
 
+		/// Registers the currently-connected drives as @c Activity::Sources ;
+		/// the first will be declared 'Internal', the second 'External'.
+		void set_activity_observer(Activity::Observer *observer);
+
 	private:
 		// Storage::Disk::Drive::EventDelegate.
-		void process_event(const Storage::Disk::Drive::Event &event) override;
+		void process_event(const Storage::Disk::Drive::Event &event) final;
 
 		const int clock_rate_;
 
@@ -84,7 +91,7 @@ class IWM:
 		IWMDrive *drives_[2] = {nullptr, nullptr};
 		bool drive_is_rotating_[2] = {false, false};
 
-		void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference clocking) override;
+		void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference clocking) final;
 
 		Cycles cycles_until_disable_;
 		uint8_t write_handshake_ = 0x80;

Components/DiskII/MacintoshDoubleDensityDrive.cpp

@@ -71,7 +71,9 @@ void DoubleDensityDrive::set_rotation_speed(float revolutions_per_minute) {
 
 // MARK: - Control input/output.
 
-void DoubleDensityDrive::set_enabled(bool) {
+void DoubleDensityDrive::set_enabled(bool enabled) {
+	// Disabling a drive also stops its motor.
+	if(!enabled) set_motor_on(false);
 }
 
 void DoubleDensityDrive::set_control_lines(int lines) {

Components/DiskII/MacintoshDoubleDensityDrive.hpp

@@ -32,14 +32,14 @@ class DoubleDensityDrive: public IWMDrive {
 		*/
 		void set_rotation_speed(float revolutions_per_minute);
 
-		void set_enabled(bool) override;
-		void set_control_lines(int) override;
-		bool read() override;
-
 	private:
+		void set_enabled(bool) final;
+		void set_control_lines(int) final;
+		bool read() final;
+
 		// To receive the proper notifications from Storage::Disk::Drive.
-		void did_step(Storage::Disk::HeadPosition to_position) override;
+		void did_step(Storage::Disk::HeadPosition to_position) final;
-		void did_set_disk() override;
+		void did_set_disk() final;
 
 		const bool is_800k_;
 		bool has_new_disk_ = false;

Components/KonamiSCC/KonamiSCC.cpp

@@ -55,7 +55,7 @@ void SCC::write(uint16_t address, uint8_t value) {
 	address &= 0xff;
 	if(address < 0x80) ram_[address] = value;
 
-	task_queue_.defer([=] {
+	task_queue_.defer([this, address, value] {
 		// Check for a write into waveform memory.
 		if(address < 0x80) {
 			waves_[address >> 5].samples[address & 0x1f] = value;

Components/KonamiSCC/KonamiSCC.hpp

@@ -32,6 +32,7 @@ class SCC: public ::Outputs::Speaker::SampleSource {
 		/// As per ::SampleSource; provides audio output.
 		void get_samples(std::size_t number_of_samples, std::int16_t *target);
 		void set_sample_volume_range(std::int16_t range);
+		static constexpr bool get_is_stereo() { return false; }
 
 		/// Writes to the SCC.
 		void write(uint16_t address, uint8_t value);

Components/SN76489/SN76489.cpp

@@ -48,7 +48,7 @@ void SN76489::set_sample_volume_range(std::int16_t range) {
 	evaluate_output_volume();
 }
 
-void SN76489::set_register(uint8_t value) {
+void SN76489::write(uint8_t value) {
 	task_queue_.defer([value, this] () {
 		if(value & 0x80) {
 			active_register_ = value;

Components/SN76489/SN76489.hpp

@@ -26,12 +26,13 @@ class SN76489: public Outputs::Speaker::SampleSource {
 		SN76489(Personality personality, Concurrency::DeferringAsyncTaskQueue &task_queue, int additional_divider = 1);
 
 		/// Writes a new value to the SN76489.
-		void set_register(uint8_t value);
+		void write(uint8_t value);
 
 		// As per SampleSource.
 		void get_samples(std::size_t number_of_samples, std::int16_t *target);
 		bool is_zero_level();
 		void set_sample_volume_range(std::int16_t range);
+		static constexpr bool get_is_stereo() { return false; }
 
 	private:
 		int master_divider_ = 0;

Components/Serial/Line.cpp

@@ -0,0 +1,140 @@
+//
+//  SerialPort.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 12/10/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#include "Line.hpp"
+
+using namespace Serial;
+
+void Line::set_writer_clock_rate(HalfCycles clock_rate) {
+	clock_rate_ = clock_rate;
+}
+
+void Line::advance_writer(HalfCycles cycles) {
+	if(cycles == HalfCycles(0)) return;
+
+	const auto integral_cycles = cycles.as_integral();
+	remaining_delays_ = std::max(remaining_delays_ - integral_cycles, Cycles::IntType(0));
+	if(events_.empty()) {
+		write_cycles_since_delegate_call_ += integral_cycles;
+		if(transmission_extra_) {
+			transmission_extra_ -= integral_cycles;
+			if(transmission_extra_ <= 0) {
+				transmission_extra_ = 0;
+				update_delegate(level_);
+			}
+		}
+	} else {
+		while(!events_.empty()) {
+			if(events_.front().delay <= integral_cycles) {
+				cycles -= events_.front().delay;
+				write_cycles_since_delegate_call_ += events_.front().delay;
+				const auto old_level = level_;
+
+				auto iterator = events_.begin() + 1;
+				while(iterator != events_.end() && iterator->type != Event::Delay) {
+					level_ = iterator->type == Event::SetHigh;
+					++iterator;
+				}
+				events_.erase(events_.begin(), iterator);
+
+				if(old_level != level_) {
+					update_delegate(old_level);
+				}
+
+				// Book enough extra time for the read delegate to be posted
+				// the final bit if one is attached.
+				if(events_.empty()) {
+					transmission_extra_ = minimum_write_cycles_for_read_delegate_bit();
+				}
+			} else {
+				events_.front().delay -= integral_cycles;
+				write_cycles_since_delegate_call_ += integral_cycles;
+				break;
+			}
+		}
+	}
+}
+
+void Line::write(bool level) {
+	if(!events_.empty()) {
+		events_.emplace_back();
+		events_.back().type = level ? Event::SetHigh : Event::SetLow;
+	} else {
+		level_ = level;
+		transmission_extra_ = minimum_write_cycles_for_read_delegate_bit();
+	}
+}
+
+void Line::write(HalfCycles cycles, int count, int levels) {
+	remaining_delays_ += count * cycles.as_integral();
+
+	auto event = events_.size();
+	events_.resize(events_.size() + size_t(count)*2);
+	while(count--) {
+		events_[event].type = Event::Delay;
+		events_[event].delay = int(cycles.as_integral());
+		events_[event+1].type = (levels&1) ? Event::SetHigh : Event::SetLow;
+		levels >>= 1;
+		event += 2;
+	}
+}
+
+void Line::reset_writing() {
+	remaining_delays_ = 0;
+	events_.clear();
+}
+
+bool Line::read() {
+	return level_;
+}
+
+void Line::set_read_delegate(ReadDelegate *delegate, Storage::Time bit_length) {
+	read_delegate_ = delegate;
+	read_delegate_bit_length_ = bit_length;
+	read_delegate_bit_length_.simplify();
+	write_cycles_since_delegate_call_ = 0;
+}
+
+void Line::update_delegate(bool level) {
+	// Exit early if there's no delegate, or if the delegate is waiting for
+	// zero and this isn't zero.
+	if(!read_delegate_) return;
+
+	const int cycles_to_forward = write_cycles_since_delegate_call_;
+	write_cycles_since_delegate_call_ = 0;
+	if(level && read_delegate_phase_ == ReadDelegatePhase::WaitingForZero) return;
+
+	// Deal with a transition out of waiting-for-zero mode by seeding time left
+	// in bit at half a bit.
+	if(read_delegate_phase_ == ReadDelegatePhase::WaitingForZero) {
+		time_left_in_bit_ = read_delegate_bit_length_;
+		time_left_in_bit_.clock_rate <<= 1;
+		read_delegate_phase_ = ReadDelegatePhase::Serialising;
+	}
+
+	// Forward as many bits as occur.
+	Storage::Time time_left(cycles_to_forward, int(clock_rate_.as_integral()));
+	const int bit = level ? 1 : 0;
+	int bits = 0;
+	while(time_left >= time_left_in_bit_) {
+		++bits;
+		if(!read_delegate_->serial_line_did_produce_bit(this, bit)) {
+			read_delegate_phase_ = ReadDelegatePhase::WaitingForZero;
+			if(bit) return;
+		}
+
+		time_left -= time_left_in_bit_;
+		time_left_in_bit_ = read_delegate_bit_length_;
+	}
+	time_left_in_bit_ -= time_left;
+}
+
+Cycles::IntType Line::minimum_write_cycles_for_read_delegate_bit() {
+	if(!read_delegate_) return 0;
+	return 1 + (read_delegate_bit_length_ * static_cast<unsigned int>(clock_rate_.as_integral())).get<int>();
+}

