Lots of miscellaneous cycle accurate updates

Z80/HarteTest_Z80/TestRunner.cpp

@@ -20,4 +20,4 @@ void TestRunner::lowerPOWER() noexcept {
     EightBit::Bus::lowerPOWER();
 }
 
-void TestRunner::initialise() {}
+void TestRunner::initialise() noexcept {}

Z80/HarteTest_Z80/TestRunner.h

@@ -19,7 +19,7 @@ public:
     void raisePOWER() noexcept final;
     void lowerPOWER() noexcept final;
 
-    void initialise() final;
+    void initialise() noexcept final;
 
     [[nodiscard]] constexpr auto& RAM() noexcept { return m_ram; }
     [[nodiscard]] constexpr auto& ports() noexcept { return m_ports; }

Z80/inc/Disassembler.h

@@ -10,7 +10,7 @@ namespace EightBit {
 
 	class Disassembler final {
 	public:
-		Disassembler(Bus& bus) noexcept;
+		Disassembler(Bus& bus);
 
 		static std::string state(Z80& cpu);
 		std::string disassemble(Z80& cpu);

Z80/inc/Profiler.h

@@ -27,21 +27,21 @@ namespace EightBit {
 		[[nodiscard]] constexpr const auto& instructions() const { return m_instructions; }
 		[[nodiscard]] constexpr const auto& addresses() const { return m_addresses; }
 
-		[[nodiscard]] constexpr auto instructions_available() const noexcept {
+		[[nodiscard]] constexpr auto instructions_available() const {
 			const auto found = std::find_if(
 				instructions().begin(), instructions().end(),
 				[](const auto& value) { return value != 0; });
 			return found != instructions().end();
 		}
 
-		[[nodiscard]] constexpr auto addresses_available() const noexcept {
+		[[nodiscard]] constexpr auto addresses_available() const {
 			const auto found = std::find_if(
 				addresses().begin(), addresses().end(),
 				[](const auto& value) { return value != 0; });
 			return found != addresses().end();
 		}
 
-		[[nodiscard]] constexpr auto available() const noexcept {
+		[[nodiscard]] constexpr auto available() const {
 			return instructions_available() || addresses_available();
 		}
 

Z80/inc/Z80.h

@@ -29,14 +29,6 @@ namespace EightBit {
 		DECLARE_PIN_OUTPUT(RD)
 		DECLARE_PIN_OUTPUT(WR)
 
-	private:
-		DEFINE_PIN_ACTIVATOR_LOW(RFSH)
-		DEFINE_PIN_ACTIVATOR_LOW(M1)
-		DEFINE_PIN_ACTIVATOR_LOW(MREQ)
-		DEFINE_PIN_ACTIVATOR_LOW(IORQ)
-		DEFINE_PIN_ACTIVATOR_LOW(RD)
-		DEFINE_PIN_ACTIVATOR_LOW(WR)
-
 	public:
 		struct refresh_t {
 
@@ -70,30 +62,24 @@ namespace EightBit {
 			CF = Bit0,
 		};
 
-		Z80(Bus& bus, InputOutput& ports);
+		Z80(Bus& bus, InputOutput& ports) noexcept;
 
-		Z80(const Z80& rhs);
-		bool operator==(const Z80& rhs) const;
+		Z80(const Z80& rhs) noexcept;
+		bool operator==(const Z80& rhs) const noexcept;
 
 		void execute() noexcept final;
 		void poweredStep() noexcept final;
 
-		[[nodiscard]] const register16_t& AF() const noexcept final;
-		[[nodiscard]] auto& AF() noexcept { return IntelProcessor::AF(); }
-		[[nodiscard]] const register16_t& BC() const noexcept final;
-		[[nodiscard]] auto& BC() noexcept { return IntelProcessor::BC(); }
-		[[nodiscard]] const register16_t& DE() const noexcept final;
-		[[nodiscard]] auto& DE() noexcept { return IntelProcessor::DE(); }
-		[[nodiscard]] const register16_t& HL() const noexcept final;
-		[[nodiscard]] auto& HL() noexcept { return IntelProcessor::HL(); }
+		[[nodiscard]] register16_t& AF() noexcept final;
+		[[nodiscard]] register16_t& BC() noexcept final;
+		[[nodiscard]] register16_t& DE() noexcept final;
+		[[nodiscard]] register16_t& HL() noexcept final;
 
-		[[nodiscard]] constexpr const auto& IX() const noexcept { return m_ix; }
-		NON_CONST_REGISTOR_ACCESSOR(IX);
+		[[nodiscard]] constexpr auto& IX() noexcept { return m_ix; }
 		[[nodiscard]] constexpr auto& IXH() noexcept { return IX().high; }
 		[[nodiscard]] constexpr auto& IXL() noexcept { return IX().low; }
 
-		[[nodiscard]] constexpr const auto& IY() const noexcept { return m_iy; }
-		NON_CONST_REGISTOR_ACCESSOR(IY);
+		[[nodiscard]] constexpr auto& IY() noexcept { return m_iy; }
 		[[nodiscard]] constexpr auto& IYH() noexcept { return IY().high; }
 		[[nodiscard]] constexpr auto& IYL() noexcept { return IY().low; }
 
@@ -109,16 +95,11 @@ namespace EightBit {
 		// programmer. During refresh, the contents of the I Register are placed on the upper eight
 		// bits of the address bus.
 		[[nodiscard]] constexpr auto& REFRESH() noexcept { return m_refresh; }
-		[[nodiscard]] constexpr auto REFRESH() const noexcept { return m_refresh; }
 
 		[[nodiscard]] constexpr auto& IV() noexcept { return iv; }
-		[[nodiscard]] constexpr auto IV() const noexcept { return iv; }
 		[[nodiscard]] constexpr auto& IM() noexcept { return m_interruptMode; }
-		[[nodiscard]] constexpr auto IM() const noexcept { return m_interruptMode; }
 		[[nodiscard]] constexpr auto& IFF1() noexcept { return m_iff1; }
-		[[nodiscard]] constexpr auto IFF1() const noexcept { return m_iff1; }
 		[[nodiscard]] constexpr auto& IFF2() noexcept { return m_iff2; }
-		[[nodiscard]] constexpr auto IFF2() const noexcept { return m_iff2; }
 
 		[[nodiscard]] constexpr auto& Q() noexcept { return m_q; }
 
@@ -131,18 +112,20 @@ namespace EightBit {
 		[[nodiscard]] constexpr auto requestingRead() const noexcept { return lowered(RD()); }
 		[[nodiscard]] constexpr auto requestingWrite() const noexcept { return lowered(WR()); }
 
