diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index f340bb52b..a7ea419a9 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -7,6 +7,8 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		4B049CDD1DA3C82F00322067 /* BCDTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B049CDC1DA3C82F00322067 /* BCDTest.swift */; };
+		4B049CDF1DA3C85B00322067 /* BCDTEST_beeb in Resources */ = {isa = PBXBuildFile; fileRef = 4B049CDE1DA3C85B00322067 /* BCDTEST_beeb */; };
 		4B0BE4281D3481E700D5256B /* DigitalPhaseLockedLoop.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B0BE4261D3481E700D5256B /* DigitalPhaseLockedLoop.cpp */; };
 		4B0CCC451C62D0B3001CAC5F /* CRT.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B0CCC421C62D0B3001CAC5F /* CRT.cpp */; };
 		4B14145B1B58879D00E04248 /* CPU6502.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B1414571B58879D00E04248 /* CPU6502.cpp */; };
@@ -389,6 +391,8 @@
 
 /* Begin PBXFileReference section */
 		4B046DC31CFE651500E9E45E /* CRTMachine.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = CRTMachine.hpp; sourceTree = "<group>"; };
+		4B049CDC1DA3C82F00322067 /* BCDTest.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = BCDTest.swift; sourceTree = "<group>"; };
+		4B049CDE1DA3C85B00322067 /* BCDTEST_beeb */ = {isa = PBXFileReference; lastKnownFileType = file; path = BCDTEST_beeb; sourceTree = "<group>"; };
 		4B0B6E121C9DBD5D00FFB60D /* CRTConstants.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = CRTConstants.hpp; sourceTree = "<group>"; };
 		4B0BE4261D3481E700D5256B /* DigitalPhaseLockedLoop.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = DigitalPhaseLockedLoop.cpp; sourceTree = "<group>"; };
 		4B0BE4271D3481E700D5256B /* DigitalPhaseLockedLoop.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = DigitalPhaseLockedLoop.hpp; sourceTree = "<group>"; };
@@ -898,6 +902,7 @@
 		4B1414631B588A1100E04248 /* Test Binaries */ = {
 			isa = PBXGroup;
 			children = (
+				4B049CDE1DA3C85B00322067 /* BCDTEST_beeb */,
 				4BB297E01B587D8300A49093 /* 6502_functional_test.bin */,
 				4BB297E11B587D8300A49093 /* AllSuiteA.bin */,
 				4BB297E41B587D8300A49093 /* Wolfgang Lorenz 6502 test suite */,
@@ -1522,6 +1527,7 @@
 				4BC751B11D157E61006C31D9 /* 6522Tests.swift */,
 				4B1E85801D176468001EF87D /* 6532Tests.swift */,
 				4BB73EB61B587A5100552FC2 /* AllSuiteATests.swift */,
+				4B049CDC1DA3C82F00322067 /* BCDTest.swift */,
 				4B3BA0C21D318AEB005DD7A7 /* C1540Tests.swift */,
 				4BEF6AAB1D35D1C400E73575 /* DPLLTests.swift */,
 				4B1414611B58888700E04248 /* KlausDormannTests.swift */,
@@ -1930,6 +1936,7 @@
 				4BB299641B587D8400A49093 /* insiy in Resources */,
 				4BB299E61B587D8400A49093 /* trap10 in Resources */,
 				4BB299651B587D8400A49093 /* insz in Resources */,
+				4B049CDF1DA3C85B00322067 /* BCDTEST_beeb in Resources */,
 				4BB299161B587D8400A49093 /* bccr in Resources */,
 				4BB299211B587D8400A49093 /* bvsr in Resources */,
 				4BB2991F1B587D8400A49093 /* brkn in Resources */,
@@ -2227,6 +2234,7 @@
 				4B3BA0C31D318AEC005DD7A7 /* C1540Tests.swift in Sources */,
 				4B1414621B58888700E04248 /* KlausDormannTests.swift in Sources */,
 				4B1414601B58885000E04248 /* WolfgangLorenzTests.swift in Sources */,
+				4B049CDD1DA3C82F00322067 /* BCDTest.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
diff --git a/OSBindings/Mac/Clock SignalTests/BCDTEST_beeb b/OSBindings/Mac/Clock SignalTests/BCDTEST_beeb
new file mode 100755
index 000000000..77ec9e296