Components/Serial/Line.hpp

@@ -0,0 +1,112 @@
+//
+//  SerialPort.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 12/10/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#ifndef SerialPort_hpp
+#define SerialPort_hpp
+
+#include <vector>
+#include "../../Storage/Storage.hpp"
+#include "../../ClockReceiver/ClockReceiver.hpp"
+#include "../../ClockReceiver/ForceInline.hpp"
+
+namespace Serial {
+
+/*!
+	@c Line connects a single reader and a single writer, allowing timestamped events to be
+	published and consumed, potentially with a clock conversion in between. It allows line
+	levels to be written and read in larger collections.
+
+	It is assumed that the owner of the reader and writer will ensure that the reader will never
+	get ahead of the writer. If the writer posts events behind the reader they will simply be
+	given instanteous effect.
+*/
+class Line {
+	public:
+		void set_writer_clock_rate(HalfCycles clock_rate);
+
+		/// Advances the read position by @c cycles relative to the writer's
+		/// clock rate.
+		void advance_writer(HalfCycles cycles);
+
+		/// Sets the line to @c level.
+		void write(bool level);
+
+		/// Enqueues @c count level changes, the first occurring immediately
+		/// after the final event currently posted and each subsequent event
+		/// occurring @c cycles after the previous. An additional gap of @c cycles
+		/// is scheduled after the final output. The levels to output are
+		/// taken from @c levels which is read from lsb to msb. @c cycles is
+		/// relative to the writer's clock rate.
+		void write(HalfCycles cycles, int count, int levels);
+
+		/// @returns the number of cycles until currently enqueued write data is exhausted.
+		forceinline HalfCycles write_data_time_remaining() const {
+			return HalfCycles(remaining_delays_);
+		}
+
+		/// @returns the number of cycles left until it is guaranteed that a passive reader
+		/// has received all currently-enqueued bits.
+		forceinline HalfCycles transmission_data_time_remaining() const {
+			return HalfCycles(remaining_delays_ + transmission_extra_);
+		}
+
+		/// Eliminates all future write states, leaving the output at whatever it is now.
+		void reset_writing();
+
+		/// @returns The instantaneous level of this line.
+		bool read();
+
+		struct ReadDelegate {
+			virtual bool serial_line_did_produce_bit(Line *line, int bit) = 0;
+		};
+		/*!
+			Sets a read delegate, which will receive samples of the output level every
+			@c bit_lengths of a second apart subject to a state machine:
+
+				* initially no bits will be delivered;
+				* when a zero level is first detected, the line will wait half a bit's length, then start
+				sampling at single-bit intervals, passing each bit to the delegate while it returns @c true;
+				* as soon as the delegate returns @c false, the line will return to the initial state.
+		*/
+		void set_read_delegate(ReadDelegate *delegate, Storage::Time bit_length);
+
+	private:
+		struct Event {
+			enum Type {
+				Delay, SetHigh, SetLow
+			} type;
+			int delay;
+		};
+		std::vector<Event> events_;
+		HalfCycles::IntType remaining_delays_ = 0;
+		HalfCycles::IntType transmission_extra_ = 0;
+		bool level_ = true;
+		HalfCycles clock_rate_ = 0;
+
+		ReadDelegate *read_delegate_ = nullptr;
+		Storage::Time read_delegate_bit_length_, time_left_in_bit_;
+		int write_cycles_since_delegate_call_ = 0;
+		enum class ReadDelegatePhase {
+			WaitingForZero,
+			Serialising
+		} read_delegate_phase_ = ReadDelegatePhase::WaitingForZero;
+
+		void update_delegate(bool level);
+		HalfCycles::IntType minimum_write_cycles_for_read_delegate_bit();
+};
+
+/*!
+	Defines an RS-232-esque srial port.
+*/
+class Port {
+	public:
+};
+
+}
+
+#endif /* SerialPort_hpp */

Concurrency/AsyncTaskQueue.cpp

@@ -18,7 +18,7 @@ AsyncTaskQueue::AsyncTaskQueue()
 #ifdef __APPLE__
 	serial_dispatch_queue_ = dispatch_queue_create("com.thomasharte.clocksignal.asyntaskqueue", DISPATCH_QUEUE_SERIAL);
 #else
-	thread_.reset(new std::thread([this]() {
+	thread_ = std::make_unique<std::thread>([this]() {
 		while(!should_destruct_) {
 			std::function<void(void)> next_function;
 
@@ -39,7 +39,7 @@ AsyncTaskQueue::AsyncTaskQueue()
 				processing_condition_.wait(lock);
 			}
 		}
-	}));
+	});
 #endif
 }
 
@@ -70,8 +70,8 @@ void AsyncTaskQueue::flush() {
 #ifdef __APPLE__
 	dispatch_sync(serial_dispatch_queue_, ^{});
 #else
-	std::shared_ptr<std::mutex> flush_mutex(new std::mutex);
+	auto flush_mutex = std::make_shared<std::mutex>();
-	std::shared_ptr<std::condition_variable> flush_condition(new std::condition_variable);
+	auto flush_condition = std::make_shared<std::condition_variable>();
 	std::unique_lock<std::mutex> lock(*flush_mutex);
 	enqueue([=] () {
 		std::unique_lock<std::mutex> inner_lock(*flush_mutex);
@@ -88,7 +88,7 @@ DeferringAsyncTaskQueue::~DeferringAsyncTaskQueue() {
 
 void DeferringAsyncTaskQueue::defer(std::function<void(void)> function) {
 	if(!deferred_tasks_) {
-		deferred_tasks_.reset(new std::list<std::function<void(void)>>);
+		deferred_tasks_ = std::make_shared<std::list<std::function<void(void)>>>();
 	}
 	deferred_tasks_->push_back(function);
 }

Concurrency/BestEffortUpdater.cpp

@@ -12,61 +12,89 @@
 
 using namespace Concurrency;
 
-BestEffortUpdater::BestEffortUpdater() {
+BestEffortUpdater::BestEffortUpdater() :
-	// ATOMIC_FLAG_INIT isn't necessarily safe to use, so establish default state by other means.
+	update_thread_([this]() {
-	update_is_ongoing_.clear();
+		this->update_loop();
-}
+	}) {}
 
 BestEffortUpdater::~BestEffortUpdater() {
-	// Don't allow further deconstruction until the task queue is stopped.
+	// Sever the delegate now, as soon as possible, then wait for any
+	// pending tasks to finish.
+	set_delegate(nullptr);
 	flush();
+
+	// Wind up the update thread.
+	should_quit_ = true;
+	update();
+	update_thread_.join();
 }
 
-void BestEffortUpdater::update() {
+void BestEffortUpdater::update(int flags) {
-	// Perform an update only if one is not currently ongoing.
+	// Bump the requested target time and set the update requested flag.
-	if(!update_is_ongoing_.test_and_set()) {
+	{
-		async_task_queue_.enqueue([this]() {
+		std::lock_guard<decltype(update_mutex_)> lock(update_mutex_);
-			// Get time now using the highest-resolution clock provided by the implementation, and determine
+		has_skipped_ = update_requested_;
-			// the duration since the last time this section was entered.
+		update_requested_ = true;
-			const std::chrono::time_point<std::chrono::high_resolution_clock> now = std::chrono::high_resolution_clock::now();
+		flags_ |= flags;
-			const auto elapsed = now - previous_time_point_;
+		target_time_ = std::chrono::high_resolution_clock::now().time_since_epoch().count();
-			previous_time_point_ = now;
+	}
+	update_condition_.notify_one();
+}
 
-			if(has_previous_time_point_) {
+void BestEffortUpdater::update_loop() {
-				// If the duration is valid, convert it to integer cycles, maintaining a rolling error and call the delegate
+ 	while(true) {
-				// if there is one. Proceed only if the number of cycles is positive, and cap it to the per-second maximum as
+		std::unique_lock<decltype(update_mutex_)> lock(update_mutex_);
-				// it's possible this is an adjustable clock so be ready to swallow unexpected adjustments.
+		is_updating_ = false;
-				const int64_t integer_duration = std::chrono::duration_cast<std::chrono::nanoseconds>(elapsed).count();
+
-				if(integer_duration > 0) {
+		// Wait to be signalled.
-					if(delegate_) {
+		update_condition_.wait(lock, [this]() -> bool {
+			return update_requested_;
+		});
+
+		// Possibly this signalling really means 'quit'.
+		if(should_quit_) return;
+
+		// Note update started, crib the target time.
+		auto target_time = target_time_;
+		update_requested_ = false;
+
+		// If this was actually the first update request, silently swallow it.
+		if(!has_previous_time_point_) {
+			has_previous_time_point_ = true;
+			previous_time_point_ = target_time;
+			continue;
+		}
+
+		// Release the lock on requesting new updates.
+		is_updating_ = true;
+		const int flags = flags_;
+		flags_ = 0;
+		lock.unlock();
+
+		// Invoke the delegate, if supplied, in order to run.
+		const int64_t integer_duration = std::max(target_time - previous_time_point_, int64_t(0));
+		const auto delegate = delegate_.load();
+		if(delegate) {
 			// Cap running at 1/5th of a second, to avoid doing a huge amount of work after any
 			// brief system interruption.
-						const double duration = std::min(static_cast<double>(integer_duration) / 1e9, 0.2);
+			const double duration = std::min(double(integer_duration) / 1e9, 0.2);
-						delegate_->update(this, duration, has_skipped_);
+			const double elapsed_duration = delegate->update(this, duration, has_skipped_, flags);
-					}
+
+			previous_time_point_ += int64_t(elapsed_duration * 1e9);
 			has_skipped_ = false;
 		}
-			} else {
-				has_previous_time_point_ = true;
-			}
-
-			// Allow furthers updates to occur.
-			update_is_ongoing_.clear();
-		});
-	} else {
-		async_task_queue_.enqueue([this]() {
-			has_skipped_ = true;
-		});
 	}
 }
 
 void BestEffortUpdater::flush() {
-	async_task_queue_.flush();
+	// Spin lock; this is allowed to be slow.
+	while(true) {
+		std::lock_guard<decltype(update_mutex_)> lock(update_mutex_);
+		if(!is_updating_) return;
+	}
 }
 
 void BestEffortUpdater::set_delegate(Delegate *const delegate) {
-	async_task_queue_.enqueue([this, delegate]() {
+	delegate_.store(delegate);
-		delegate_ = delegate;
-	});
 }
 

Concurrency/BestEffortUpdater.hpp

@@ -11,8 +11,10 @@
 
 #include <atomic>
 #include <chrono>
+#include <condition_variable>
+#include <mutex>
+#include <thread>
 
-#include "AsyncTaskQueue.hpp"
 #include "../ClockReceiver/TimeTypes.hpp"
 
 namespace Concurrency {
@@ -31,7 +33,13 @@ class BestEffortUpdater {
 
 		/// A delegate receives timing cues.
 		struct Delegate {
-			virtual void update(BestEffortUpdater *updater, Time::Seconds duration, bool did_skip_previous_update) = 0;
+			/*!
+				Instructs the delegate to run for at least @c duration, providing hints as to whether multiple updates were requested before the previous had completed
+				(as @c did_skip_previous_update) and providing the union of any flags supplied to @c update.
+
+				@returns The amount of time actually run for.
+			*/
+			virtual Time::Seconds update(BestEffortUpdater *updater, Time::Seconds duration, bool did_skip_previous_update, int flags) = 0;
 		};
 