+		[[nodiscard]] constexpr auto fetchingOpCode() const noexcept { return lowered(M1()); }
+
 	protected:
 		void handleRESET() noexcept final;
 		void handleINT() noexcept final;
 
-		void memoryUpdate(int ticks) noexcept;
+		void memoryUpdate(int ticks = 1) noexcept;
 		void memoryWrite() noexcept final;
 		uint8_t memoryRead() noexcept final;
 		void refreshMemory() noexcept;
 
 		void jumpRelative(int8_t offset) noexcept final;
 
-		void call(register16_t destination) final;
+		void call(register16_t destination) noexcept final;
 
 	private:
 		bool m_interruptPending = false;
@@ -181,23 +164,17 @@ namespace EightBit {
 
 		void handleNMI() noexcept;
 
-		constexpr void resetPrefixes() noexcept {
-			m_prefixCB = m_prefixDD = m_prefixED = m_prefixFD = false;
-		}
-
 		[[nodiscard]] constexpr auto displaced() const noexcept { return m_prefixDD || m_prefixFD; }
 
 		[[nodiscard]] constexpr void displaceAddress() noexcept {
 			const auto& index_register = m_prefixDD ? IX() : IY();
-			const auto address = index_register.word + m_displacement;
-			MEMPTR().word = address;
-			BUS().ADDRESS() = MEMPTR();
+			BUS().ADDRESS() = MEMPTR() = index_register.word + m_displacement;
 		}
 
 		void fetchDisplacement() noexcept;
 		[[nodiscard]] uint8_t fetchInstruction() noexcept final;
 
-		uint8_t readDataUnderInterrupt();
+		uint8_t readDataUnderInterrupt() noexcept;
 
 		typedef std::function<register16_t(void)> addresser_t;
 		void loadAccumulatorIndirect(addresser_t addresser) noexcept;
@@ -339,70 +316,17 @@ namespace EightBit {
 			return adjustOverflowSub(input, signTest(before), signTest(value), signTest(calculation));
 		}
 
-		[[nodiscard]] bool convertCondition(int flag) noexcept override {
-			switch (flag) {
-			case 0:
-				return zero() == 0;
-			case 1:
-				return zero() != 0;
-			case 2:
-				return carry() == 0;
-			case 3:
-				return carry() != 0;
-			case 4:
-				return parity() == 0;
-			case 5:
-				return parity() != 0;
-			case 6:
-				return sign() == 0;
-			case 7:
-				return sign() != 0;
-			default:
-				UNREACHABLE;
-			}
-		}
-
-		auto subtract(uint8_t value, int carry = 0) noexcept {
-
-			const auto operand = A();
-
-			const register16_t subtraction = operand - value - carry;
-			const auto result = subtraction.low;
-
-			adjustHalfCarrySub(operand, value, result);
-			adjustOverflowSub(operand, value, result);
-
-			setBit(NF);
-			setBit(CF, carryTest(subtraction.high));
-			adjustSZ(result);
-
-			return result;
-		}
+		[[nodiscard]] bool convertCondition(int flag) noexcept final;
 
 		void executeCB(int x, int y, int z) noexcept;
 		void executeED(int x, int y, int z, int p, int q) noexcept;
 		void executeOther(int x, int y, int z, int p, int q) noexcept;
 
-		[[nodiscard]] auto increment(uint8_t operand) noexcept {
-			clearBit(NF);
-			const uint8_t result = operand + 1;
-			adjustSZXY(result);
-			setBit(VF, result == Bit7);
-			clearBit(HC, lowNibble(result));
-			return result;
-		}
+		[[nodiscard]] uint8_t increment(uint8_t operand) noexcept;
+		[[nodiscard]] uint8_t decrement(uint8_t operand) noexcept;
 
-		[[nodiscard]] auto decrement(uint8_t operand) noexcept {
-			setBit(NF);
-			clearBit(HC, lowNibble(operand));
-			const uint8_t result = operand - 1;
-			adjustSZXY(result);
-			setBit(VF, result == Mask7);
-			return result;
-		}
-
-		void disableInterrupts() override;
-		void enableInterrupts() override;
+		void disableInterrupts() noexcept final;
+		void enableInterrupts() noexcept final;
 
 		void retn() noexcept;
 		void reti() noexcept;
@@ -413,178 +337,35 @@ namespace EightBit {
 		void adc(register16_t value) noexcept;
 		void add(register16_t value, int carry = 0) noexcept;
 
-		void add(uint8_t value, int carry = 0) noexcept {
+		void add(uint8_t value, int carry = 0) noexcept;
+		void adc(uint8_t value) noexcept;
+		void sub(uint8_t value, int carry = 0) noexcept;
+		uint8_t subtract(uint8_t value, int carry = 0) noexcept;
+		void sbc(uint8_t value) noexcept;
 
-			const auto operand = A();
+		void andr(uint8_t value) noexcept;
+		void xorr(uint8_t value) noexcept;
+		void orr(uint8_t value) noexcept;
+		void compare(uint8_t value) noexcept;
 
-			intermediate() = operand + value + carry;
-			const auto result = intermediate().low;
+		[[nodiscard]] uint8_t rlc(uint8_t operand) noexcept;
+		[[nodiscard]] uint8_t rrc(uint8_t operand) noexcept;
+		[[nodiscard]] uint8_t rl(uint8_t operand) noexcept;
+		[[nodiscard]] uint8_t rr(uint8_t operand) noexcept;
+		[[nodiscard]] uint8_t sla(uint8_t operand) noexcept;
+		[[nodiscard]] uint8_t sra(uint8_t operand) noexcept;
+		[[nodiscard]] uint8_t sll(uint8_t operand) noexcept;
+		[[nodiscard]] uint8_t srl(uint8_t operand) noexcept;
 
