diff --git a/Machines/ZX8081/ZX8081.cpp b/Machines/ZX8081/ZX8081.cpp
index 4af76c948..184434791 100644
--- a/Machines/ZX8081/ZX8081.cpp
+++ b/Machines/ZX8081/ZX8081.cpp
@@ -36,9 +36,6 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
 		set_hsync(true);
 		if(nmi_is_enabled_) {
 			set_non_maskable_interrupt_line(true);
-			if(!get_halt_line()) {
-				set_wait_line(true);
-			}
 		}
 		video_->run_for_cycles(horizontal_counter_ - vsync_start_cycle_);
 	} else if(previous_counter < vsync_end_cycle_ && horizontal_counter_ >= vsync_end_cycle_) {
@@ -56,6 +53,10 @@ int Machine::perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
 	if(is_zx81_) horizontal_counter_ %= 207;
 	tape_player_.run_for_cycles(cycle.length);
 
+	if(nmi_is_enabled_ && !get_halt_line() && get_non_maskable_interrupt_line()) {
+		set_wait_line(true);
+	}
+
 	if(!cycle.is_terminal()) {
 		return 0;
 	}
diff --git a/Processors/Z80/Z80.hpp b/Processors/Z80/Z80.hpp
index 20622b965..ce9c9bb46 100644
--- a/Processors/Z80/Z80.hpp
+++ b/Processors/Z80/Z80.hpp
@@ -76,14 +76,16 @@ struct PartialMachineCycle {
 		Internal,
 		BusAcknowledge,
 
-		ReadStart,
 		ReadWait,
-		WriteStart,
 		WriteWait,
-		InputStart,
 		InputWait,
+		OutputWait,
+		InterruptWait,
+
+		ReadStart,
+		WriteStart,
+		InputStart,
 		OutputStart,
-		OutputWait
 	} operation;
 	int length;
 	uint16_t *address;
@@ -96,6 +98,9 @@ struct PartialMachineCycle {
 	inline bool is_terminal() const {
 		return operation <= Operation::BusAcknowledge;
 	}
+	inline bool is_wait() const {
+		return operation >= Operation::ReadWait && operation <= Operation::InterruptWait;
+	}
 };
 
 // Elemental bus operations
@@ -115,11 +120,12 @@ struct PartialMachineCycle {
 #define InputWait(addr, val, f)		{PartialMachineCycle::InputWait, 1, &addr.full, &val, f}
 #define InputEnd(addr, val)			{PartialMachineCycle::Input, 1, &addr.full, &val, false}
 
-#define OutputStart(addr, val)		{PartialMachineCycle::OutputStart, 2, &addr.full, &val}
+#define OutputStart(addr, val)		{PartialMachineCycle::OutputStart, 2, &addr.full, &val, false}
 #define OutputWait(addr, val, f)	{PartialMachineCycle::OutputWait, 1, &addr.full, &val, f}
-#define OutputEnd(addr, val)		{PartialMachineCycle::Output, 1, &addr.full, &val}
+#define OutputEnd(addr, val)		{PartialMachineCycle::Output, 1, &addr.full, &val, false}
 
-#define IntAck(length, val)			{PartialMachineCycle::Interrupt, length, nullptr, &val}
+#define IntAck(length, val)			{PartialMachineCycle::Interrupt, length, nullptr, &val, false}
+#define IntWait(val)				{PartialMachineCycle::InterruptWait, 1, nullptr, &val, true}
 
 // A wrapper to express a bus operation as a micro-op
 #define BusOp(op)					{MicroOp::BusOperation, nullptr, nullptr, op}
@@ -134,7 +140,7 @@ struct PartialMachineCycle {
 
 #define Input(addr, val)			BusOp(InputStart(addr, val)), BusOp(InputWait(addr, val, false)), BusOp(InputWait(addr, val, true)), BusOp(InputEnd(addr, val))
 #define Output(addr, val)			BusOp(OutputStart(addr, val)), BusOp(OutputWait(addr, val, false)), BusOp(OutputWait(addr, val, true)), BusOp(OutputEnd(addr, val))
-#define InternalOperation(len)		{MicroOp::BusOperation, nullptr, nullptr, {PartialMachineCycle::Internal, len}}
+#define InternalOperation(len)		{MicroOp::BusOperation, nullptr, nullptr, {PartialMachineCycle::Internal, len, nullptr, nullptr, false}}
 