 		/// Sets the current delegate.
@@ -41,20 +49,32 @@ class BestEffortUpdater {
 			If the delegate is not currently in the process of an `update` call, calls it now to catch up to the current time.
 			The call is asynchronous; this method will return immediately.
 		*/
-		void update();
+		void update(int flags = 0);
 
-		/// Blocks until any ongoing update is complete.
+		/// Blocks until any ongoing update is complete; may spin.
 		void flush();
 
 	private:
-		std::atomic_flag update_is_ongoing_;
+		std::atomic<bool> should_quit_;
-		AsyncTaskQueue async_task_queue_;
+		std::atomic<bool> is_updating_;
 
-		std::chrono::time_point<std::chrono::high_resolution_clock> previous_time_point_;
+		int64_t target_time_;
+		int flags_ = 0;
+		bool update_requested_;
+		std::mutex update_mutex_;
+		std::condition_variable update_condition_;
+
+		decltype(target_time_) previous_time_point_;
 		bool has_previous_time_point_ = false;
-		bool has_skipped_ = false;
+		std::atomic<bool> has_skipped_ = false;
 
-		Delegate *delegate_ = nullptr;
+		std::atomic<Delegate *>delegate_ = nullptr;
+
+		void update_loop();
+
+		// This is deliberately at the bottom, to ensure it constructs after the various
+		// mutexs, conditions, etc, that it'll depend upon.
+		std::thread update_thread_;
 };
 
 }

Configurable/StandardOptions.cpp

@@ -14,16 +14,16 @@ namespace {
 	Appends a Boolean selection of @c selection for option @c name to @c selection_set.
 */
 void append_bool(Configurable::SelectionSet &selection_set, const std::string &name, bool selection) {
-	selection_set[name] = std::unique_ptr<Configurable::Selection>(new Configurable::BooleanSelection(selection));
+	selection_set[name] = std::make_unique<Configurable::BooleanSelection>(selection);
 }
 
 /*!
 	Enquires for a Boolean selection for option @c name from @c selections_by_option, storing it to @c result if found.
 */
 bool get_bool(const Configurable::SelectionSet &selections_by_option, const std::string &name, bool &result) {
-	auto quickload = Configurable::selection<Configurable::BooleanSelection>(selections_by_option, "quickload");
+	auto selection = Configurable::selection<Configurable::BooleanSelection>(selections_by_option, name);
-	if(!quickload) return false;
+	if(!selection) return false;
-	result = quickload->value;
+	result = selection->value;
 	return true;
 }
 
@@ -42,6 +42,7 @@ std::vector<std::unique_ptr<Configurable::Option>> Configurable::standard_option
 		options.emplace_back(new Configurable::ListOption("Display", "display", display_options));
 	}
 	if(mask & AutomaticTapeMotorControl)	options.emplace_back(new Configurable::BooleanOption("Automatic Tape Motor Control", "autotapemotor"));
+	if(mask & QuickBoot)					options.emplace_back(new Configurable::BooleanOption("Boot Quickly", "quickboot"));
 	return options;
 }
 
@@ -63,7 +64,11 @@ void Configurable::append_display_selection(Configurable::SelectionSet &selectio
 		case Display::CompositeMonochrome:	string_selection = "composite-mono";	break;
 		case Display::CompositeColour:		string_selection = "composite";			break;
 	}
-	selection_set["display"] = std::unique_ptr<Configurable::Selection>(new Configurable::ListSelection(string_selection));
+	selection_set["display"] = std::make_unique<Configurable::ListSelection>(string_selection);
+}
+
+void Configurable::append_quick_boot_selection(Configurable::SelectionSet &selection_set, bool selection) {
+	append_bool(selection_set, "quickboot", selection);
 }
 
 // MARK: - Selection parsers
@@ -97,3 +102,7 @@ bool Configurable::get_display(const Configurable::SelectionSet &selections_by_o
 	}
 	return false;
 }
+
+bool Configurable::get_quick_boot(const Configurable::SelectionSet &selections_by_option, bool &result) {
+	return get_bool(selections_by_option, "quickboot", result);
+}

Configurable/StandardOptions.hpp

@@ -19,7 +19,8 @@ enum StandardOptions {
 	DisplayCompositeColour		= (1 << 2),
 	DisplayCompositeMonochrome	= (1 << 3),
 	QuickLoadTape				= (1 << 4),
-	AutomaticTapeMotorControl	= (1 << 5)
+	AutomaticTapeMotorControl	= (1 << 5),
+	QuickBoot					= (1 << 6),
 };
 
 enum class Display {
@@ -49,6 +50,11 @@ void append_automatic_tape_motor_control_selection(SelectionSet &selection_set,
 */
 void append_display_selection(SelectionSet &selection_set, Display selection);
 
+/*!
+	Appends to @c selection_set a selection of @c selection for QuickBoot.
+*/
+void append_quick_boot_selection(SelectionSet &selection_set, bool selection);
+
 /*!
 	Attempts to discern a QuickLoadTape selection from @c selections_by_option.
  
@@ -76,6 +82,15 @@ bool get_automatic_tape_motor_control_selection(const SelectionSet &selections_b
 */
 bool get_display(const SelectionSet &selections_by_option, Display &result);
 
+/*!
+	Attempts to QuickBoot a QuickLoadTape selection from @c selections_by_option.
+
+	@param selections_by_option The user selections.
+	@param result The location to which the selection will be stored if found.
+	@returns @c true if a selection is found; @c false otherwise.
+*/
+bool get_quick_boot(const SelectionSet &selections_by_option, bool &result);
+
 }
 
 #endif /* StandardOptions_hpp */

Inputs/Joystick.hpp

@@ -170,11 +170,11 @@ class ConcreteJoystick: public Joystick {
 			}
 		}
 
-		std::vector<Input> &get_inputs() override final {
+		std::vector<Input> &get_inputs() final {
 			return inputs_;
 		}
 
-		void set_input(const Input &input, bool is_active) override final {
+		void set_input(const Input &input, bool is_active) final {
 			// If this is a digital setting to a digital property, just pass it along.
 			if(input.is_button() || stick_types_[input.info.control.index] == StickType::Digital) {
 				did_set_input(input, is_active);
@@ -193,7 +193,7 @@ class ConcreteJoystick: public Joystick {
 			}
 		}
 
-		void set_input(const Input &input, float value) override final {
+		void set_input(const Input &input, float value) final {
 			// If this is an analogue setting to an analogue property, just pass it along.
 			if(!input.is_button() && stick_types_[input.info.control.index] == StickType::Analogue) {
 				did_set_input(input, value);

Inputs/Keyboard.cpp

@@ -10,13 +10,14 @@
 
 using namespace Inputs;
 
-Keyboard::Keyboard() {
+Keyboard::Keyboard(const std::set<Key> &essential_modifiers) : essential_modifiers_(essential_modifiers) {
 	for(int k = 0; k < int(Key::Help); ++k) {
 		observed_keys_.insert(Key(k));
 	}
 }
 
-Keyboard::Keyboard(const std::set<Key> &observed_keys) : observed_keys_(observed_keys), is_exclusive_(false) {}
+Keyboard::Keyboard(const std::set<Key> &observed_keys, const std::set<Key> &essential_modifiers) :
+	observed_keys_(observed_keys), essential_modifiers_(essential_modifiers), is_exclusive_(false) {}
 
 void Keyboard::set_key_pressed(Key key, char value, bool is_pressed) {
 	std::size_t key_offset = static_cast<std::size_t>(key);
@@ -28,6 +29,10 @@ void Keyboard::set_key_pressed(Key key, char value, bool is_pressed) {
 	if(delegate_) delegate_->keyboard_did_change_key(this, key, is_pressed);
 }
 
+const std::set<Inputs::Keyboard::Key> &Keyboard::get_essential_modifiers() {
+	return essential_modifiers_;
+}
+
 void Keyboard::reset_all_keys() {
 	std::fill(key_states_.begin(), key_states_.end(), false);
 	if(delegate_) delegate_->reset_all_keys(this);

Inputs/Keyboard.hpp

@@ -23,26 +23,26 @@ class Keyboard {
 	public:
 		enum class Key {
 			Escape, F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12, PrintScreen, ScrollLock, Pause,
-			BackTick, k1, k2, k3, k4, k5, k6, k7, k8, k9, k0, Hyphen, Equals, BackSpace,
+			BackTick, k1, k2, k3, k4, k5, k6, k7, k8, k9, k0, Hyphen, Equals, Backspace,
-			Tab, Q, W, E, R, T, Y, U, I, O, P, OpenSquareBracket, CloseSquareBracket, BackSlash,
+			Tab, Q, W, E, R, T, Y, U, I, O, P, OpenSquareBracket, CloseSquareBracket, Backslash,
 			CapsLock, A, S, D, F, G, H, J, K, L, Semicolon, Quote, Hash, Enter,
 			LeftShift, Z, X, C, V, B, N, M, Comma, FullStop, ForwardSlash, RightShift,
 			LeftControl, LeftOption, LeftMeta, Space, RightMeta, RightOption, RightControl,
 			Left, Right, Up, Down,
 			Insert, Home, PageUp, Delete, End, PageDown,
-			NumLock, KeyPadSlash, KeyPadAsterisk, KeyPadDelete,
+			NumLock, KeypadSlash, KeypadAsterisk, KeypadDelete,
-			KeyPad7, KeyPad8, KeyPad9, KeyPadPlus,
+			Keypad7, Keypad8, Keypad9, KeypadPlus,
-			KeyPad4, KeyPad5, KeyPad6, KeyPadMinus,
+			Keypad4, Keypad5, Keypad6, KeypadMinus,
-			KeyPad1, KeyPad2, KeyPad3, KeyPadEnter,
+			Keypad1, Keypad2, Keypad3, KeypadEnter,
-			KeyPad0, KeyPadDecimalPoint, KeyPadEquals,
+			Keypad0, KeypadDecimalPoint, KeypadEquals,
 			Help
 		};
 
 		/// Constructs a Keyboard that declares itself to observe all keys.
-		Keyboard();
+		Keyboard(const std::set<Key> &essential_modifiers = {});
 