-			adjustHalfCarryAdd(operand, value, result);
-			adjustOverflowAdd(operand, value, result);
-
-			clearBit(NF);
-			setBit(CF, carryTest(intermediate().high));
-			adjustSZXY(result);
-
-			A() = result;
-		}
-
-		void adc(uint8_t value) noexcept {
-			add(value, carry());
-		}
-
-		void sub(uint8_t value, int carry = 0) noexcept {
-			adjustSZXY(A() = subtract(value, carry));
-		}
-
-		void sbc(uint8_t value) noexcept {
-			sub(value, carry());
-		}
-
-		[[nodiscard]] void andr(uint8_t value) noexcept {
-			setBit(HC);
-			clearBit(CF | NF);
-			adjustSZPXY(A() &= value);
-		}
-
-		[[nodiscard]] void xorr(uint8_t value) noexcept {
-			clearBit(HC | CF | NF);
-			adjustSZPXY(A() ^= value);
-		}
-
-		[[nodiscard]] void orr(uint8_t value) noexcept {
-			clearBit(HC | CF | NF);
-			adjustSZPXY(A() |= value);
-		}
-
-		void compare(uint8_t value) noexcept {
-			subtract(value);
-			adjustXY(value);
-		}
-
-		[[nodiscard]] auto rlc(uint8_t operand) noexcept {
-			clearBit(NF | HC);
-			const auto carry = operand & Bit7;
-			setBit(CF, carry);
-			const uint8_t result = (operand << 1) | (carry >> 7);
-			adjustXY(result);
-			return result;
-		}
-
-		[[nodiscard]] auto rrc(uint8_t operand) noexcept {
-			clearBit(NF | HC);
-			const auto carry = operand & Bit0;
-			setBit(CF, carry);
-			const uint8_t result = (operand >> 1) | (carry << 7);
-			adjustXY(result);
-			return result;
-		}
-
-		[[nodiscard]] auto rl(uint8_t operand) noexcept {
-			clearBit(NF | HC);
-			const auto carrying = carry();
-			setBit(CF, operand & Bit7);
-			const uint8_t result = (operand << 1) | carrying;
-			adjustXY(result);
-			return result;
-		}
-
-		[[nodiscard]] auto rr(uint8_t operand) noexcept {
-			clearBit(NF | HC);
-			const auto carrying = carry();
-			setBit(CF, operand & Bit0);
-			const uint8_t result = (operand >> 1) | (carrying << 7);
-			adjustXY(result);
-			return result;
-		}
-
-		[[nodiscard]] auto sla(uint8_t operand) noexcept {
-			clearBit(NF | HC);
-			setBit(CF, operand & Bit7);
-			const uint8_t result = operand << 1;
-			adjustXY(result);
-			return result;
-		}
-
-		[[nodiscard]] auto sra(uint8_t operand) noexcept {
-			clearBit(NF | HC);
-			setBit(CF, operand & Bit0);
-			const uint8_t result = (operand >> 1) | (operand & Bit7);
-			adjustXY(result);
-			return result;
-		}
-
-		[[nodiscard]] auto sll(uint8_t operand) noexcept {
-			clearBit(NF | HC);
-			setBit(CF, operand & Bit7);
-			const uint8_t result = (operand << 1) | Bit0;
-			adjustXY(result);
-			return result;
-		}
-
-		[[nodiscard]] auto srl(uint8_t operand) noexcept {
-			clearBit(NF | HC);
-			setBit(CF, operand & Bit0);
-			const uint8_t result = (operand >> 1) & ~Bit7;
-			adjustXY(result);
-			setBit(ZF, result);
-			return result;
-		}
-
-		void bit(int n, uint8_t operand) noexcept {
-			setBit(HC);
-			clearBit(NF);
-			const auto discarded = operand & Chip::bit(n);
-			adjustSZ(discarded);
-			clearBit(PF, discarded);
-		}
+		void bit(int n, uint8_t operand) noexcept;
 
 		[[nodiscard]] static constexpr auto res(int n, uint8_t operand) noexcept { return Chip::clearBit(operand, Chip::bit(n)); }
 		[[nodiscard]] static constexpr auto set(int n, uint8_t operand) noexcept { return Chip::setBit(operand, Chip::bit(n)); }
 
-		[[nodiscard]] void daa() noexcept {
-
-			auto updated = A();
-
-			const auto lowAdjust = halfCarry() || (lowNibble(A()) > 9);
-			const auto highAdjust = carry() || (A() > 0x99);
-
-			if (subtracting()) {
-				if (lowAdjust)
-					updated -= 6;
-				if (highAdjust)
-					updated -= 0x60;
-			} else {
-				if (lowAdjust)
-					updated += 6;
-				if (highAdjust)
-					updated += 0x60;
-			}
-
-			adjustStatusFlags((F() & (CF | NF) | (A() > 0x99 ? CF : 0) | halfCarryTest(A() ^ updated)));
-			adjustSZPXY(A() = updated);
-		}
-
-		void scf() noexcept {
-			setBit(CF);
-			clearBit(HC | NF);
-			adjustXY((Q() ^ F()) | A());
-		}
-
-		void ccf() noexcept {
-			clearBit(NF);
-			const auto carrying = carry();
-			setBit(HC, carrying);
-			clearBit(CF, carrying);
-			adjustXY(((Q() ^ F()) | A()));
-		}
-
-		void cpl() noexcept final {
-			setBit(HC | NF);
-			IntelProcessor::cpl();
-			adjustXY(A());
-		}
+		void daa() noexcept;
+		void scf() noexcept;
+		void ccf() noexcept;
+		void cpl() noexcept final;
 
 		void xhtl(register16_t& exchange) noexcept;
 
@@ -605,7 +386,7 @@ namespace EightBit {
 		void lddr() noexcept;
 
 		void repeatBlockInstruction() noexcept;
-		void adjustBlockRepeatFlagsIO();
+		void adjustBlockRepeatFlagsIO() noexcept;
 		void adjustBlockInputOutputFlags(int basis) noexcept;
 		void adjustBlockInFlagsIncrement() noexcept;
 		void adjustBlockInFlagsDecrement() noexcept;
@@ -627,21 +408,7 @@ namespace EightBit {
 		void outd() noexcept;
 		void otdr() noexcept;
 
-		void neg() noexcept {
-
-			setBit(PF, A() == Bit7);
-			setBit(CF, A());
-			setBit(NF);
-
-			auto original = A();
-
-			A() = (~A() + 1);	// two's complement
-
-			adjustHalfCarrySub(0U, original, A());
-			adjustOverflowSub(0U, original, A());
-
-			adjustSZXY(A());
-		}
+		void neg() noexcept;
 
 		void rrd(register16_t address, uint8_t& update) noexcept;
 		void rld(register16_t address, uint8_t& update) noexcept;

Z80/src/Disassembler.cpp

@@ -8,7 +8,7 @@
 
 #include "../inc/Z80.h"
 