 /// A sequence is a series of micro-ops that ends in a move-to-next-program operation.
 #define Sequence(...)				{ __VA_ARGS__, {MicroOp::MoveToNextProgram} }
@@ -186,7 +192,7 @@ template <class T> class Processor {
 		};
 		uint8_t request_status_;
 		uint8_t last_request_status_;
-		bool irq_line_;
+		bool irq_line_, nmi_line_;
 		bool bus_request_line_;
 		bool wait_line_;
 
@@ -765,6 +771,7 @@ template <class T> class Processor {
 			request_status_(Interrupt::PowerOn),
 			last_request_status_(Interrupt::PowerOn),
 			irq_line_(false),
+			nmi_line_(false),
 			bus_request_line_(false),
 			pc_increment_(1),
 			scheduled_program_counter_(nullptr) {
@@ -800,6 +807,7 @@ template <class T> class Processor {
 				{ MicroOp::BeginNMI },
 				BusOp(ReadOpcodeStart()),
 				BusOp(ReadOpcodeWait(1, false)),
+				BusOp(ReadOpcodeWait(1, true)),
 				BusOp(Refresh(2)),
 				Push(pc_),
 				{ MicroOp::JumpTo66, nullptr, nullptr},
@@ -808,11 +816,13 @@ template <class T> class Processor {
 			MicroOp irq_mode0_program[] = {
 				{ MicroOp::BeginIRQMode0 },
 				BusOp(IntAck(4, operation_)),
+				BusOp(IntWait(operation_)),
 				{ MicroOp::DecodeOperationNoRChange }
 			};
 			MicroOp irq_mode1_program[] = {
 				{ MicroOp::BeginIRQ },
 				BusOp(IntAck(5, operation_)),
+				BusOp(IntWait(operation_)),
 				BusOp(Refresh(2)),
 				Push(pc_),
 				{ MicroOp::Move16, &temp16_.full, &pc_.full },
@@ -821,6 +831,7 @@ template <class T> class Processor {
 			MicroOp irq_mode2_program[] = {
 				{ MicroOp::BeginIRQ },
 				BusOp(IntAck(5, temp16_.bytes.low)),
+				BusOp(IntWait(temp16_.bytes.low)),
 				BusOp(Refresh(2)),
 				Push(pc_),
 				{ MicroOp::Move8, &ir_.bytes.high, &temp16_.bytes.high },
@@ -872,7 +883,7 @@ template <class T> class Processor {
 			while(1) {
 
 				while(bus_request_line_) {
-					static PartialMachineCycle bus_acknowledge_cycle = {PartialMachineCycle::BusAcknowledge, 1};
+					static PartialMachineCycle bus_acknowledge_cycle = {PartialMachineCycle::BusAcknowledge, 1, nullptr, nullptr, false};
 					number_of_cycles_ -= static_cast<T *>(this)->perform_machine_cycle(bus_acknowledge_cycle) + 1;
 					if(!number_of_cycles_) {
 						static_cast<T *>(this)->flush();
@@ -1878,6 +1889,10 @@ template <class T> class Processor {
 			}
 		}
 
+		bool get_interrupt_line() {
+			return irq_line_;
+		}
+
 		/*!
 			Sets the logical value of the non-maskable interrupt line.
 			
@@ -1885,6 +1900,7 @@ template <class T> class Processor {
 		*/
 		void set_non_maskable_interrupt_line(bool value, int offset = 0) {
 			// NMIs are edge triggered and cannot be masked.
+			nmi_line_ = value;
 			if(value) {
 				request_status_ |= Interrupt::NMI;
 				if(offset < 0) {
@@ -1893,6 +1909,10 @@ template <class T> class Processor {
 			}
 		}
 
+		bool get_non_maskable_interrupt_line() {
+			return nmi_line_;
+		}
+
 		/*!
 			Sets the logical value of the bus request line.
 		*/
@@ -1900,6 +1920,10 @@ template <class T> class Processor {
 			bus_request_line_ = value;
 		}
 
+		bool get_bus_request_line() {
+			return bus_request_line_;
+		}
+
 		/*!
 			Sets the logical value of the reset line.
 		*/
@@ -1925,6 +1949,10 @@ template <class T> class Processor {
 			wait_line_ = value;
 		}
 
+		bool get_wait_line() {
+			return wait_line_;
+		}
+
 		/*!
 			For receivers of perform_machine_cycle only. Temporarily rejects the current machine
 			cycle, causing time to be rewinded to its beginning.