 		/// Constructs a Keyboard that declares itself to observe only members of @c observed_keys.
-		Keyboard(const std::set<Key> &observed_keys);
+		Keyboard(const std::set<Key> &observed_keys, const std::set<Key> &essential_modifiers);
 
 		// Host interface.
 		virtual void set_key_pressed(Key key, char value, bool is_pressed);
@@ -51,10 +51,18 @@ class Keyboard {
 		/// @returns a set of all Keys that this keyboard responds to.
 		virtual const std::set<Key> &observed_keys();
 
-		/*
+		/// @returns the list of modifiers that this keyboard considers 'essential' (i.e. both mapped and highly used).
+		virtual const std::set<Inputs::Keyboard::Key> &get_essential_modifiers();
+
+		/*!
 			@returns @c true if this keyboard, on its original machine, looked
 			like a complete keyboard — i.e. if a user would expect this keyboard
 			to be the only thing a real keyboard maps to.
+
+			So this would be true of something like the Amstrad CPC, which has a full
+			keyboard, but it would be false of something like the Sega Master System
+			which has some buttons that you'd expect an emulator to map to its host
+			keyboard but which does not offer a full keyboard.
 		*/
 		virtual bool is_exclusive();
 
@@ -68,6 +76,7 @@ class Keyboard {
 
 	private:
 		std::set<Key> observed_keys_;
+		std::set<Key> essential_modifiers_;
 		std::vector<bool> key_states_;
 		Delegate *delegate_ = nullptr;
 		bool is_exclusive_ = true;

Inputs/QuadratureMouse/QuadratureMouse.hpp

@@ -34,24 +34,24 @@ class QuadratureMouse: public Mouse {
 		/*
 			Inputs, to satisfy the Mouse interface.
 		*/
-		void move(int x, int y) override {
+		void move(int x, int y) final {
 			// Accumulate all provided motion.
 			axes_[0] += x;
 			axes_[1] += y;
 		}
 
-		int get_number_of_buttons() override {
+		int get_number_of_buttons() final {
 			return number_of_buttons_;
 		}
 
-		void set_button_pressed(int index, bool is_pressed) override {
+		void set_button_pressed(int index, bool is_pressed) final {
 			if(is_pressed)
 				button_flags_ |= (1 << index);
 			else
 				button_flags_ &= ~(1 << index);
 		}
 
-		void reset_all_buttons() override {
+		void reset_all_buttons() final {
 			button_flags_ = 0;
 		}
 

Machines/AmstradCPC/AmstradCPC.cpp

@@ -41,7 +41,7 @@ namespace AmstradCPC {
 
 std::vector<std::unique_ptr<Configurable::Option>> get_options() {
 	return Configurable::standard_options(
-		static_cast<Configurable::StandardOptions>(Configurable::DisplayRGB | Configurable::DisplayCompositeColour)
+		Configurable::StandardOptions(Configurable::DisplayRGB | Configurable::DisplayCompositeColour)
 	);
 }
 
@@ -124,8 +124,11 @@ class InterruptTimer {
 class AYDeferrer {
 	public:
 		/// Constructs a new AY instance and sets its clock rate.
-		AYDeferrer() : ay_(audio_queue_), speaker_(ay_) {
+		AYDeferrer() : ay_(GI::AY38910::Personality::AY38910, audio_queue_), speaker_(ay_) {
 			speaker_.set_input_rate(1000000);
+			// Per the CPC Wiki:
+			// "A is output to the right, channel C is output left, and channel B is output to both left and right".
+			ay_.set_output_mixing(0.0, 0.5, 1.0, 1.0, 0.5, 0.0);
 		}
 
 		~AYDeferrer() {
@@ -153,14 +156,14 @@ class AYDeferrer {
 		}
 
 		/// @returns the AY itself.
-		GI::AY38910::AY38910 &ay() {
+		GI::AY38910::AY38910<true> &ay() {
 			return ay_;
 		}
 
 	private:
 		Concurrency::DeferringAsyncTaskQueue audio_queue_;
-		GI::AY38910::AY38910 ay_;
+		GI::AY38910::AY38910<true> ay_;
-		Outputs::Speaker::LowpassSpeaker<GI::AY38910::AY38910> speaker_;
+		Outputs::Speaker::LowpassSpeaker<GI::AY38910::AY38910<true>> speaker_;
 		HalfCycles cycles_since_update_;
 };
 
@@ -171,7 +174,7 @@ class AYDeferrer {
 */
 class CRTCBusHandler {
 	public:
-		CRTCBusHandler(uint8_t *ram, InterruptTimer &interrupt_timer) :
+		CRTCBusHandler(const uint8_t *ram, InterruptTimer &interrupt_timer) :
 			crt_(1024, 1, Outputs::Display::Type::PAL50, Outputs::Display::InputDataType::Red2Green2Blue2),
 			ram_(ram),
 			interrupt_timer_(interrupt_timer) {
@@ -249,44 +252,46 @@ class CRTCBusHandler {
 					// the CPC shuffles output lines as:
 					//	MA13 MA12	RA2 RA1 RA0		MA9 MA8 MA7 MA6 MA5 MA4 MA3 MA2 MA1 MA0		CCLK
 					// ... so form the real access address.
-					uint16_t address =
+					const uint16_t address =
-						static_cast<uint16_t>(
+						uint16_t(
 							((state.refresh_address & 0x3ff) << 1) |
 							((state.row_address & 0x7) << 11) |
 							((state.refresh_address & 0x3000) << 2)
 						);
 
-					// fetch two bytes and translate into pixels
+					// Fetch two bytes and translate into pixels. Guaranteed: the mode can change only at
+					// hsync, so there's no risk of pixel_pointer_ overrunning 320 output pixels without
+					// exactly reaching 320 output pixels.
 					switch(mode_) {
 						case 0:
 							reinterpret_cast<uint16_t *>(pixel_pointer_)[0] = mode0_output_[ram_[address]];
 							reinterpret_cast<uint16_t *>(pixel_pointer_)[1] = mode0_output_[ram_[address+1]];
-							pixel_pointer_ += 4;
+							pixel_pointer_ += 2 * sizeof(uint16_t);
 						break;
 
 						case 1:
 							reinterpret_cast<uint32_t *>(pixel_pointer_)[0] = mode1_output_[ram_[address]];
 							reinterpret_cast<uint32_t *>(pixel_pointer_)[1] = mode1_output_[ram_[address+1]];
-							pixel_pointer_ += 8;
+							pixel_pointer_ += 2 * sizeof(uint32_t);
 						break;
 
 						case 2:
 							reinterpret_cast<uint64_t *>(pixel_pointer_)[0] = mode2_output_[ram_[address]];
 							reinterpret_cast<uint64_t *>(pixel_pointer_)[1] = mode2_output_[ram_[address+1]];
-							pixel_pointer_ += 16;
+							pixel_pointer_ += 2 * sizeof(uint64_t);
 						break;
 
 						case 3:
 							reinterpret_cast<uint16_t *>(pixel_pointer_)[0] = mode3_output_[ram_[address]];
 							reinterpret_cast<uint16_t *>(pixel_pointer_)[1] = mode3_output_[ram_[address+1]];
-							pixel_pointer_ += 4;
+							pixel_pointer_ += 2 * sizeof(uint16_t);
 						break;
 
 					}
 
-					// flush the current buffer pixel if full; the CRTC allows many different display
+					// Flush the current buffer pixel if full; the CRTC allows many different display
 					// widths so it's not necessarily possible to predict the correct number in advance
-					// and using the upper bound could lead to inefficient behaviour
+					// and using the upper bound could lead to inefficient behaviour.
 					if(pixel_pointer_ == pixel_data_ + 320) {
 						crt_.output_data(cycles_ * 16, size_t(cycles_ * 16 / pixel_divider_));
 						pixel_pointer_ = pixel_data_ = nullptr;
@@ -333,6 +338,11 @@ class CRTCBusHandler {
 			crt_.set_scan_target(scan_target);
 		}
 
+		/// @returns The current scan status.
+		Outputs::Display::ScanStatus get_scaled_scan_status() const {
+			return crt_.get_scaled_scan_status() / 4.0f;
+		}
+
 		/// Sets the type of display.
 		void set_display_type(Outputs::Display::DisplayType display_type) {
 			crt_.set_display_type(display_type);
@@ -369,9 +379,17 @@ class CRTCBusHandler {
 
 	private:
 		void output_border(int length) {
-			uint8_t *colour_pointer = static_cast<uint8_t *>(crt_.begin_data(1));
+			assert(length >= 0);
+
+			// A black border can be output via crt_.output_blank for a minor performance
+			// win; otherwise paint whatever the border colour really is.
+			if(border_) {
+				uint8_t *const colour_pointer = static_cast<uint8_t *>(crt_.begin_data(1));
 				if(colour_pointer) *colour_pointer = border_;
 				crt_.output_level(length * 16);
+			} else {
+				crt_.output_blank(length * 16);
+			}
 		}
 
 #define Mode0Colour0(c) ((c & 0x80) >> 7) | ((c & 0x20) >> 3) | ((c & 0x08) >> 2) | ((c & 0x02) << 2)
@@ -387,16 +405,16 @@ class CRTCBusHandler {
 
 		void establish_palette_hits() {
 			for(int c = 0; c < 256; c++) {
-				mode0_palette_hits_[Mode0Colour0(c)].push_back(static_cast<uint8_t>(c));
+				mode0_palette_hits_[Mode0Colour0(c)].push_back(uint8_t(c));
-				mode0_palette_hits_[Mode0Colour1(c)].push_back(static_cast<uint8_t>(c));
+				mode0_palette_hits_[Mode0Colour1(c)].push_back(uint8_t(c));
 
-				mode1_palette_hits_[Mode1Colour0(c)].push_back(static_cast<uint8_t>(c));
+				mode1_palette_hits_[Mode1Colour0(c)].push_back(uint8_t(c));
-				mode1_palette_hits_[Mode1Colour1(c)].push_back(static_cast<uint8_t>(c));
+				mode1_palette_hits_[Mode1Colour1(c)].push_back(uint8_t(c));
-				mode1_palette_hits_[Mode1Colour2(c)].push_back(static_cast<uint8_t>(c));
+				mode1_palette_hits_[Mode1Colour2(c)].push_back(uint8_t(c));
-				mode1_palette_hits_[Mode1Colour3(c)].push_back(static_cast<uint8_t>(c));
+				mode1_palette_hits_[Mode1Colour3(c)].push_back(uint8_t(c));
 