-EightBit::Disassembler::Disassembler(Bus& bus) noexcept
+EightBit::Disassembler::Disassembler(Bus& bus)
 : m_bus(bus) {
 	// Disable exceptions where too many format arguments are available
 	m_formatter.exceptions(boost::io::all_error_bits ^ boost::io::too_many_args_bit);

Z80/src/Z80.cpp

@@ -3,7 +3,7 @@
 
 // based on http://www.z80.info/decoding.htm
 
-EightBit::Z80::Z80(Bus& bus, InputOutput& ports)
+EightBit::Z80::Z80(Bus& bus, InputOutput& ports) noexcept
 : IntelProcessor(bus),
   m_ports(ports) {
 	RaisedPOWER.connect([this](EventArgs) {
@@ -45,24 +45,19 @@ EightBit::Z80::Z80(Bus& bus, InputOutput& ports)
 	});
 }
 
-EightBit::Z80::Z80(const Z80& rhs)
+EightBit::Z80::Z80(const Z80& rhs) noexcept
 : IntelProcessor(rhs),
-  m_ports(rhs.m_ports) {
-
-	m_registers = rhs.m_registers;
-	m_registerSet = rhs.m_registerSet;
-
-	m_accumulatorFlags = rhs.m_accumulatorFlags;
-	m_accumulatorFlagsSet = rhs.m_accumulatorFlagsSet;
-
-	m_ix = rhs.m_ix;
-	m_iy = rhs.m_iy;
-
-	iv = rhs.iv;
-	m_interruptMode = rhs.m_interruptMode;
-	m_iff1 = rhs.m_iff1;
-	m_iff2 = rhs.m_iff2;
-
+  m_ports(rhs.m_ports),
+  m_registers(rhs.m_registers),
+  m_registerSet(rhs.m_registerSet),
+  m_accumulatorFlags(rhs.m_accumulatorFlags),
+  m_accumulatorFlagsSet(rhs.m_accumulatorFlagsSet),
+  m_ix(rhs.m_ix),
+  m_iy(rhs.m_iy),
+  iv(rhs.iv),
+  m_interruptMode(rhs.m_interruptMode),
+  m_iff1(rhs.m_iff1),
+  m_iff2(rhs.m_iff2) {
 	RFSH() = rhs.RFSH();
 	NMI() = rhs.NMI();
 	M1() = rhs.M1();
@@ -72,47 +67,47 @@ EightBit::Z80::Z80(const Z80& rhs)
 	WR() = rhs.WR();
 }
 
-bool EightBit::Z80::operator==(const EightBit::Z80& rhs) const {
+bool EightBit::Z80::operator==(const EightBit::Z80& rhs) const noexcept {
 
 	const auto base = IntelProcessor::operator==(rhs);
 
+	auto& left = const_cast<Z80&>(*this);
+	auto& right = const_cast<Z80&>(rhs);
+
 	const auto pins =
-		RFSH() == rhs.RFSH()
-		&& NMI() == rhs.NMI()
-		&& M1() == rhs.M1()
-		&& MREQ() == rhs.MREQ()
-		&& IORQ() == rhs.IORQ()
-		&& RD() == rhs.RD()
-		&& WR() == rhs.WR();
+		left.RFSH() == right.RFSH()
+		&& left.NMI() == right.NMI()
+		&& left.M1() == right.M1()
+		&& left.MREQ() == right.MREQ()
+		&& left.IORQ() == right.IORQ()
+		&& left.RD() == right.RD()
+		&& left.WR() == right.WR();
 
-	auto* z80 = const_cast<Z80*>(this);
-	auto& z80_rhs = const_cast<Z80&>(rhs);
+	left.exxAF();
+	right.exxAF();
+	const auto af = left.AF() == right.AF();
+	left.exxAF();
+	right.exxAF();
 
-	z80->exxAF();
-	z80_rhs.exxAF();
-	const auto af = AF() == rhs.AF();
-	z80->exxAF();
-	z80_rhs.exxAF();
-
-	z80->exx();
-	z80_rhs.exx();
+	left.exx();
+	right.exx();
 	const auto pairs =
-		BC() == rhs.BC()
-		&& DE() == rhs.DE()
-		&& HL() == rhs.HL();
-	z80->exx();
-	z80_rhs.exx();
+		left.BC() == right.BC()
+		&& left.DE() == right.DE()
+		&& left.HL() == right.HL();
+	left.exx();
+	right.exx();
 
 	const auto indices =
-		IX() == rhs.IX()
-		&& IY() == rhs.IY();
+		left.IX() == right.IX()
+		&& left.IY() == right.IY();
 
 	const auto miscellaneous =
-		REFRESH() == rhs.REFRESH()
-		&& IV() == rhs.IV()
-		&& IM() == rhs.IM()
-		&& IFF1() == rhs.IFF1()
-		&& IFF2() == rhs.IFF2();
+		left.REFRESH() == right.REFRESH()
+		&& left.IV() == right.IV()
+		&& left.IM() == right.IM()
+		&& left.IFF1() == right.IFF1()
+		&& left.IFF2() == right.IFF2();
 
 	return base && pins && af && pairs && indices && miscellaneous;
 }
@@ -125,19 +120,19 @@ DEFINE_PIN_LEVEL_CHANGERS(IORQ, Z80);
 DEFINE_PIN_LEVEL_CHANGERS(RD, Z80);
 DEFINE_PIN_LEVEL_CHANGERS(WR, Z80);
 
-const EightBit::register16_t& EightBit::Z80::AF() const noexcept {
+EightBit::register16_t& EightBit::Z80::AF() noexcept {
 	return m_accumulatorFlags[m_accumulatorFlagsSet];
 }
 
-const EightBit::register16_t& EightBit::Z80::BC() const noexcept {
+EightBit::register16_t& EightBit::Z80::BC() noexcept {
 	return m_registers[m_registerSet][BC_IDX];
 }
 
-const EightBit::register16_t& EightBit::Z80::DE() const noexcept {
+EightBit::register16_t& EightBit::Z80::DE() noexcept {
 	return m_registers[m_registerSet][DE_IDX];
 }
 
-const EightBit::register16_t& EightBit::Z80::HL() const noexcept {
+EightBit::register16_t& EightBit::Z80::HL() noexcept {
 	return m_registers[m_registerSet][HL_IDX];
 }
 
