Plumbed through to allow interrupt tests, wrote an NMI test, corrected the error revealed.

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

@@ -8,6 +8,7 @@
 
 /* Begin PBXBuildFile section */
 		4B049CDD1DA3C82F00322067 /* BCDTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B049CDC1DA3C82F00322067 /* BCDTest.swift */; };
+		4B08A2751EE35D56008B7065 /* Z80InterruptTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B08A2741EE35D56008B7065 /* Z80InterruptTests.swift */; };
 		4B0BE4281D3481E700D5256B /* DigitalPhaseLockedLoop.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B0BE4261D3481E700D5256B /* DigitalPhaseLockedLoop.cpp */; };
 		4B0CCC451C62D0B3001CAC5F /* CRT.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B0CCC421C62D0B3001CAC5F /* CRT.cpp */; };
 		4B121F951E05E66800BFDA12 /* PCMPatchedTrackTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4B121F941E05E66800BFDA12 /* PCMPatchedTrackTests.mm */; };
@@ -442,6 +443,7 @@
 /* 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>"; };
+		4B08A2741EE35D56008B7065 /* Z80InterruptTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Z80InterruptTests.swift; 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>"; };
@@ -1795,6 +1797,7 @@
 				4BBF49AE1ED2880200AB3669 /* FUSETests.swift */,
 				4B1414611B58888700E04248 /* KlausDormannTests.swift */,
 				4B14145F1B58885000E04248 /* WolfgangLorenzTests.swift */,
+				4B08A2741EE35D56008B7065 /* Z80InterruptTests.swift */,
 				4BFCA12A1ECBE7C400AC40C1 /* ZexallTests.swift */,
 				4B3BA0C41D318B44005DD7A7 /* Bridges */,
 				4B1414631B588A1100E04248 /* Test Binaries */,
@@ -2599,6 +2602,7 @@
 				4BC9E1EE1D23449A003FCEE4 /* 6502InterruptTests.swift in Sources */,
 				4BEF6AAA1D35CE9E00E73575 /* DigitalPhaseLockedLoopBridge.mm in Sources */,
 				4B924E991E74D22700B76AF1 /* AtariStaticAnalyserTests.mm in Sources */,
+				4B08A2751EE35D56008B7065 /* Z80InterruptTests.swift in Sources */,
 				4BFCA1241ECBDCB400AC40C1 /* AllRAMProcessor.cpp in Sources */,
 				4B50730A1DDFCFDF00C48FBD /* ArrayBuilderTests.mm in Sources */,
 				4BBF49AF1ED2880200AB3669 /* FUSETests.swift in Sources */,

OSBindings/Mac/Clock SignalTests/Bridges/TestMachineZ80.h

@@ -66,4 +66,7 @@ typedef NS_ENUM(NSInteger, CSTestMachineZ80Register) {
 
 @property(nonatomic, readonly) BOOL isHalted;
 
+@property(nonatomic) BOOL nmiLine;
+@property(nonatomic) BOOL irqLine;
+
 @end

OSBindings/Mac/Clock SignalTests/Bridges/TestMachineZ80.mm

@@ -173,6 +173,16 @@ static CPU::Z80::Register registerForRegister(CSTestMachineZ80Register reg) {
 	return _processor->get_halt_line() ? YES : NO;
 }
 
+- (void)setNmiLine:(BOOL)nmiLine {
+	_nmiLine = nmiLine;
+	_processor->set_non_maskable_interrupt_line(nmiLine ? true : false);
+}
+
+- (void)setIrqLine:(BOOL)irqLine {
+	_irqLine = irqLine;
+	_processor->set_interrupt_line(irqLine ? true : false);
+}
+
 #pragma mark - Z80-specific Runner
 