-				mode3_palette_hits_[Mode3Colour0(c)].push_back(static_cast<uint8_t>(c));
+				mode3_palette_hits_[Mode3Colour0(c)].push_back(uint8_t(c));
-				mode3_palette_hits_[Mode3Colour1(c)].push_back(static_cast<uint8_t>(c));
+				mode3_palette_hits_[Mode3Colour1(c)].push_back(uint8_t(c));
 			}
 		}
 
@@ -406,7 +424,7 @@ class CRTCBusHandler {
 					// Mode 0: abcdefgh -> [gcea] [hdfb]
 					for(int c = 0; c < 256; c++) {
 						// prepare mode 0
-						uint8_t *mode0_pixels = reinterpret_cast<uint8_t *>(&mode0_output_[c]);
+						uint8_t *const mode0_pixels = reinterpret_cast<uint8_t *>(&mode0_output_[c]);
 						mode0_pixels[0] = palette_[Mode0Colour0(c)];
 						mode0_pixels[1] = palette_[Mode0Colour1(c)];
 					}
@@ -415,7 +433,7 @@ class CRTCBusHandler {
 				case 1:
 					for(int c = 0; c < 256; c++) {
 						// prepare mode 1
-						uint8_t *mode1_pixels = reinterpret_cast<uint8_t *>(&mode1_output_[c]);
+						uint8_t *const mode1_pixels = reinterpret_cast<uint8_t *>(&mode1_output_[c]);
 						mode1_pixels[0] = palette_[Mode1Colour0(c)];
 						mode1_pixels[1] = palette_[Mode1Colour1(c)];
 						mode1_pixels[2] = palette_[Mode1Colour2(c)];
@@ -426,7 +444,7 @@ class CRTCBusHandler {
 				case 2:
 					for(int c = 0; c < 256; c++) {
 						// prepare mode 2
-						uint8_t *mode2_pixels = reinterpret_cast<uint8_t *>(&mode2_output_[c]);
+						uint8_t *const mode2_pixels = reinterpret_cast<uint8_t *>(&mode2_output_[c]);
 						mode2_pixels[0] = palette_[((c & 0x80) >> 7)];
 						mode2_pixels[1] = palette_[((c & 0x40) >> 6)];
 						mode2_pixels[2] = palette_[((c & 0x20) >> 5)];
@@ -441,7 +459,7 @@ class CRTCBusHandler {
 				case 3:
 					for(int c = 0; c < 256; c++) {
 						// prepare mode 3
-						uint8_t *mode3_pixels = reinterpret_cast<uint8_t *>(&mode3_output_[c]);
+						uint8_t *const mode3_pixels = reinterpret_cast<uint8_t *>(&mode3_output_[c]);
 						mode3_pixels[0] = palette_[Mode3Colour0(c)];
 						mode3_pixels[1] = palette_[Mode3Colour1(c)];
 					}
@@ -453,7 +471,7 @@ class CRTCBusHandler {
 			switch(mode_) {
 				case 0: {
 					for(uint8_t c : mode0_palette_hits_[pen]) {
-						uint8_t *mode0_pixels = reinterpret_cast<uint8_t *>(&mode0_output_[c]);
+						uint8_t *const mode0_pixels = reinterpret_cast<uint8_t *>(&mode0_output_[c]);
 						mode0_pixels[0] = palette_[Mode0Colour0(c)];
 						mode0_pixels[1] = palette_[Mode0Colour1(c)];
 					}
@@ -461,7 +479,7 @@ class CRTCBusHandler {
 				case 1:
 					if(pen > 3) return;
 					for(uint8_t c : mode1_palette_hits_[pen]) {
-						uint8_t *mode1_pixels = reinterpret_cast<uint8_t *>(&mode1_output_[c]);
+						uint8_t *const mode1_pixels = reinterpret_cast<uint8_t *>(&mode1_output_[c]);
 						mode1_pixels[0] = palette_[Mode1Colour0(c)];
 						mode1_pixels[1] = palette_[Mode1Colour1(c)];
 						mode1_pixels[2] = palette_[Mode1Colour2(c)];
@@ -478,7 +496,7 @@ class CRTCBusHandler {
 					if(pen > 3) return;
 					// Same argument applies here as to case 1, as the unused bits aren't masked out.
 					for(uint8_t c : mode3_palette_hits_[pen]) {
-						uint8_t *mode3_pixels = reinterpret_cast<uint8_t *>(&mode3_output_[c]);
+						uint8_t *const mode3_pixels = reinterpret_cast<uint8_t *>(&mode3_output_[c]);
 						mode3_pixels[0] = palette_[Mode3Colour0(c)];
 						mode3_pixels[1] = palette_[Mode3Colour1(c)];
 					}
@@ -499,7 +517,7 @@ class CRTCBusHandler {
 
 		uint8_t mapped_palette_value(uint8_t colour) {
 #define COL(r, g, b) (r << 4) | (g << 2) | b
-			static const uint8_t mapping[32] = {
+			constexpr uint8_t mapping[32] = {
 				COL(1, 1, 1),	COL(1, 1, 1),	COL(0, 2, 1),	COL(2, 2, 1),
 				COL(0, 0, 1),	COL(2, 0, 1),	COL(0, 1, 1),	COL(2, 1, 1),
 				COL(2, 0, 1),	COL(2, 2, 1),	COL(2, 2, 0),	COL(2, 2, 2),
@@ -528,7 +546,7 @@ class CRTCBusHandler {
 		Outputs::CRT::CRT crt_;
 		uint8_t *pixel_data_ = nullptr, *pixel_pointer_ = nullptr;
 
-		uint8_t *ram_ = nullptr;
+		const uint8_t *const ram_ = nullptr;
 
 		int next_mode_ = 2, mode_ = 2;
 
@@ -564,7 +582,7 @@ class KeyboardState: public GI::AY38910::PortHandler {
 			Sets the row currently being reported to the AY.
 		*/
 		void set_row(int row) {
-			row_ = static_cast<size_t>(row);
+			row_ = size_t(row);
 		}
 
 		/*!
@@ -583,7 +601,7 @@ class KeyboardState: public GI::AY38910::PortHandler {
 		*/
 		void set_is_pressed(bool is_pressed, int line, int key) {
 			int mask = 1 << key;
-			assert(static_cast<size_t>(line) < sizeof(rows_));
+			assert(size_t(line) < sizeof(rows_));
 			if(is_pressed) rows_[line] &= ~mask; else rows_[line] |= mask;
 		}
 
@@ -594,7 +612,7 @@ class KeyboardState: public GI::AY38910::PortHandler {
 			memset(rows_, 0xff, sizeof(rows_));
 		}
 
-		std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() {
+		const std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() {
 			return joysticks_;
 		}
 
@@ -617,7 +635,7 @@ class KeyboardState: public GI::AY38910::PortHandler {
 					}),
 					state_(state) {}
 
-				void did_set_input(const Input &input, bool is_active) override {
+				void did_set_input(const Input &input, bool is_active) final {
 					uint8_t mask = 0;
 					switch(input.type) {
 						default: return;
@@ -646,17 +664,15 @@ class KeyboardState: public GI::AY38910::PortHandler {
 class FDC: public Intel::i8272::i8272 {
 	private:
 		Intel::i8272::BusHandler bus_handler_;
-		std::shared_ptr<Storage::Disk::Drive> drive_;
 
 	public:
-		FDC() :
+		FDC() : i8272(bus_handler_, Cycles(8000000)) {
-			i8272(bus_handler_, Cycles(8000000)),
+			emplace_drive(8000000, 300, 1);
-			drive_(new Storage::Disk::Drive(8000000, 300, 1)) {
+			set_drive(1);
-			set_drive(drive_);
 		}
 
 		void set_motor_on(bool on) {
-			drive_->set_motor_on(on);
+			get_drive().set_motor_on(on);
 		}
 
 		void select_drive(int c) {
@@ -664,11 +680,11 @@ class FDC: public Intel::i8272::i8272 {
 		}
 
 		void set_disk(std::shared_ptr<Storage::Disk::Disk> disk, int drive) {
-			drive_->set_disk(disk);
+			get_drive().set_disk(disk);
 		}
 
 		void set_activity_observer(Activity::Observer *observer) {
-			drive_->set_activity_observer(observer, "Drive 1", true);
+			get_drive().set_activity_observer(observer, "Drive 1", true);
 		}
 };
 
@@ -816,8 +832,8 @@ template <bool has_fdc> class ConcreteMachine:
 			for(std::size_t index = 0; index < roms.size(); ++index) {
 				auto &data = roms[index];
 				if(!data) throw ROMMachine::Error::MissingROMs;
-				roms_[static_cast<int>(index)] = std::move(*data);
+				roms_[int(index)] = std::move(*data);
-				roms_[static_cast<int>(index)].resize(16384);
+				roms_[int(index)].resize(16384);
 			}
 
 			// Establish default memory map
@@ -862,13 +878,15 @@ template <bool has_fdc> class ConcreteMachine:
 
 			// TODO (in the player, not here): adapt it to accept an input clock rate and
 			// run_for as HalfCycles
-			if(!tape_player_is_sleeping_) tape_player_.run_for(cycle.length.as_int());
+			if(!tape_player_is_sleeping_) tape_player_.run_for(cycle.length.as_integral());
 
 			// Pump the AY
 			ay_.run_for(cycle.length);
 
+			if constexpr (has_fdc) {
 				// Clock the FDC, if connected, using a lazy scale by two
 				time_since_fdc_update_ += cycle.length;
+			}
 
 			// Update typing activity
 			if(typer_) typer_->run_for(cycle.length);
@@ -894,10 +912,12 @@ template <bool has_fdc> class ConcreteMachine:
 					}
 
 					// Check for an upper ROM selection
-					if(has_fdc && !(address&0x2000)) {
+					if constexpr (has_fdc) {
+						if(!(address&0x2000)) {
 							upper_rom_ = (*cycle.value == 7) ? ROMType::AMSDOS : ROMType::BASIC;
 							if(upper_rom_is_paged_) read_pointers_[3] = roms_[upper_rom_].data();
 						}
+					}
 