@@ -156,11 +151,11 @@ void EightBit::Z80::memoryUpdate(int ticks) noexcept {
 }
 
 void EightBit::Z80::memoryWrite() noexcept {
-	memoryUpdate(1);
+	memoryUpdate();
 }
 
 void EightBit::Z80::refreshMemory() noexcept {
-	assert(lowered(M1()) && "M1 must be lowered to refresh memory");
+	assert(fetchingOpCode() && "M1 must be lowered to refresh memory");
 	BUS().ADDRESS() = { REFRESH(), IV() };
 	lowerRFSH();
 		tick();
@@ -175,14 +170,14 @@ uint8_t EightBit::Z80::memoryRead() noexcept {
 	lowerMREQ();
 		lowerRD();
 			tick();
-			const auto data = IntelProcessor::memoryRead();
+			IntelProcessor::memoryRead();
 		raiseRD();
 	raiseMREQ();
-	if (lowered(M1()))
+	if (fetchingOpCode())
 		refreshMemory();
 	tick();
 	ReadMemory.fire();
-	return data;
+	return BUS().DATA();
 }
 
 void EightBit::Z80::handleRESET() noexcept {
@@ -204,9 +199,9 @@ void EightBit::Z80::handleNMI() noexcept {
 	restart(0x66);
 }
 
-uint8_t EightBit::Z80::readDataUnderInterrupt() {
+uint8_t EightBit::Z80::readDataUnderInterrupt() noexcept {
 	lowerM1();
-		tick(3);
+		tick(2);
 		lowerIORQ();
 			tick();
 			const auto data = BUS().DATA();
@@ -215,6 +210,7 @@ uint8_t EightBit::Z80::readDataUnderInterrupt() {
 		refreshMemory();
 		assert(cycles() == 5);
 	raiseM1();
+	tick();
 	return data;
 }
 
@@ -222,8 +218,9 @@ void EightBit::Z80::handleINT() noexcept {
 
 	IntelProcessor::handleINT();
 
-	const auto data = readDataUnderInterrupt();
 	tick();
+
+	const auto data = readDataUnderInterrupt();
 	assert(cycles() == 6);
 
 	switch (IM()) {
@@ -235,24 +232,46 @@ void EightBit::Z80::handleINT() noexcept {
 		assert(cycles() == 13);
 		break;
 	case 2:
-		tick();
 		MEMPTR() = Processor::getWordPaged(IV(), data);
 		call(MEMPTR());
-		assert(cycles() == 13);
+		assert(cycles() == 19);
 		break;
 	default:
 		UNREACHABLE;
 	}
 }
 
-void EightBit::Z80::disableInterrupts() {
+void EightBit::Z80::disableInterrupts() noexcept {
 	IFF1() = IFF2() = false;
 }
 
-void EightBit::Z80::enableInterrupts() {
+void EightBit::Z80::enableInterrupts() noexcept {
 	IFF1() = IFF2() = true;
 }
 
+bool EightBit::Z80::convertCondition(int flag) noexcept {
+	switch (flag) {
+	case 0:
+		return zero() == 0;
+	case 1:
+		return zero() != 0;
+	case 2:
+		return carry() == 0;
+	case 3:
+		return carry() != 0;
+	case 4:
+		return parity() == 0;
+	case 5:
+		return parity() != 0;
+	case 6:
+		return sign() == 0;
+	case 7:
+		return sign() != 0;
+	default:
+		UNREACHABLE;
+	}
+}
+
 void EightBit::Z80::returnConditionalFlag(const int flag) noexcept {
 	const auto condition = convertCondition(flag);
 	tick();
@@ -269,8 +288,7 @@ void EightBit::Z80::reti() noexcept {
 	retn();
 }
 
-
-void EightBit::Z80::call(register16_t destination) {
+void EightBit::Z80::call(register16_t destination) noexcept {
 	tick();
 	Processor::call(destination);
 }
@@ -280,6 +298,70 @@ void EightBit::Z80::jumpRelative(int8_t offset) noexcept {
 	tick(5);
 }
 
+uint8_t EightBit::Z80::increment(uint8_t operand) noexcept {
+	clearBit(NF);
+	const uint8_t result = operand + 1;
+	adjustSZXY(result);
+	setBit(VF, result == Bit7);
+	clearBit(HC, lowNibble(result));
+	return result;
+}
+
+uint8_t EightBit::Z80::decrement(uint8_t operand) noexcept {
+	setBit(NF);
+	clearBit(HC, lowNibble(operand));
+	const uint8_t result = operand - 1;
+	adjustSZXY(result);
+	setBit(VF, result == Mask7);
+	return result;
+}
+
+void EightBit::Z80::add(uint8_t value, int carry) noexcept {
+
+	const auto operand = A();
+
+	intermediate() = operand + value + carry;
+	const auto result = intermediate().low;
+
+	adjustHalfCarryAdd(operand, value, result);
+	adjustOverflowAdd(operand, value, result);
+
+	clearBit(NF);
+	setBit(CF, carryTest(intermediate().high));
+	adjustSZXY(result);
+
+	A() = result;
+}
+
+void EightBit::Z80::adc(uint8_t value) noexcept {
+	add(value, carry());
+}
+
+void EightBit::Z80::sub(uint8_t value, int carry) noexcept {
+	adjustSZXY(A() = subtract(value, carry));
+}
+
+void EightBit::Z80::sbc(uint8_t value) noexcept {
+	sub(value, carry());
+}
+
+uint8_t EightBit::Z80::subtract(uint8_t value, int carry) noexcept {
+
+	const auto operand = A();
+
+	const register16_t subtraction = operand - value - carry;
+	const auto result = subtraction.low;
+
+	adjustHalfCarrySub(operand, value, result);
+	adjustOverflowSub(operand, value, result);
+
+	setBit(NF);
+	setBit(CF, carryTest(subtraction.high));
+	adjustSZ(result);
+
+	return result;
+}
+
 void EightBit::Z80::sbc(const register16_t value) noexcept {
 
 	const auto operand = HL2();
@@ -303,6 +385,7 @@ void EightBit::Z80::sbc(const register16_t value) noexcept {
 	MEMPTR() = operand + 1;
 
 	HL2() = intermediate();
+	tick(7);
 }
 
 void EightBit::Z80::adc(const register16_t value) noexcept {
@@ -324,7 +407,7 @@ void EightBit::Z80::add(const register16_t value, int carry) noexcept {
 	const auto operand = HL2();
 
 	const auto addition = operand.word + value.word + carry;
-	intermediate().word = addition;
+	intermediate() = addition;
 
 	clearBit(NF);
 	setBit(CF, addition & Bit16);
@@ -334,6 +417,7 @@ void EightBit::Z80::add(const register16_t value, int carry) noexcept {
 	MEMPTR() = operand + 1;
 
