Attempted to separate out the concept of a serial port and a serial bus, since the bus may be shared, and to establish half duplex communications from the Vic.

Machines/Commodore/SerialBus.cpp

@@ -0,0 +1,43 @@
+//
+//  SerialPort.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 05/07/2016.
+//  Copyright © 2016 Thomas Harte. All rights reserved.
+//
+
+#include "SerialBus.hpp"
+
+using namespace Commodore::Serial;
+
+void Bus::add_port(std::shared_ptr<Port> port)
+{
+	_ports.push_back(port);
+}
+
+void Bus::set_line_output_did_change(Line line)
+{
+	bool new_line_value = false;
+	for(std::weak_ptr<Port> port : _ports)
+	{
+		std::shared_ptr<Port> locked_port = port.lock();
+		if(locked_port)
+		{
+			new_line_value |= locked_port->get_output(line);
+		}
+	}
+
+	if(new_line_value != _line_values[line])
+	{
+		_line_values[line] = new_line_value;
+
+		for(std::weak_ptr<Port> port : _ports)
+		{
+			std::shared_ptr<Port> locked_port = port.lock();
+			if(locked_port)
+			{
+				locked_port->set_input(line, new_line_value);
+			}
+		}
+	}
+}

Machines/Commodore/SerialBus.hpp

@@ -0,0 +1,67 @@
+//
+//  SerialPort.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 05/07/2016.
+//  Copyright © 2016 Thomas Harte. All rights reserved.
+//
+
+#ifndef SerialBus_hpp
+#define SerialBus_hpp
+
+#import <vector>
+
+namespace Commodore {
+namespace Serial {
+
+	enum Line {
+		ServiceRequest = 0,
+		Attention,
+		Clock,
+		Data,
+		Reset
+	};
+
+	class Port;
+
+	class Bus {
+		public:
+			Bus() : _line_values{false, false, false, false, false} {}
+
+			void add_port(std::shared_ptr<Port> port);
+			void set_line_output_did_change(Line line);
+
+		private:
+			bool _line_values[5];
+			std::vector<std::weak_ptr<Port>> _ports;
+	};
+
+	class Port {
+		public:
+			Port() : _line_values{false, false, false, false, false} {}
+
+			void set_output(Line line, bool value) {
+				_line_values[line] = value;
+				std::shared_ptr<Bus> bus = _serial_bus.lock();
+				if(bus) bus->set_line_output_did_change(line);
+			}
+
+			bool get_output(Line line) {
+				return _line_values[line];
+			}
+
+			virtual void set_input(Line line, bool value) = 0;
+
+			inline void set_serial_bus(std::shared_ptr<Bus> serial_bus) {
+				_serial_bus = serial_bus;
+			}
+
+		private:
+			std::weak_ptr<Bus> _serial_bus;
+			bool _line_values[5];
+	};
+
+}
+}
+
+#endif /* SerialPort_hpp */

Machines/Commodore/Vic-20/Vic20.cpp

@@ -15,18 +15,27 @@ using namespace Commodore::Vic20;
 Machine::Machine() :
 	_rom(nullptr)
 {
+	// create 6522s, serial port and bus
 	_userPortVIA.reset(new UserPortVIA);
 	_keyboardVIA.reset(new KeyboardVIA);
 	_serialPort.reset(new SerialPort);
+	_serialBus.reset(new ::Commodore::Serial::Bus);
 
+	// wire up the serial bus and serial port
+	_serialBus->add_port(_serialPort);
+	_serialPort->set_serial_bus(_serialBus);
+
+	// wire up 6522s and serial port
 	_userPortVIA->set_serial_port(_serialPort);
 	_keyboardVIA->set_serial_port(_serialPort);
 	_serialPort->set_vias(_userPortVIA, _keyboardVIA);
 
+	// wire up the 6522s, tape and machine
 	_userPortVIA->set_delegate(this);
 	_keyboardVIA->set_delegate(this);
 	_tape.set_delegate(this);
 