 					// Check for a CRTC access
 					if(!(address & 0x4000)) {
@@ -910,20 +930,22 @@ template <bool has_fdc> class ConcreteMachine:
 
 					// Check for an 8255 PIO access
 					if(!(address & 0x800)) {
-						i8255_.set_register((address >> 8) & 3, *cycle.value);
+						i8255_.write((address >> 8) & 3, *cycle.value);
 					}
 
+					if constexpr (has_fdc) {
 						// Check for an FDC access
-					if(has_fdc && (address & 0x580) == 0x100) {
+						if((address & 0x580) == 0x100) {
 							flush_fdc();
-						fdc_.set_register(address & 1, *cycle.value);
+							fdc_.write(address & 1, *cycle.value);
 						}
 
 						// Check for a disk motor access
-					if(has_fdc && !(address & 0x580)) {
+						if(!(address & 0x580)) {
 							flush_fdc();
 							fdc_.set_motor_on(!!(*cycle.value));
 						}
+					}
 				break;
 				case CPU::Z80::PartialMachineCycle::Input:
 					// Default to nothing answering
@@ -931,13 +953,15 @@ template <bool has_fdc> class ConcreteMachine:
 
 					// Check for a PIO access
 					if(!(address & 0x800)) {
-						*cycle.value &= i8255_.get_register((address >> 8) & 3);
+						*cycle.value &= i8255_.read((address >> 8) & 3);
 					}
 
 					// Check for an FDC access
-					if(has_fdc && (address & 0x580) == 0x100) {
+					if constexpr (has_fdc) {
+						if((address & 0x580) == 0x100) {
 							flush_fdc();
-						*cycle.value &= fdc_.get_register(address & 1);
+							*cycle.value &= fdc_.read(address & 1);
+						}
 					}
 
 					// Check for a CRTC access; the below is not a typo, the CRTC can be selected
@@ -984,26 +1008,31 @@ template <bool has_fdc> class ConcreteMachine:
 		}
 
 		/// A CRTMachine function; sets the destination for video.
-		void set_scan_target(Outputs::Display::ScanTarget *scan_target) override final {
+		void set_scan_target(Outputs::Display::ScanTarget *scan_target) final {
 			crtc_bus_handler_.set_scan_target(scan_target);
 		}
 
+		/// A CRTMachine function; returns the current scan status.
+		Outputs::Display::ScanStatus get_scaled_scan_status() const final {
+			return crtc_bus_handler_.get_scaled_scan_status();
+		}
+
 		/// A CRTMachine function; sets the output display type.
-		void set_display_type(Outputs::Display::DisplayType display_type) override final {
+		void set_display_type(Outputs::Display::DisplayType display_type) final {
 			crtc_bus_handler_.set_display_type(display_type);
 		}
 
 		/// @returns the speaker in use.
-		Outputs::Speaker::Speaker *get_speaker() override final {
+		Outputs::Speaker::Speaker *get_speaker() final {
 			return ay_.get_speaker();
 		}
 
 		/// Wires virtual-dispatched CRTMachine run_for requests to the static Z80 method.
-		void run_for(const Cycles cycles) override final {
+		void run_for(const Cycles cycles) final {
 			z80_.run_for(cycles);
 		}
 
-		bool insert_media(const Analyser::Static::Media &media) override final {
+		bool insert_media(const Analyser::Static::Media &media) final {
 			// If there are any tapes supplied, use the first of them.
 			if(!media.tapes.empty()) {
 				tape_player_.set_tape(media.tapes.front());
@@ -1020,70 +1049,70 @@ template <bool has_fdc> class ConcreteMachine:
 			return !media.tapes.empty() || (!media.disks.empty() && has_fdc);
 		}
 
-		void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference clocking) override final {
+		void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference clocking) final {
 			fdc_is_sleeping_ = fdc_.preferred_clocking() == ClockingHint::Preference::None;
 			tape_player_is_sleeping_ = tape_player_.preferred_clocking() == ClockingHint::Preference::None;
 		}
 
 		// MARK: - Keyboard
-		void type_string(const std::string &string) override final {
+		void type_string(const std::string &string) final {
 			std::unique_ptr<CharacterMapper> mapper(new CharacterMapper());
 			Utility::TypeRecipient::add_typer(string, std::move(mapper));
 		}
 
-		HalfCycles get_typer_delay() override final {
+		HalfCycles get_typer_delay() final {
 			return Cycles(4000000);	// Wait 1 second before typing.
 		}
 
-		HalfCycles get_typer_frequency() override final {
+		HalfCycles get_typer_frequency() final {
 			return Cycles(160000);	// Type one character per frame.
 		}
 
 		// See header; sets a key as either pressed or released.
-		void set_key_state(uint16_t key, bool isPressed) override final {
+		void set_key_state(uint16_t key, bool isPressed) final {
 			key_state_.set_is_pressed(isPressed, key >> 4, key & 7);
 		}
 
 		// See header; sets all keys to released.
-		void clear_all_keys() override final {
+		void clear_all_keys() final {
 			key_state_.clear_all_keys();
 		}
 
-		KeyboardMapper *get_keyboard_mapper() override {
+		KeyboardMapper *get_keyboard_mapper() final {
 			return &keyboard_mapper_;
 		}
 
 		// MARK: - Activity Source
-		void set_activity_observer(Activity::Observer *observer) override {
+		void set_activity_observer(Activity::Observer *observer) final {
-			if(has_fdc) fdc_.set_activity_observer(observer);
+			if constexpr (has_fdc) fdc_.set_activity_observer(observer);
 		}
 
 		// MARK: - Configuration options.
-		std::vector<std::unique_ptr<Configurable::Option>> get_options() override {
+		std::vector<std::unique_ptr<Configurable::Option>> get_options() final {
 			return AmstradCPC::get_options();
 		}
 
-		void set_selections(const Configurable::SelectionSet &selections_by_option) override {
+		void set_selections(const Configurable::SelectionSet &selections_by_option) final {
 			Configurable::Display display;
 			if(Configurable::get_display(selections_by_option, display)) {
 				set_video_signal_configurable(display);
 			}
 		}
 
-		Configurable::SelectionSet get_accurate_selections() override {
+		Configurable::SelectionSet get_accurate_selections() final {
 			Configurable::SelectionSet selection_set;
 			Configurable::append_display_selection(selection_set, Configurable::Display::RGB);
 			return selection_set;
 		}
 
-		Configurable::SelectionSet get_user_friendly_selections() override {
+		Configurable::SelectionSet get_user_friendly_selections() final {
 			Configurable::SelectionSet selection_set;
 			Configurable::append_display_selection(selection_set, Configurable::Display::RGB);
 			return selection_set;
 		}
 
 		// MARK: - Joysticks
-		std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() override {
+		const std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() final {
 			return key_state_.get_joysticks();
 		}
 
@@ -1145,12 +1174,14 @@ template <bool has_fdc> class ConcreteMachine:
 		FDC fdc_;
 		HalfCycles time_since_fdc_update_;
 		void flush_fdc() {
+			if constexpr (has_fdc) {
 				// Clock the FDC, if connected, using a lazy scale by two
-			if(has_fdc && !fdc_is_sleeping_) {
+				if(!fdc_is_sleeping_) {
-				fdc_.run_for(Cycles(time_since_fdc_update_.as_int()));
+					fdc_.run_for(Cycles(time_since_fdc_update_.as_integral()));
 				}
 				time_since_fdc_update_ = HalfCycles(0);
 			}
+		}
 
 		InterruptTimer interrupt_timer_;
 		Storage::Tape::BinaryTapePlayer tape_player_;

Machines/AmstradCPC/Keyboard.cpp

@@ -31,12 +31,12 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 		BIND(F11, KeyRightSquareBracket);
 		BIND(F12, KeyClear);
 
-		BIND(Hyphen, KeyMinus);		BIND(Equals, KeyCaret);		BIND(BackSpace, KeyDelete);
+		BIND(Hyphen, KeyMinus);		BIND(Equals, KeyCaret);		BIND(Backspace, KeyDelete);
 		BIND(Tab, KeyTab);
 
 		BIND(OpenSquareBracket, KeyAt);
 		BIND(CloseSquareBracket, KeyLeftSquareBracket);
-		BIND(BackSlash, KeyBackSlash);
+		BIND(Backslash, KeyBackSlash);
 
 		BIND(CapsLock, KeyCapsLock);
 		BIND(Semicolon, KeyColon);
@@ -57,19 +57,19 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 		BIND(Left, KeyLeft);	BIND(Right, KeyRight);
 		BIND(Up, KeyUp);		BIND(Down, KeyDown);
 
-		BIND(KeyPad0, KeyF0);
+		BIND(Keypad0, KeyF0);
-		BIND(KeyPad1, KeyF1);		BIND(KeyPad2, KeyF2);		BIND(KeyPad3, KeyF3);
+		BIND(Keypad1, KeyF1);		BIND(Keypad2, KeyF2);		BIND(Keypad3, KeyF3);
-		BIND(KeyPad4, KeyF4);		BIND(KeyPad5, KeyF5);		BIND(KeyPad6, KeyF6);
+		BIND(Keypad4, KeyF4);		BIND(Keypad5, KeyF5);		BIND(Keypad6, KeyF6);
-		BIND(KeyPad7, KeyF7);		BIND(KeyPad8, KeyF8);		BIND(KeyPad9, KeyF9);
+		BIND(Keypad7, KeyF7);		BIND(Keypad8, KeyF8);		BIND(Keypad9, KeyF9);
-		BIND(KeyPadPlus, KeySemicolon);
+		BIND(KeypadPlus, KeySemicolon);
-		BIND(KeyPadMinus, KeyMinus);
+		BIND(KeypadMinus, KeyMinus);
 