 	HL2() = intermediate();
+	tick(7);
 }
 
 void EightBit::Z80::xhtl(register16_t& exchange) noexcept {
@@ -346,19 +430,177 @@ void EightBit::Z80::xhtl(register16_t& exchange) noexcept {
 	--BUS().ADDRESS();
 	BUS().DATA() = exchange.low;
 	exchange.low = MEMPTR().low;
-	memoryUpdate(1);
+	memoryUpdate();
 	tick(2);
 }
 
+void EightBit::Z80::andr(uint8_t value) noexcept {
+	setBit(HC);
+	clearBit(CF | NF);
+	adjustSZPXY(A() &= value);
+}
+
+void EightBit::Z80::xorr(uint8_t value) noexcept {
+	clearBit(HC | CF | NF);
+	adjustSZPXY(A() ^= value);
+}
+
+void EightBit::Z80::orr(uint8_t value) noexcept {
+	clearBit(HC | CF | NF);
+	adjustSZPXY(A() |= value);
+}
+
+void EightBit::Z80::compare(uint8_t value) noexcept {
+	subtract(value);
+	adjustXY(value);
+}
+
+uint8_t EightBit::Z80::rlc(uint8_t operand) noexcept {
+	clearBit(NF | HC);
+	const auto carry = operand & Bit7;
+	setBit(CF, carry);
+	const uint8_t result = (operand << 1) | (carry >> 7);
+	adjustXY(result);
+	return result;
+}
+
+uint8_t EightBit::Z80::rrc(uint8_t operand) noexcept {
+	clearBit(NF | HC);
+	const auto carry = operand & Bit0;
+	setBit(CF, carry);
+	const uint8_t result = (operand >> 1) | (carry << 7);
+	adjustXY(result);
+	return result;
+}
+
+uint8_t EightBit::Z80::rl(uint8_t operand) noexcept {
+	clearBit(NF | HC);
+	const auto carrying = carry();
+	setBit(CF, operand & Bit7);
+	const uint8_t result = (operand << 1) | carrying;
+	adjustXY(result);
+	return result;
+}
+
+uint8_t EightBit::Z80::rr(uint8_t operand) noexcept {
+	clearBit(NF | HC);
+	const auto carrying = carry();
+	setBit(CF, operand & Bit0);
+	const uint8_t result = (operand >> 1) | (carrying << 7);
+	adjustXY(result);
+	return result;
+}
+
+uint8_t EightBit::Z80::sla(uint8_t operand) noexcept {
+	clearBit(NF | HC);
+	setBit(CF, operand & Bit7);
+	const uint8_t result = operand << 1;
+	adjustXY(result);
+	return result;
+}
+
+uint8_t EightBit::Z80::sra(uint8_t operand) noexcept {
+	clearBit(NF | HC);
+	setBit(CF, operand & Bit0);
+	const uint8_t result = (operand >> 1) | (operand & Bit7);
+	adjustXY(result);
+	return result;
+}
+
+uint8_t EightBit::Z80::sll(uint8_t operand) noexcept {
+	clearBit(NF | HC);
+	setBit(CF, operand & Bit7);
+	const uint8_t result = (operand << 1) | Bit0;
+	adjustXY(result);
+	return result;
+}
+
+uint8_t EightBit::Z80::srl(uint8_t operand) noexcept {
+	clearBit(NF | HC);
+	setBit(CF, operand & Bit0);
+	const uint8_t result = (operand >> 1) & ~Bit7;
+	adjustXY(result);
+	setBit(ZF, result);
+	return result;
+}
+
+void EightBit::Z80::bit(int n, uint8_t operand) noexcept {
+	setBit(HC);
+	clearBit(NF);
+	const auto discarded = operand & Chip::bit(n);
+	adjustSZ(discarded);
+	clearBit(PF, discarded);
+}
+
+void EightBit::Z80::daa() noexcept {
+
+	auto updated = A();
+
+	const auto lowAdjust = halfCarry() || (lowNibble(A()) > 9);
+	const auto highAdjust = carry() || (A() > 0x99);
+
+	if (subtracting()) {
+		if (lowAdjust)
+			updated -= 6;
+		if (highAdjust)
+			updated -= 0x60;
+	} else {
+		if (lowAdjust)
+			updated += 6;
+		if (highAdjust)
+			updated += 0x60;
+	}
+
+	adjustStatusFlags((F() & (CF | NF) | (A() > 0x99 ? CF : 0) | halfCarryTest(A() ^ updated)));
+	adjustSZPXY(A() = updated);
+}
+
+void EightBit::Z80::scf() noexcept {
+	setBit(CF);
+	clearBit(HC | NF);
+	adjustXY((Q() ^ F()) | A());
+}
+
+void EightBit::Z80::ccf() noexcept {
+	clearBit(NF);
+	const auto carrying = carry();
+	setBit(HC, carrying);
+	clearBit(CF, carrying);
+	adjustXY(((Q() ^ F()) | A()));
+}
+
+void EightBit::Z80::cpl() noexcept {
+	setBit(HC | NF);
+	IntelProcessor::cpl();
+	adjustXY(A());
+}
+
+void EightBit::Z80::neg() noexcept {
+
+	setBit(PF, A() == Bit7);
+	setBit(CF, A());
+	setBit(NF);
+
+	auto original = A();
+
+	A() = (~A() + 1);	// two's complement
+
+	adjustHalfCarrySub(0U, original, A());
+	adjustOverflowSub(0U, original, A());
+
+	adjustSZXY(A());
+}
+
+
 void EightBit::Z80::blockCompare() noexcept {
 
-	const auto data = IntelProcessor::memoryRead(HL());
-	uint8_t result = A() - data;
+	IntelProcessor::memoryRead(HL());
+	uint8_t result = A() - BUS().DATA();
 
 	setBit(PF, --BC().word);
 
 	adjustSZ(result);
-	adjustHalfCarrySub(A(), data, result);
+	adjustHalfCarrySub(A(), BUS().DATA(), result);
 	setBit(NF);
 
 	result -= (halfCarry() >> 4);
@@ -395,15 +637,15 @@ void EightBit::Z80::cpdr() noexcept {
 		repeatBlockInstruction();
 		tick(5);
 	} else {
-		MEMPTR().word = PC().word - 2;
+		MEMPTR() = PC().word - 2;
 		tick(2);
 	}
 }
 
 void EightBit::Z80::blockLoad() noexcept {
-	const auto data = IntelProcessor::memoryRead(HL());
+	IntelProcessor::memoryRead(HL());
 	IntelProcessor::memoryWrite(DE());
-	const auto xy = A() + data;
+	const auto xy = A() + BUS().DATA();
 	setBit(XF, xy & Bit3);
 	setBit(YF, xy & Bit1);
 	clearBit(NF | HC);
@@ -443,7 +685,7 @@ void EightBit::Z80::repeatBlockInstruction() noexcept {
 	adjustXY(PC().high);
 }
 