Binary files /dev/null and b/OSBindings/Mac/Clock SignalTests/BCDTEST_beeb differ
diff --git a/OSBindings/Mac/Clock SignalTests/BCDTest.swift b/OSBindings/Mac/Clock SignalTests/BCDTest.swift
new file mode 100644
index 000000000..5a4945fad
--- /dev/null
+++ b/OSBindings/Mac/Clock SignalTests/BCDTest.swift	
@@ -0,0 +1,58 @@
+//
+//  BCDTest.swift
+//  Clock Signal
+//
+//  Created by Thomas Harte on 04/10/2016.
+//  Copyright © 2016 Thomas Harte. All rights reserved.
+//
+
+import Foundation
+import XCTest
+
+class BCDTest: XCTestCase, CSTestMachineJamHandler {
+
+	func testBCD() {
+		if let filename = Bundle(for: type(of: self)).path(forResource: "BCDTEST_beeb", ofType: nil) {
+			if let bcdTest = try? Data(contentsOf: URL(fileURLWithPath: filename)) {
+				let machine = CSTestMachine()
+				machine.jamHandler = self
+
+				machine.setData(bcdTest, atAddress: 0x2900)
+
+				// install a launchpad
+				machine.setValue(0x20, forAddress:0x200)	// JSR 0x2900
+				machine.setValue(0x00, forAddress:0x201)
+				machine.setValue(0x29, forAddress:0x202)
+				machine.setValue(0x4c, forAddress:0x203)	// JMP 0x0203
+				machine.setValue(0x03, forAddress:0x204)
+				machine.setValue(0x02, forAddress:0x205)
+
+				machine.setValue(0x200, for: CSTestMachineRegister.programCounter)
+
+				machine.setValue(CSTestMachineJamOpcode, forAddress:0xffee)	// OSWRCH
+				machine.setValue(CSTestMachineJamOpcode, forAddress:0xffff)	// end of test
+
+				while(machine.value(for: .programCounter) != 0x203) {
+					machine.runForNumber(ofCycles: 1000)
+				}
+				XCTAssert(machine.value(forAddress:0x84) == 0, output)
+			}
+		}
+	}
+
+	fileprivate var output: String = ""
+	func testMachine(_ machine: CSTestMachine!, didJamAtAddress address: UInt16) {
+
+		switch address {
+			case 0xffee:
+				let character = machine.value(for: CSTestMachineRegister.A)
+				output.append(Character(UnicodeScalar(character)!))
+
+				machine.returnFromSubroutine()
+
+			default:
+				let hexAddress = String(format:"%04x", address)
+				NSException(name: NSExceptionName(rawValue: "Failed Test"), reason: "Processor jammed unexpectedly at \(hexAddress)", userInfo: nil).raise()
+		}
+	}
+}
diff --git a/OSBindings/Mac/Clock SignalTests/WolfgangLorenzTests.swift b/OSBindings/Mac/Clock SignalTests/WolfgangLorenzTests.swift
index e30dae422..c98236820 100644
--- a/OSBindings/Mac/Clock SignalTests/WolfgangLorenzTests.swift	
+++ b/OSBindings/Mac/Clock SignalTests/WolfgangLorenzTests.swift	
@@ -226,11 +226,11 @@ class WolfgangLorenzTests: XCTestCase, CSTestMachineJamHandler {
 				] as [UInt8]), count: 19)
 				machine.setData( irqHandler, atAddress: 0xff48)
 
-				machine.setValue(CSTestMachineJamOpcode, forAddress:0xffd2);  // print character
-				machine.setValue(CSTestMachineJamOpcode, forAddress:0xe16f);  // load
-				machine.setValue(CSTestMachineJamOpcode, forAddress:0xffe4);  // scan keyboard
-				machine.setValue(CSTestMachineJamOpcode, forAddress:0x8000);  // exit
-				machine.setValue(CSTestMachineJamOpcode, forAddress:0xa474);  // exit
+				machine.setValue(CSTestMachineJamOpcode, forAddress:0xffd2)	// print character
+				machine.setValue(CSTestMachineJamOpcode, forAddress:0xe16f)	// load
+				machine.setValue(CSTestMachineJamOpcode, forAddress:0xffe4)	// scan keyboard
+				machine.setValue(CSTestMachineJamOpcode, forAddress:0x8000)	// exit
+				machine.setValue(CSTestMachineJamOpcode, forAddress:0xa474)	// exit
 
 				machine.setValue(0x0801, for: CSTestMachineRegister.programCounter)
 				machine.setValue(0xfd, for: CSTestMachineRegister.stackPointer)