-		BIND(KeyPadEnter, KeyEnter);
+		BIND(KeypadEnter, KeyEnter);
-		BIND(KeyPadDecimalPoint, KeyFullStop);
+		BIND(KeypadDecimalPoint, KeyFullStop);
-		BIND(KeyPadEquals, KeyMinus);
+		BIND(KeypadEquals, KeyMinus);
-		BIND(KeyPadSlash, KeyForwardSlash);
+		BIND(KeypadSlash, KeyForwardSlash);
-		BIND(KeyPadAsterisk, KeyColon);
+		BIND(KeypadAsterisk, KeyColon);
-		BIND(KeyPadDelete, KeyDelete);
+		BIND(KeypadDelete, KeyDelete);
 	}
 #undef BIND
 }

Machines/Apple/AppleII/AppleII.cpp

@@ -79,14 +79,16 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 		void update_video() {
 			video_.run_for(cycles_since_video_update_.flush<Cycles>());
 		}
-		static const int audio_divider = 8;
+		static constexpr int audio_divider = 8;
 		void update_audio() {
 			speaker_.run_for(audio_queue_, cycles_since_audio_update_.divide(Cycles(audio_divider)));
 		}
 		void update_just_in_time_cards() {
+			if(cycles_since_card_update_ > Cycles(0)) {
 				for(const auto &card : just_in_time_cards_) {
 					card->run_for(cycles_since_card_update_, stretched_cycles_since_card_update_);
 				}
+			}
 			cycles_since_card_update_ = 0;
 			stretched_cycles_since_card_update_ = 0;
 		}
@@ -124,22 +126,28 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 			pick_card_messaging_group(card);
 		}
 
-		bool is_every_cycle_card(Apple::II::Card *card) {
+		bool is_every_cycle_card(const Apple::II::Card *card) {
 			return !card->get_select_constraints();
 		}
 
+		bool card_lists_are_dirty_ = true;
+		bool card_became_just_in_time_ = false;
 		void pick_card_messaging_group(Apple::II::Card *card) {
+			// Simplify to a card being either just-in-time or realtime.
+			// Don't worry about exactly what it's watching,
 			const bool is_every_cycle = is_every_cycle_card(card);
 			std::vector<Apple::II::Card *> &intended = is_every_cycle ? every_cycle_cards_ : just_in_time_cards_;
-			std::vector<Apple::II::Card *> &undesired = is_every_cycle ? just_in_time_cards_ : every_cycle_cards_;
 
+			// If the card is already in the proper group, stop.
 			if(std::find(intended.begin(), intended.end(), card) != intended.end()) return;
-			auto old_membership = std::find(undesired.begin(), undesired.end(), card);
+
-			if(old_membership != undesired.end()) undesired.erase(old_membership);
+			// Otherwise, mark the sets as dirty. It isn't safe to transition the card here,
-			intended.push_back(card);
+			// as the main loop may be part way through iterating the two lists.
+			card_lists_are_dirty_ = true;
+			card_became_just_in_time_ |= !is_every_cycle;
 		}
 
-		void card_did_change_select_constraints(Apple::II::Card *card) override {
+		void card_did_change_select_constraints(Apple::II::Card *card) final {
 			pick_card_messaging_group(card);
 		}
 
@@ -275,12 +283,12 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 						Input(Input::Fire, 2),
 					}) {}
 
-					void did_set_input(const Input &input, float value) override {
+					void did_set_input(const Input &input, float value) final {
 						if(!input.info.control.index && (input.type == Input::Type::Horizontal || input.type == Input::Type::Vertical))
 							axes[(input.type == Input::Type::Horizontal) ? 0 : 1] = 1.0f - value;
 					}
 
-					void did_set_input(const Input &input, bool value) override {
+					void did_set_input(const Input &input, bool value) final {
 						if(input.type == Input::Type::Fire && input.info.control.index < 3) {
 							buttons[input.info.control.index] = value;
 						}
@@ -321,7 +329,7 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 			audio_toggle_(audio_queue_),
 			speaker_(audio_toggle_) {
 			// The system's master clock rate.
-			const float master_clock = 14318180.0;
+			constexpr float master_clock = 14318180.0;
 
 			// This is where things get slightly convoluted: establish the machine as having a clock rate
 			// equal to the number of cycles of work the 6502 will actually achieve. Which is less than
@@ -409,16 +417,20 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 			audio_queue_.flush();
 		}
 
-		void set_scan_target(Outputs::Display::ScanTarget *scan_target) override {
+		void set_scan_target(Outputs::Display::ScanTarget *scan_target) final {
 			video_.set_scan_target(scan_target);
 		}
 
+		Outputs::Display::ScanStatus get_scaled_scan_status() const final {
+			return video_.get_scaled_scan_status();
+		}
+
 		/// Sets the type of display.
-		void set_display_type(Outputs::Display::DisplayType display_type) override {
+		void set_display_type(Outputs::Display::DisplayType display_type) final {
 			video_.set_display_type(display_type);
 		}
 
-		Outputs::Speaker::Speaker *get_speaker() override {
+		Outputs::Speaker::Speaker *get_speaker() final {
 			return &speaker_;
 		}
 
@@ -753,6 +765,31 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 				}
 			}
 
+			// Update the card lists if any mutations are due.
+			if(card_lists_are_dirty_) {
+				card_lists_are_dirty_ = false;
+
+				// There's only one counter of time since update
+				// for just-in-time cards. If something new is
+				// transitioning, that needs to be zeroed.
+				if(card_became_just_in_time_) {
+					card_became_just_in_time_ = false;
+					update_just_in_time_cards();
+				}
+
+				// Clear the two lists and repopulate.
+				every_cycle_cards_.clear();
+				just_in_time_cards_.clear();
+				for(const auto &card: cards_) {
+					if(!card) continue;
+					if(is_every_cycle_card(card.get())) {
+						every_cycle_cards_.push_back(card.get());
+					} else {
+						just_in_time_cards_.push_back(card.get());
+					}
+				}
+			}
+
 			// Update analogue charge level.
 			analogue_charge_ = std::min(analogue_charge_ + 1.0f / 2820.0f, 1.1f);
 
@@ -766,15 +803,15 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 			audio_queue_.perform();
 		}
 
-		void run_for(const Cycles cycles) override {
+		void run_for(const Cycles cycles) final {
 			m6502_.run_for(cycles);
 		}
 
-		void reset_all_keys() override {
+		void reset_all_keys() final {
 			open_apple_is_pressed_ = closed_apple_is_pressed_ = key_is_down_ = false;
 		}
 
-		void set_key_pressed(Key key, char value, bool is_pressed) override {
+		void set_key_pressed(Key key, char value, bool is_pressed) final {
 			switch(key) {
 				default: break;
 				case Key::F12:
@@ -795,7 +832,7 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 					case Key::Right:		value = 0x15;	break;
 					case Key::Down:			value = 0x0a;	break;
 					case Key::Up:			value = 0x0b;	break;
-					case Key::BackSpace:	value = 0x7f;	break;
+					case Key::Backspace:	value = 0x7f;	break;
 					default: return;
 				}
 			}
@@ -813,38 +850,38 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 			}
 		}
 
-		Inputs::Keyboard &get_keyboard() override {
+		Inputs::Keyboard &get_keyboard() final {
 			return *this;
 		}
 
-		void type_string(const std::string &string) override {
+		void type_string(const std::string &string) final {
-			string_serialiser_.reset(new Utility::StringSerialiser(string, true));
+			string_serialiser_ = std::make_unique<Utility::StringSerialiser>(string, true);
 		}
 
 		// MARK:: Configuration options.
-		std::vector<std::unique_ptr<Configurable::Option>> get_options() override {
+		std::vector<std::unique_ptr<Configurable::Option>> get_options() final {
 			return Apple::II::get_options();
 		}
 
-		void set_selections(const Configurable::SelectionSet &selections_by_option) override {
+		void set_selections(const Configurable::SelectionSet &selections_by_option) final {
 			Configurable::Display display;
 			if(Configurable::get_display(selections_by_option, display)) {
 				set_video_signal_configurable(display);
 			}
 		}
 
-		Configurable::SelectionSet get_accurate_selections() override {
+		Configurable::SelectionSet get_accurate_selections() final {
 			Configurable::SelectionSet selection_set;
 			Configurable::append_display_selection(selection_set, Configurable::Display::CompositeColour);
 			return selection_set;
 		}
 
-		Configurable::SelectionSet get_user_friendly_selections() override {
+		Configurable::SelectionSet get_user_friendly_selections() final {
 			return get_accurate_selections();
 		}
 
 		// MARK: MediaTarget
-		bool insert_media(const Analyser::Static::Media &media) override {
+		bool insert_media(const Analyser::Static::Media &media) final {
 			if(!media.disks.empty()) {
 				auto diskii = diskii_card();
 				if(diskii) diskii->set_disk(media.disks[0], 0);
@@ -853,14 +890,14 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 		}
 
 		// MARK: Activity::Source
-		void set_activity_observer(Activity::Observer *observer) override {
+		void set_activity_observer(Activity::Observer *observer) final {
 			for(const auto &card: cards_) {
 				if(card) card->set_activity_observer(observer);
 			}
 		}
 
 		// MARK: JoystickMachine
-		std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() override {
+		const std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() final {
 			return joysticks_;
 		}
 };

Machines/Apple/AppleII/Card.hpp

@@ -83,10 +83,8 @@ class Card {
 			will receive a perform_bus_operation every cycle. To reduce the number of
 			virtual method calls, they **will not** receive run_for. run_for will propagate
 			only to cards that register for IO and/or Device accesses only.
-
-
 		*/
-		int get_select_constraints() {
+		int get_select_constraints() const {
 			return select_constraints_;
 		}
 

Machines/Apple/AppleII/DiskIICard.cpp

@@ -52,7 +52,7 @@ void DiskIICard::perform_bus_operation(Select select, bool is_read, uint16_t add
 
 void DiskIICard::run_for(Cycles cycles, int stretches) {
 	if(diskii_clocking_preference_ == ClockingHint::Preference::None) return;
-	diskii_.run_for(Cycles(cycles.as_int() * 2));
+	diskii_.run_for(Cycles(cycles.as_integral() * 2));
 }
 
 void DiskIICard::set_disk(const std::shared_ptr<Storage::Disk::Disk> &disk, int drive) {
@@ -65,7 +65,7 @@ void DiskIICard::set_activity_observer(Activity::Observer *observer) {
 
 void DiskIICard::set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference preference) {
 	diskii_clocking_preference_ = preference;
-	set_select_constraints((preference != ClockingHint::Preference::RealTime) ? (IO | Device) : 0);
+	set_select_constraints((preference != ClockingHint::Preference::RealTime) ? (IO | Device) : None);
 }
 