-void EightBit::Z80::adjustBlockRepeatFlagsIO() {
+void EightBit::Z80::adjustBlockRepeatFlagsIO() noexcept {
 	if (carry() != 0) {
 		const auto negative = signTest(BUS().DATA()) != 0;
 		const uint8_t direction = B() + (negative ? -1 : +1);
@@ -461,11 +703,11 @@ void EightBit::Z80::adjustBlockInputOutputFlags(int basis) noexcept {
 }
 
 void EightBit::Z80::adjustBlockInFlagsIncrement() noexcept {
-	adjustBlockInputOutputFlags((C() + 1) + BUS().DATA());
+	adjustBlockInputOutputFlags((uint8_t)(C() + 1) + BUS().DATA());
 }
 
 void EightBit::Z80::adjustBlockInFlagsDecrement() noexcept {
-	adjustBlockInputOutputFlags((C() - 1) + BUS().DATA());
+	adjustBlockInputOutputFlags((uint8_t)(C() - 1) + BUS().DATA());
 }
 
 void EightBit::Z80::adjustBlockOutFlags() noexcept {
@@ -478,7 +720,7 @@ void EightBit::Z80::blockIn() noexcept {
 	tick();
 	readPort(BC());
 	BUS().ADDRESS() = HL();
-	memoryUpdate(1);
+	memoryUpdate();
 	adjustSZXY(--B());
 	setBit(NF, BUS().DATA() & SF);
 }
@@ -555,7 +797,8 @@ void EightBit::Z80::otdr() noexcept {
 }
 
 void EightBit::Z80::rrd(register16_t address, uint8_t& update) noexcept {
-	(MEMPTR() = BUS().ADDRESS() = address)++;
+	MEMPTR() = BUS().ADDRESS() = address;
+	++MEMPTR();
 	const auto memory = memoryRead();
 	tick(4);
 	IntelProcessor::memoryWrite(promoteNibble(update) | highNibble(memory));
@@ -565,7 +808,8 @@ void EightBit::Z80::rrd(register16_t address, uint8_t& update) noexcept {
 }
 
 void EightBit::Z80::rld(register16_t address, uint8_t& update) noexcept {
-	(MEMPTR() = BUS().ADDRESS() = address)++;
+	MEMPTR() = BUS().ADDRESS() = address;
+	++MEMPTR();
 	const auto memory = memoryRead();
 	tick(4);
 	IntelProcessor::memoryWrite(promoteNibble(memory) | lowNibble(update));
@@ -663,12 +907,14 @@ uint8_t EightBit::Z80::fetchInstruction() noexcept {
 }
 
 void EightBit::Z80::loadAccumulatorIndirect(addresser_t addresser) noexcept {
-	(MEMPTR() = BUS().ADDRESS() = addresser())++;
+	MEMPTR() = BUS().ADDRESS() = addresser();
+	++MEMPTR();
 	A() = memoryRead();
 }
 
 void EightBit::Z80::storeAccumulatorIndirect(addresser_t addresser) noexcept {
-	(MEMPTR() = BUS().ADDRESS() = addresser())++;
+	MEMPTR() = BUS().ADDRESS() = addresser();
+	++MEMPTR();
 	MEMPTR().high = BUS().DATA() = A();
 	memoryWrite();
 }
@@ -677,12 +923,13 @@ void EightBit::Z80::readInternalRegister(reader_t reader) noexcept {
 	adjustSZXY(A() = reader());
 	clearBit(NF | HC);
 	setBit(PF, IFF2());
+	tick();
 }
 
 EightBit::register16_t& EightBit::Z80::HL2() noexcept {
-	if (UNLIKELY(m_prefixDD))
+	if (m_prefixDD)
 		return IX();
-	if (UNLIKELY(m_prefixFD))
+	if (m_prefixFD)
 		return IY();
 	return HL();
 }
@@ -755,7 +1002,6 @@ uint8_t& EightBit::Z80::R(const int r, MemoryMapping::AccessLevel access) noexce
 }
 
 void EightBit::Z80::R(const int r, const uint8_t value, const int ticks) noexcept {
-
 	R(r, MemoryMapping::AccessLevel::WriteOnly) = value;
 	if (r == 6)
 		memoryUpdate(ticks);
@@ -944,7 +1190,6 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p
 			default:
 				UNREACHABLE;
 			}
-			tick(7);
 			break;
 		case 3:	// Retrieve/store register pair from/to immediate address
 			BUS().ADDRESS() = fetchWord();
@@ -1004,11 +1249,9 @@ void EightBit::Z80::executeED(const int x, const int y, const int z, const int p
 				break;
 			case 2:	// LD A,I
 				readInternalRegister([this]() { return IV(); });
-				tick();
 				break;
 			case 3:	// LD A,R
 				readInternalRegister([this]() { return REFRESH(); });
-				tick();
 				break;
 			case 4:	// RRD
 				rrd(HL(), A());
@@ -1135,7 +1378,6 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in
 				break;
 			case 1:	// ADD HL,rp
 				add(RP(p));
-				tick(7);
 				break;
 			default:
 				UNREACHABLE;

Z80/test/Board.cpp

@@ -17,7 +17,7 @@ void Board::lowerPOWER() noexcept {
 	EightBit::Bus::lowerPOWER();
 }
 
-void Board::initialise() {
+void Board::initialise() noexcept {
 
 	auto romDirectory = m_configuration.getRomDirectory();
 	m_ram.load(romDirectory + "/zexall.com", 0x100);	// Cringle/Bartholomew

Z80/test/Board.h

@@ -16,12 +16,12 @@ class Board : public EightBit::Bus {
 public:
 	Board(const Configuration& configuration);
 
-	EightBit::Z80& CPU() noexcept { return m_cpu; }
+	EightBit::Z80& CPU() { return m_cpu; }
 
 	void raisePOWER() noexcept final;
 	void lowerPOWER() noexcept final;
 
