A CRT is still absent but this moves the ball back into the C++ side's court.

Machines/Vic-20/Vic20.cpp

@@ -7,3 +7,10 @@
 //
 
 #include "Vic20.hpp"
+
+using namespace Vic20;
+
+unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value)
+{
+	return 1;
+}

Machines/Vic-20/Vic20.hpp

@@ -15,6 +15,17 @@
 namespace Vic20 {
 
 class Machine: public CPU6502::Processor<Machine>, public CRTMachine::Machine {
+	public:
+		// to satisfy CPU6502::Processor
+		unsigned int perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value);
+		void synchronise() {}
+
+		// to satisfy CRTMachine::Machine
+		virtual void setup_output(float aspect_ratio) {}
+		virtual void close_output() {}
+		virtual Outputs::CRT::CRT *get_crt() { return nullptr; }	// TODO
+		virtual Outputs::Speaker *get_speaker() { return nullptr; }	// TODO
+		virtual void run_for_cycles(int number_of_cycles) { CPU6502::Processor<Machine>::run_for_cycles(number_of_cycles); }
 };
 
 }

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

@@ -31,7 +31,7 @@
 		4B73C71A1D036BD90074D992 /* Vic20Document.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B73C7191D036BD90074D992 /* Vic20Document.swift */; };
 		4B73C71D1D036C030074D992 /* Vic20Document.xib in Resources */ = {isa = PBXBuildFile; fileRef = 4B73C71B1D036C030074D992 /* Vic20Document.xib */; };
 		4B886FF21D03B517004291C3 /* Vic20.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B886FF01D03B517004291C3 /* Vic20.cpp */; };
-		4B886FF51D03B61E004291C3 /* CSVic20.m in Sources */ = {isa = PBXBuildFile; fileRef = 4B886FF41D03B61E004291C3 /* CSVic20.m */; };
+		4B886FF51D03B61E004291C3 /* CSVic20.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4B886FF41D03B61E004291C3 /* CSVic20.mm */; };
 		4B92EACA1B7C112B00246143 /* TimingTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B92EAC91B7C112B00246143 /* TimingTests.swift */; };
 		4BB298EE1B587D8400A49093 /* 6502_functional_test.bin in Resources */ = {isa = PBXBuildFile; fileRef = 4BB297E01B587D8300A49093 /* 6502_functional_test.bin */; };
 		4BB298EF1B587D8400A49093 /* AllSuiteA.bin in Resources */ = {isa = PBXBuildFile; fileRef = 4BB297E11B587D8300A49093 /* AllSuiteA.bin */; };
@@ -382,7 +382,7 @@
 		4B886FF01D03B517004291C3 /* Vic20.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = Vic20.cpp; path = "Vic-20/Vic20.cpp"; sourceTree = "<group>"; };
 		4B886FF11D03B517004291C3 /* Vic20.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; name = Vic20.hpp; path = "Vic-20/Vic20.hpp"; sourceTree = "<group>"; };
 		4B886FF31D03B61E004291C3 /* CSVic20.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = CSVic20.h; sourceTree = "<group>"; };
-		4B886FF41D03B61E004291C3 /* CSVic20.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = CSVic20.m; sourceTree = "<group>"; };
+		4B886FF41D03B61E004291C3 /* CSVic20.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = CSVic20.mm; sourceTree = "<group>"; };
 		4B92EAC91B7C112B00246143 /* TimingTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TimingTests.swift; sourceTree = "<group>"; };
 		4BAE587D1C447B7A005B9AF0 /* KeyCodes.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = KeyCodes.h; sourceTree = "<group>"; };
 		4BB297DF1B587D8200A49093 /* Clock SignalTests-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "Clock SignalTests-Bridging-Header.h"; sourceTree = "<group>"; };
@@ -804,7 +804,7 @@
 				4B55CE4D1C3B3BDA0093A61B /* CSMachine.mm */,
 				4B55CE4F1C3B78A80093A61B /* CSMachine+Subclassing.h */,
 				4B886FF31D03B61E004291C3 /* CSVic20.h */,
-				4B886FF41D03B61E004291C3 /* CSVic20.m */,
+				4B886FF41D03B61E004291C3 /* CSVic20.mm */,
 				4BAE587D1C447B7A005B9AF0 /* KeyCodes.h */,
 			);
 			path = Wrappers;
@@ -1698,7 +1698,7 @@
 				4B55CE581C3B7D360093A61B /* Atari2600Document.swift in Sources */,
 				4B0EBFB81C487F2F00A11F35 /* AudioQueue.m in Sources */,
 				4BBB14311CD2CECE00BDB55C /* IntermediateShader.cpp in Sources */,
-				4B886FF51D03B61E004291C3 /* CSVic20.m in Sources */,
+				4B886FF51D03B61E004291C3 /* CSVic20.mm in Sources */,
 				4B73C71A1D036BD90074D992 /* Vic20Document.swift in Sources */,
 				4BBF99181C8FBA6F0075DAFB /* TextureTarget.cpp in Sources */,
 				4BC76E691C98E31700E6EF73 /* FIRFilter.cpp in Sources */,

OSBindings/Mac/Clock Signal/Wrappers/CSVic20.mm

@@ -8,6 +8,14 @@
 
 #import "CSVic20.h"
 
-@implementation CSVic20
+#import "Vic20.hpp"
+
+@implementation CSVic20 {
+	Vic20::Machine _vic20;
+}
+
+- (CRTMachine::Machine * const)machine {
+	return &_vic20;
+}
 
 @end