 Storage::Disk::Drive &DiskIICard::get_drive(int drive) {

Machines/Apple/AppleII/DiskIICard.hpp

@@ -27,16 +27,16 @@ class DiskIICard: public Card, public ClockingHint::Observer {
 	public:
 		DiskIICard(const ROMMachine::ROMFetcher &rom_fetcher, bool is_16_sector);
 
-		void perform_bus_operation(Select select, bool is_read, uint16_t address, uint8_t *value) override;
+		void perform_bus_operation(Select select, bool is_read, uint16_t address, uint8_t *value) final;
-		void run_for(Cycles cycles, int stretches) override;
+		void run_for(Cycles cycles, int stretches) final;
 
-		void set_activity_observer(Activity::Observer *observer) override;
+		void set_activity_observer(Activity::Observer *observer) final;
 
 		void set_disk(const std::shared_ptr<Storage::Disk::Disk> &disk, int drive);
 		Storage::Disk::Drive &get_drive(int drive);
 
 	private:
-		void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference clocking) override;
+		void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference clocking) final;
 		std::vector<uint8_t> boot_;
 		Apple::DiskII diskii_;
 		ClockingHint::Preference diskii_clocking_preference_ = ClockingHint::Preference::RealTime;

Machines/Apple/AppleII/Video.cpp

@@ -47,6 +47,10 @@ void VideoBase::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
 	crt_.set_scan_target(scan_target);
 }
 
+Outputs::Display::ScanStatus VideoBase::get_scaled_scan_status() const {
+	return crt_.get_scaled_scan_status() / 14.0f;
+}
+
 void VideoBase::set_display_type(Outputs::Display::DisplayType display_type) {
 	crt_.set_display_type(display_type);
 }
@@ -56,7 +60,7 @@ void VideoBase::set_display_type(Outputs::Display::DisplayType display_type) {
 */
 void VideoBase::set_alternative_character_set(bool alternative_character_set) {
 	set_alternative_character_set_ = alternative_character_set;
-	deferrer_.defer(Cycles(2), [=] {
+	deferrer_.defer(Cycles(2), [this, alternative_character_set] {
 		alternative_character_set_ = alternative_character_set;
 		if(alternative_character_set) {
 			character_zones[1].address_mask = 0xff;
@@ -74,7 +78,7 @@ bool VideoBase::get_alternative_character_set() {
 
 void VideoBase::set_80_columns(bool columns_80) {
 	set_columns_80_ = columns_80;
-	deferrer_.defer(Cycles(2), [=] {
+	deferrer_.defer(Cycles(2), [this, columns_80] {
 		columns_80_ = columns_80;
 	});
 }
@@ -101,7 +105,7 @@ bool VideoBase::get_page2() {
 
 void VideoBase::set_text(bool text) {
 	set_text_ = text;
-	deferrer_.defer(Cycles(2), [=] {
+	deferrer_.defer(Cycles(2), [this, text] {
 		text_ = text;
 	});
 }
@@ -112,7 +116,7 @@ bool VideoBase::get_text() {
 
 void VideoBase::set_mixed(bool mixed) {
 	set_mixed_ = mixed;
-	deferrer_.defer(Cycles(2), [=] {
+	deferrer_.defer(Cycles(2), [this, mixed] {
 		mixed_ = mixed;
 	});
 }
@@ -123,7 +127,7 @@ bool VideoBase::get_mixed() {
 
 void VideoBase::set_high_resolution(bool high_resolution) {
 	set_high_resolution_ = high_resolution;
-	deferrer_.defer(Cycles(2), [=] {
+	deferrer_.defer(Cycles(2), [this, high_resolution] {
 		high_resolution_ = high_resolution;
 	});
 }
@@ -134,7 +138,7 @@ bool VideoBase::get_high_resolution() {
 
 void VideoBase::set_annunciator_3(bool annunciator_3) {
 	set_annunciator_3_ = annunciator_3;
-	deferrer_.defer(Cycles(2), [=] {
+	deferrer_.defer(Cycles(2), [this, annunciator_3] {
 		annunciator_3_ = annunciator_3;
 		high_resolution_mask_ = annunciator_3_ ? 0x7f : 0xff;
 	});

Machines/Apple/AppleII/Video.hpp

@@ -40,6 +40,9 @@ class VideoBase {
 		/// Sets the scan target.
 		void set_scan_target(Outputs::Display::ScanTarget *scan_target);
 
+		/// Gets the current scan status.
+		Outputs::Display::ScanStatus get_scaled_scan_status() const;
+
 		/// Sets the type of output.
 		void set_display_type(Outputs::Display::DisplayType);
 
@@ -203,7 +206,7 @@ class VideoBase {
 		std::array<uint8_t, 40> auxiliary_stream_;
 
 		bool is_iie_ = false;
-		static const int flash_length = 8406;
+		static constexpr int flash_length = 8406;
 
 		// Describes the current text mode mapping from in-memory character index
 		// to output character.
@@ -252,14 +255,14 @@ class VideoBase {
 		void output_fat_low_resolution(uint8_t *target, const uint8_t *source, size_t length, int column, int row) const;
 
 		// Maintain a DeferredQueue for delayed mode switches.
-		DeferredQueue<Cycles> deferrer_;
+		DeferredQueuePerformer<Cycles> deferrer_;
 };
 
 template <class BusHandler, bool is_iie> class Video: public VideoBase {
 	public:
 		/// Constructs an instance of the video feed; a CRT is also created.
 		Video(BusHandler &bus_handler) :
-			VideoBase(is_iie, [=] (Cycles cycles) { advance(cycles); }),
+			VideoBase(is_iie, [this] (Cycles cycles) { advance(cycles); }),
 			bus_handler_(bus_handler) {}
 
 		/*!
@@ -284,7 +287,7 @@ template <class BusHandler, bool is_iie> class Video: public VideoBase {
 			// Source: Have an Apple Split by Bob Bishop; http://rich12345.tripod.com/aiivideo/softalk.html
 
 			// Determine column at offset.
-			int mapped_column = column_ + offset.as_int();
+			int mapped_column = column_ + int(offset.as_integral());
 
 			// Map that backwards from the internal pixels-at-start generation to pixels-at-end
 			// (so what was column 0 is now column 25).
@@ -315,7 +318,7 @@ template <class BusHandler, bool is_iie> class Video: public VideoBase {
 		bool get_is_vertical_blank(Cycles offset) {
 			// Map that backwards from the internal pixels-at-start generation to pixels-at-end
 			// (so what was column 0 is now column 25).
-			int mapped_column = column_ + offset.as_int();
+			int mapped_column = column_ + int(offset.as_integral());
 
 			// Map that backwards from the internal pixels-at-start generation to pixels-at-end
 			// (so what was column 0 is now column 25).
@@ -339,11 +342,11 @@ template <class BusHandler, bool is_iie> class Video: public VideoBase {
 
 				A frame is oriented around 65 cycles across, 262 lines down.
 			*/
-			static const int first_sync_line = 220;		// A complete guess. Information needed.
+			constexpr int first_sync_line = 220;		// A complete guess. Information needed.
-			static const int first_sync_column = 49;	// Also a guess.
+			constexpr int first_sync_column = 49;	// Also a guess.
-			static const int sync_length = 4;			// One of the two likely candidates.
+			constexpr int sync_length = 4;			// One of the two likely candidates.
 
-			int int_cycles = cycles.as_int();
+			int int_cycles = int(cycles.as_integral());
 			while(int_cycles) {
 				const int cycles_this_line = std::min(65 - column_, int_cycles);
 				const int ending_column = column_ + cycles_this_line;

Machines/Apple/Macintosh/Audio.cpp

@@ -35,7 +35,7 @@ void Audio::set_volume(int volume) {
 	posted_volume_ = volume;
 
 	// Post the volume change as a deferred event.
-	task_queue_.defer([=] () {
+	task_queue_.defer([this, volume] () {
 		volume_ = volume;
 		set_volume_multiplier();
 	});
@@ -47,7 +47,7 @@ void Audio::set_enabled(bool on) {
 	posted_enable_mask_ = int(on);
 
 	// Post the enabled mask change as a deferred event.
-	task_queue_.defer([=] () {
+	task_queue_.defer([this, on] () {
 		enabled_mask_ = int(on);
 		set_volume_multiplier();
 	});

Machines/Apple/Macintosh/Audio.hpp

@@ -55,6 +55,7 @@ class Audio: public ::Outputs::Speaker::SampleSource {
 		void get_samples(std::size_t number_of_samples, int16_t *target);
 		bool is_zero_level();
 		void set_sample_volume_range(std::int16_t range);
+		constexpr static bool get_is_stereo() { return false; }
 
 	private:
 		Concurrency::DeferringAsyncTaskQueue &task_queue_;

Machines/Apple/Macintosh/DriveSpeedAccumulator.cpp

@@ -11,7 +11,7 @@
 using namespace Apple::Macintosh;
 
 void DriveSpeedAccumulator::post_sample(uint8_t sample) {
-	if(!number_of_drives_) return;
+	if(!delegate_) return;
 
 	// An Euler-esque approximation is used here: just collect all
 	// the samples until there is a certain small quantity of them,
@@ -50,14 +50,7 @@ void DriveSpeedAccumulator::post_sample(uint8_t sample) {
 		const float normalised_sum = float(sum) / float(samples_.size());
 		const float rotation_speed = (normalised_sum * 27.08f) - 259.0f;
 
-		for(int c = 0; c < number_of_drives_; ++c) {
+		delegate_->drive_speed_accumulator_set_drive_speed(this, rotation_speed);
-			drives_[c]->set_rotation_speed(rotation_speed);
-		}
-//		printf("RPM: %0.2f (%d sum)\n", rotation_speed, sum);
 	}
 }
 
-void DriveSpeedAccumulator::add_drive(Apple::Macintosh::DoubleDensityDrive *drive) {
-	drives_[number_of_drives_] = drive;
-	++number_of_drives_;
-}