 - (void)runToNextInstruction {

OSBindings/Mac/Clock SignalTests/Z80InterruptTests.swift

@@ -0,0 +1,45 @@
+//
+//  Z80InterruptTests.swift
+//  Clock Signal
+//
+//  Created by Thomas Harte on 03/06/2017.
+//  Copyright © 2017 Thomas Harte. All rights reserved.
+//
+
+import XCTest
+
+class Z80InterruptTests: XCTestCase {
+
+	func testNMI() {
+		let machine = CSTestMachineZ80()
+
+		// start the PC at 0x0100 and install two NOPs for it
+		machine.setValue(0x0100, for: .programCounter)
+		machine.setValue(0, for: .IFF1)
+		machine.setValue(1, for: .IFF2)
+		machine.setValue(0x00, atAddress: 0x0100)
+		machine.setValue(0x00, atAddress: 0x0101)
+
+		// put the stack at the top of memory
+		machine.setValue(0, for: .stackPointer)
+
+		// run for four cycles, and signal an NMI
+		machine.runForNumber(ofCycles: 4)
+		machine.nmiLine = true
+
+		// run for four more cycles to get to where the NMI should be recognised
+		machine.runForNumber(ofCycles: 4)
+		XCTAssertEqual(machine.value(for: .programCounter), 0x0102)
+
+		// run for eleven more cycles to allow the NMI to begin
+		machine.runForNumber(ofCycles: 11)
+
+		// confirm that the PC is now at 0x66, that the old is on the stack and
+		// that IFF1 has migrated to IFF2
+		XCTAssertEqual(machine.value(for: .programCounter), 0x66)
+		XCTAssertEqual(machine.value(atAddress: 0xffff), 0x01)
+		XCTAssertEqual(machine.value(atAddress: 0xfffe), 0x02)
+		XCTAssertEqual(machine.value(for: .IFF2), 0)
+	}
+
+}

Processors/Z80/Z80.hpp

@@ -136,6 +136,7 @@ struct MicroOp {
 		BeginIRQ,
 		BeginIRQMode0,
 		RETN,
+		JumpTo66,
 		HALT,
 
 		DJNZ,
@@ -701,6 +702,7 @@ template <class T> class Processor: public MicroOpScheduler<MicroOp> {
 				{ MicroOp::BeginNMI },
 				{ MicroOp::BusOperation, nullptr, nullptr, {ReadOpcode, 5, &pc_.full, &operation_}},
 				PUSH(pc_),
+				{ MicroOp::JumpTo66, nullptr, nullptr},
 				{ MicroOp::MoveToNextProgram }
 			};
 			MicroOp irq_mode0_program[] = {
@@ -1476,6 +1478,10 @@ template <class T> class Processor: public MicroOpScheduler<MicroOp> {
 						request_status_ &= ~Interrupt::IRQ;
 					break;
 
+					case MicroOp::JumpTo66:
+						pc_.full = 0x66;
+					break;
+
 					case MicroOp::RETN:
 						iff1_ = iff2_;
 						if(irq_line_ && iff1_) request_status_ |= Interrupt::IRQ;

Processors/Z80/Z80AllRAM.cpp

@@ -74,6 +74,14 @@ class ConcreteAllRAMProcessor: public AllRAMProcessor, public Processor<Concrete
 		void reset_power_on() {
 			return CPU::Z80::Processor<ConcreteAllRAMProcessor>::reset_power_on();
 		}
+
+		void set_interrupt_line(bool value) {
+			CPU::Z80::Processor<ConcreteAllRAMProcessor>::set_interrupt_line(value);
+		}
+
+		void set_non_maskable_interrupt_line(bool value) {
+			CPU::Z80::Processor<ConcreteAllRAMProcessor>::set_non_maskable_interrupt_line(value);
+		}
 };
 
 }

Processors/Z80/Z80AllRAM.hpp

@@ -33,6 +33,8 @@ class AllRAMProcessor:
 		virtual void set_value_of_register(Register r, uint16_t value) = 0;
 		virtual bool get_halt_line() = 0;
 		virtual void reset_power_on() = 0;
+		virtual void set_interrupt_line(bool value) = 0;
+		virtual void set_non_maskable_interrupt_line(bool value) = 0;
 
 	protected:
 		MemoryAccessDelegate *delegate_;