diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index 057575c69..1571aec89 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -313,6 +313,8 @@
 		4BBF99181C8FBA6F0075DAFB /* TextureTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BBF99121C8FBA6F0075DAFB /* TextureTarget.cpp */; };
 		4BC3B74F1CD194CC00F86E85 /* Shader.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BC3B74D1CD194CC00F86E85 /* Shader.cpp */; };
 		4BC3B7521CD1956900F86E85 /* OutputShader.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BC3B7501CD1956900F86E85 /* OutputShader.cpp */; };
+		4BC751B21D157E61006C31D9 /* 6522Tests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BC751B11D157E61006C31D9 /* 6522Tests.swift */; };
+		4BC751B61D157EB3006C31D9 /* MOS6522Bridge.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4BC751B51D157EB3006C31D9 /* MOS6522Bridge.mm */; };
 		4BC76E691C98E31700E6EF73 /* FIRFilter.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BC76E671C98E31700E6EF73 /* FIRFilter.cpp */; };
 		4BC76E6B1C98F43700E6EF73 /* Accelerate.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 4BC76E6A1C98F43700E6EF73 /* Accelerate.framework */; };
 		4BC9DF451D044FCA00F44158 /* ROMImages in Resources */ = {isa = PBXBuildFile; fileRef = 4BC9DF441D044FCA00F44158 /* ROMImages */; };
@@ -685,6 +687,9 @@
 		4BC3B74E1CD194CC00F86E85 /* Shader.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = Shader.hpp; sourceTree = "<group>"; };
 		4BC3B7501CD1956900F86E85 /* OutputShader.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = OutputShader.cpp; sourceTree = "<group>"; };
 		4BC3B7511CD1956900F86E85 /* OutputShader.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = OutputShader.hpp; sourceTree = "<group>"; };
+		4BC751B11D157E61006C31D9 /* 6522Tests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = 6522Tests.swift; sourceTree = "<group>"; };
+		4BC751B41D157EB3006C31D9 /* MOS6522Bridge.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MOS6522Bridge.h; sourceTree = "<group>"; };
+		4BC751B51D157EB3006C31D9 /* MOS6522Bridge.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = MOS6522Bridge.mm; sourceTree = "<group>"; };
 		4BC76E671C98E31700E6EF73 /* FIRFilter.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = FIRFilter.cpp; sourceTree = "<group>"; };
 		4BC76E681C98E31700E6EF73 /* FIRFilter.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = FIRFilter.hpp; sourceTree = "<group>"; };
 		4BC76E6A1C98F43700E6EF73 /* Accelerate.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = Accelerate.framework; path = System/Library/Frameworks/Accelerate.framework; sourceTree = SDKROOT; };
@@ -1214,15 +1219,18 @@
 		4BB73EB51B587A5100552FC2 /* Clock SignalTests */ = {
 			isa = PBXGroup;
 			children = (
-				4BB73EB81B587A5100552FC2 /* Info.plist */,
 				4BB297DF1B587D8200A49093 /* Clock SignalTests-Bridging-Header.h */,
-				4B1414631B588A1100E04248 /* Test Binaries */,
+				4BC751B41D157EB3006C31D9 /* MOS6522Bridge.h */,
 				4BB297E21B587D8300A49093 /* TestMachine.h */,
+				4BC751B51D157EB3006C31D9 /* MOS6522Bridge.mm */,
 				4BB297E31B587D8300A49093 /* TestMachine.mm */,
+				4BB73EB81B587A5100552FC2 /* Info.plist */,
+				4BC751B11D157E61006C31D9 /* 6522Tests.swift */,
 				4BB73EB61B587A5100552FC2 /* AllSuiteATests.swift */,
 				4B1414611B58888700E04248 /* KlausDormannTests.swift */,
-				4B14145F1B58885000E04248 /* WolfgangLorenzTests.swift */,
 				4B92EAC91B7C112B00246143 /* TimingTests.swift */,
+				4B14145F1B58885000E04248 /* WolfgangLorenzTests.swift */,
+				4B1414631B588A1100E04248 /* Test Binaries */,
 			);
 			path = "Clock SignalTests";
 			sourceTree = "<group>";
@@ -1774,10 +1782,12 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				4BC751B61D157EB3006C31D9 /* MOS6522Bridge.mm in Sources */,
 				4B14145E1B5887AA00E04248 /* CPU6502AllRAM.cpp in Sources */,
 				4B14145D1B5887A600E04248 /* CPU6502.cpp in Sources */,
 				4B92EACA1B7C112B00246143 /* TimingTests.swift in Sources */,
 				4BB73EB71B587A5100552FC2 /* AllSuiteATests.swift in Sources */,
+				4BC751B21D157E61006C31D9 /* 6522Tests.swift in Sources */,
 				4B1414621B58888700E04248 /* KlausDormannTests.swift in Sources */,
 				4BB298F01B587D8400A49093 /* TestMachine.mm in Sources */,
 				4B1414601B58885000E04248 /* WolfgangLorenzTests.swift in Sources */,
diff --git a/OSBindings/Mac/Clock SignalTests/6522Tests.swift b/OSBindings/Mac/Clock SignalTests/6522Tests.swift
new file mode 100644
index 000000000..833d17621
--- /dev/null
+++ b/OSBindings/Mac/Clock SignalTests/6522Tests.swift	
@@ -0,0 +1,13 @@
+//
+//  6522Tests.swift
+//  Clock Signal
+//
+//  Created by Thomas Harte on 18/06/2016.