+	// establish the memory maps
 	memset(_videoMemoryMap, 0, sizeof(_videoMemoryMap));
 	memset(_processorReadMemoryMap, 0, sizeof(_processorReadMemoryMap));
 	memset(_processorWriteMemoryMap, 0, sizeof(_processorWriteMemoryMap));
@@ -317,32 +326,7 @@ void Tape::process_input_pulse(Storage::Tape::Pulse pulse)
 
 #pragma mark - Serial Port
 
-void SerialPort::set_clock_output(bool value)
+void SerialPort::set_input(::Commodore::Serial::Line line, bool value)
 {
-	printf("Serial port clock output %s\n", value ? "on" : "off");
+	printf("Serial port line %d: %s\n", line, value ? "on" : "off");
-}
-
-void SerialPort::set_data_output(bool value)
-{
-	printf("Serial port data output %s\n", value ? "on" : "off");
-}
-
-void SerialPort::set_attention_output(bool value)
-{
-	printf("Serial port attention output %s\n", value ? "on" : "off");
-}
-
-void SerialPort::set_clock_input(bool value)
-{
-	printf("Serial port clock input %s\n", value ? "on" : "off");
-}
-
-void SerialPort::set_data_input(bool value)
-{
-	printf("Serial port data input %s\n", value ? "on" : "off");
-}
-
-void SerialPort::set_attention_input(bool value)
-{
-	printf("Serial port attention input %s\n", value ? "on" : "off");
 }

Machines/Commodore/Vic-20/Vic20.hpp

@@ -13,6 +13,7 @@
 #include "../../../Storage/Tape/Tape.hpp"
 #include "../../../Components/6560/6560.hpp"
 #include "../../../Components/6522/6522.hpp"
+#include "../SerialBus.hpp"
 
 #include "../../CRTMachine.hpp"
 #include "../../Typer.hpp"
@@ -26,7 +27,6 @@ enum ROMSlot {
 	ROMSlotCharacters,
 };
 
-
 #define key(line, mask) (((mask) << 3) | (line))
 
 enum Key: uint16_t {
@@ -61,15 +61,9 @@ enum JoystickInput {
 class UserPortVIA;
 class KeyboardVIA;
 
-class SerialPort {
+class SerialPort : public ::Commodore::Serial::Port {
 	public:
-		void set_clock_output(bool value);
+		void set_input(::Commodore::Serial::Line line, bool value);
-		void set_data_output(bool value);
-		void set_attention_output(bool value);
-
-		void set_clock_input(bool value);
-		void set_data_input(bool value);
-		void set_attention_input(bool value);
 
 		void set_vias(std::shared_ptr<UserPortVIA> userPortVIA, std::shared_ptr<KeyboardVIA> keyboardVIA) {
 			_userPortVIA = userPortVIA;
@@ -106,7 +100,7 @@ class UserPortVIA: public MOS::MOS6522<UserPortVIA>, public MOS::MOS6522IRQDeleg
 		void set_port_output(Port port, uint8_t value, uint8_t mask) {
 			if(!port) {
 				std::shared_ptr<SerialPort> serialPort = _serialPort.lock();
-				if(serialPort) serialPort->set_attention_output(!(value&0x80));
+				if(serialPort) serialPort->set_output(::Commodore::Serial::Line::Attention, !(value&0x80));
 			}
 		}
 
@@ -165,9 +159,9 @@ class KeyboardVIA: public MOS::MOS6522<KeyboardVIA>, public MOS::MOS6522IRQDeleg
 				std::shared_ptr<SerialPort> serialPort = _serialPort.lock();
 				if(serialPort) {
 					if(port == Port::A) {
-						serialPort->set_clock_output(value);
+						serialPort->set_output(::Commodore::Serial::Line::Clock, value);
 					} else {
-						serialPort->set_data_output(value);
+						serialPort->set_output(::Commodore::Serial::Line::Data, value);
 					}
 				}
 			}
@@ -287,6 +281,7 @@ class Machine:
 		std::shared_ptr<UserPortVIA> _userPortVIA;
 		std::shared_ptr<KeyboardVIA> _keyboardVIA;
 		std::shared_ptr<SerialPort> _serialPort;
+		std::shared_ptr<::Commodore::Serial::Bus> _serialBus;
 