+//  Copyright © 2016 Thomas Harte. All rights reserved.
+//
+
+import XCTest
+import Foundation
+
+class MOS6522Tests: XCTestCase {
+}
diff --git a/OSBindings/Mac/Clock SignalTests/Clock SignalTests-Bridging-Header.h b/OSBindings/Mac/Clock SignalTests/Clock SignalTests-Bridging-Header.h
index a628ea2a9..0bcb4a76b 100644
--- a/OSBindings/Mac/Clock SignalTests/Clock SignalTests-Bridging-Header.h	
+++ b/OSBindings/Mac/Clock SignalTests/Clock SignalTests-Bridging-Header.h	
@@ -3,3 +3,4 @@
 //
 
 #import "TestMachine.h"
+#import "MOS6522Bridge.h"
diff --git a/OSBindings/Mac/Clock SignalTests/MOS6522Bridge.h b/OSBindings/Mac/Clock SignalTests/MOS6522Bridge.h
new file mode 100644
index 000000000..d2bed3fe8
--- /dev/null
+++ b/OSBindings/Mac/Clock SignalTests/MOS6522Bridge.h	
@@ -0,0 +1,20 @@
+//
+//  MOS6522Bridge.h
+//  Clock Signal
+//
+//  Created by Thomas Harte on 18/06/2016.
+//  Copyright © 2016 Thomas Harte. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+@interface MOS6522Bridge : NSObject
+
+@property (nonatomic, readonly) BOOL irqLine;
+
+- (void)setValue:(uint8_t)value forRegister:(NSUInteger)registerNumber;
+- (uint8_t)valueForRegister:(NSUInteger)registerNumber;
+
+- (void)runForHalfCycles:(NSUInteger)numberOfHalfCycles;
+
+@end
diff --git a/OSBindings/Mac/Clock SignalTests/MOS6522Bridge.mm b/OSBindings/Mac/Clock SignalTests/MOS6522Bridge.mm
new file mode 100644
index 000000000..0f1a725ed
--- /dev/null
+++ b/OSBindings/Mac/Clock SignalTests/MOS6522Bridge.mm	
@@ -0,0 +1,55 @@
+//
+//  MOS6522Bridge.m
+//  Clock Signal
+//
+//  Created by Thomas Harte on 18/06/2016.
+//  Copyright © 2016 Thomas Harte. All rights reserved.
+//
+
+#import "MOS6522Bridge.h"
+#include "6522.hpp"
+
+@class MOS6522Bridge;
+
+class VanillaVIA: public MOS::MOS6522<VanillaVIA> {
+	public:
+		MOS6522Bridge *bridge;
+		bool irq_line;
+
+		void set_interrupt_status(bool new_status)
+		{
+			irq_line = new_status;
+		}
+};
+
+@implementation MOS6522Bridge
+{
+	VanillaVIA _via;
+}
+
+- (instancetype)init
+{
+	self = [super init];
+	if(self)
+	{
+		_via.bridge = self;
+	}
+	return self;
+}
+
+- (void)setValue:(uint8_t)value forRegister:(NSUInteger)registerNumber
+{
+	_via.set_register((int)registerNumber, value);
+}
+
+- (uint8_t)valueForRegister:(NSUInteger)registerNumber
+{
+	return _via.get_register((int)registerNumber);
+}
+
+- (void)runForHalfCycles:(NSUInteger)numberOfHalfCycles
+{
+	_via.run_for_cycles(numberOfHalfCycles);
+}
+
+@end
diff --git a/Processors/6502/CPU6502.hpp b/Processors/6502/CPU6502.hpp
index e4e884a06..e335df436 100644
--- a/Processors/6502/CPU6502.hpp
+++ b/Processors/6502/CPU6502.hpp
@@ -1057,6 +1057,13 @@ template <class T> class Processor {
 			static_cast<T *>(this)->synchronise();
 		}
 
+		/*!
+			Called to announce the end of a run_for_cycles period, allowing deferred work to take place.
+
+			Users of the 6502 template may override this.
+		*/
+		void synchronise() {}
+
 		/*!
 			Gets the value of a register.