 		// Tape
 		Tape _tape;

OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj

@@ -27,6 +27,7 @@
 		4B2E2D9D1C3A070400138695 /* Electron.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B2E2D9B1C3A070400138695 /* Electron.cpp */; };
 		4B4DC8211D2C2425003C5BF8 /* Vic20.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B4DC81F1D2C2425003C5BF8 /* Vic20.cpp */; };
 		4B4DC8281D2C2470003C5BF8 /* Commodore1540.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B4DC8261D2C2470003C5BF8 /* Commodore1540.cpp */; };
+		4B4DC82B1D2C27A4003C5BF8 /* SerialBus.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B4DC8291D2C27A4003C5BF8 /* SerialBus.cpp */; };
 		4B55CE581C3B7D360093A61B /* Atari2600Document.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B55CE561C3B7D360093A61B /* Atari2600Document.swift */; };
 		4B55CE591C3B7D360093A61B /* ElectronDocument.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B55CE571C3B7D360093A61B /* ElectronDocument.swift */; };
 		4B55CE5D1C3B7D6F0093A61B /* CSOpenGLView.m in Sources */ = {isa = PBXBuildFile; fileRef = 4B55CE5C1C3B7D6F0093A61B /* CSOpenGLView.m */; };
@@ -389,6 +390,8 @@
 		4B4DC8201D2C2425003C5BF8 /* Vic20.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = Vic20.hpp; sourceTree = "<group>"; };
 		4B4DC8261D2C2470003C5BF8 /* Commodore1540.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = Commodore1540.cpp; sourceTree = "<group>"; };
 		4B4DC8271D2C2470003C5BF8 /* Commodore1540.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = Commodore1540.hpp; sourceTree = "<group>"; };
+		4B4DC8291D2C27A4003C5BF8 /* SerialBus.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = SerialBus.cpp; sourceTree = "<group>"; };
+		4B4DC82A1D2C27A4003C5BF8 /* SerialBus.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = SerialBus.hpp; sourceTree = "<group>"; };
 		4B55CE561C3B7D360093A61B /* Atari2600Document.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Atari2600Document.swift; sourceTree = "<group>"; };
 		4B55CE571C3B7D360093A61B /* ElectronDocument.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ElectronDocument.swift; sourceTree = "<group>"; };
 		4B55CE5B1C3B7D6F0093A61B /* CSOpenGLView.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = CSOpenGLView.h; sourceTree = "<group>"; };
@@ -867,6 +870,8 @@
 			children = (
 				4B4DC8251D2C2470003C5BF8 /* 1540 */,
 				4B4DC81E1D2C2425003C5BF8 /* Vic-20 */,
+				4B4DC8291D2C27A4003C5BF8 /* SerialBus.cpp */,
+				4B4DC82A1D2C27A4003C5BF8 /* SerialBus.hpp */,
 			);
 			path = Commodore;
 			sourceTree = "<group>";
@@ -1801,6 +1806,7 @@
 				4BBF99151C8FBA6F0075DAFB /* CRTOpenGL.cpp in Sources */,
 				4B0CCC451C62D0B3001CAC5F /* CRT.cpp in Sources */,
 				4B55CE591C3B7D360093A61B /* ElectronDocument.swift in Sources */,
+				4B4DC82B1D2C27A4003C5BF8 /* SerialBus.cpp in Sources */,
 				4BC3B74F1CD194CC00F86E85 /* Shader.cpp in Sources */,
 				4B55CE581C3B7D360093A61B /* Atari2600Document.swift in Sources */,
 				4BBB14311CD2CECE00BDB55C /* IntermediateShader.cpp in Sources */,