-	void initialise() final;
+	void initialise() noexcept final;
 
 protected:
 	EightBit::MemoryMapping mapping(uint16_t address) noexcept final {

inc/BigEndianProcessor.h

@@ -8,7 +8,8 @@ namespace EightBit {
 
 	class BigEndianProcessor : public Processor {
 	public:
-		virtual ~BigEndianProcessor() noexcept {};
+		virtual ~BigEndianProcessor() noexcept = default;
+		BigEndianProcessor(const BigEndianProcessor& rhs) noexcept;
 
 		[[nodiscard]] register16_t peekWord(register16_t address) noexcept final;
 		void pokeWord(register16_t address, register16_t value) noexcept final;
@@ -16,15 +17,15 @@ namespace EightBit {
 	protected:
 		BigEndianProcessor(Bus& memory) noexcept;
 
-		[[nodiscard]] register16_t getWord() override;
-		void setWord(register16_t value) override;
+		[[nodiscard]] register16_t getWord() noexcept override;
+		void setWord(register16_t value) noexcept override;
 
-		[[nodiscard]] register16_t getWordPaged() override;
-		void setWordPaged(register16_t value) override;
+		[[nodiscard]] register16_t getWordPaged() noexcept override;
+		void setWordPaged(register16_t value) noexcept override;
 
-		[[nodiscard]] register16_t fetchWord() final;
+		[[nodiscard]] register16_t fetchWord() noexcept override;
 
-		void pushWord(register16_t value) final;
-		[[nodiscard]] register16_t popWord() final;
+		void pushWord(register16_t value) noexcept override;
+		[[nodiscard]] register16_t popWord() noexcept override;
 	};
 }

inc/Bus.h

@@ -26,20 +26,20 @@ namespace EightBit {
 		[[nodiscard]] constexpr auto DATA() const noexcept { return m_data; }
 		[[nodiscard]] constexpr auto& DATA() noexcept { return m_data; }
 
-		[[nodiscard]] virtual uint8_t peek(const uint16_t address) noexcept { return reference(address); }
+		[[nodiscard]] uint8_t peek(const uint16_t address) noexcept { return reference(address); }
 		[[nodiscard]] auto peek(const register16_t address) noexcept { return peek(address.word); }
 
 		void poke(const uint8_t value) noexcept { reference() = value; }
-		virtual void poke(const uint16_t address, const uint8_t value) noexcept { reference(address) = value; }
+		void poke(const uint16_t address, const uint8_t value) noexcept { reference(address) = value; }
 		void poke(const register16_t address, const uint8_t value) noexcept { poke(address.word, value); }
 
-		[[nodiscard]] uint8_t read();
-		void write();
+		[[nodiscard]] uint8_t read() noexcept;
+		void write() noexcept;
 
 		virtual void raisePOWER() noexcept;
 		virtual void lowerPOWER() noexcept;
 
-		virtual void initialise() = 0;
+		virtual void initialise() noexcept = 0;
 
 	protected:
 		[[nodiscard]] uint8_t& reference(uint16_t address) noexcept;

inc/ClockedChip.h

@@ -14,12 +14,12 @@ namespace EightBit {
 
 		[[nodiscard]] constexpr auto cycles() const noexcept { return m_cycles; }
 
-		void tick() {
+		void tick() noexcept {
 			++m_cycles;
 			Ticked.fire();
 		}
 
-		void tick(int extra) {
+		void tick(int extra) noexcept {
 			for (int i = 0; i < extra; ++i)
 				tick();
 		}

inc/Device.h

@@ -10,17 +10,17 @@
 	Signal<EventArgs> Lowered ## name;
 
 #define DECLARE_PIN_LEVEL_RAISE(name) \
-	virtual void raise ## name();
+	virtual void raise ## name() noexcept;
 
 #define DECLARE_PIN_LEVEL_LOWER(name) \
-	virtual void lower ## name();
+	virtual void lower ## name() noexcept;
 
 #define DECLARE_PIN_LEVEL_CHANGERS(name) \
 	DECLARE_PIN_LEVEL_RAISE(name) \
 	DECLARE_PIN_LEVEL_LOWER(name)
 
 #define DEFINE_PIN_LEVEL_RAISE(name, within) \
-	void EightBit:: within ::raise ## name() { \
+	void EightBit:: within ::raise ## name() noexcept { \
 		if (lowered( name ())) { \
 			Raising ## name.fire(); \
 			raise( name ()); \
@@ -29,7 +29,7 @@
 	}
 
 #define DEFINE_PIN_LEVEL_LOWER(name, within) \
-	void EightBit:: within ::lower ## name() { \
+	void EightBit:: within ::lower ## name() noexcept { \
 		if (raised( name ())) { \
 			Lowering ## name.fire(); \
 			lower( name ()); \
@@ -44,25 +44,6 @@
 #define DECLARE_PIN_MEMBER(name) \
 	PinLevel m_## name ## _Line = PinLevel::Low;
 
-#define DEFINE_PIN_ACTIVATOR(name, on, off) \
-	template <class T> class _Activate ## name final { \
-		T& m_parent; \
-	public: \
-		_Activate ## name(T& parent) noexcept \
-		: m_parent(parent) { \
-			m_parent. on ## name(); \
-		 } \
-		~_Activate ## name() noexcept { \
-			m_parent. off ## name(); \
-		} \
-	};
-
-#define DEFINE_PIN_ACTIVATOR_LOW(name) \
-	DEFINE_PIN_ACTIVATOR(name, lower, raise)
-
-#define DEFINE_PIN_ACTIVATOR_HIGH(name) \
-	DEFINE_PIN_ACTIVATOR(name, raise, lower)
-
 #define DECLARE_PIN(name, visibility) \
 	public: \
 		DECLARE_PIN_SIGNALS(name) \
@@ -114,6 +95,6 @@ namespace EightBit {
 		[[nodiscard]] constexpr bool powered() const noexcept { return raised(POWER()); }
 
 	protected:
-		Device() noexcept {};
+		Device() noexcept = default;
 	};
 }

inc/IntelProcessor.h

@@ -9,16 +9,6 @@
 #include "Signal.h"
 #include "EightBitCompilerDefinitions.h"
 
-#define NON_CONST_ACCESSOR(accessor, type) \
-	[[nodiscard]] constexpr auto& accessor() noexcept { \
-		const auto& consted = *this; \
-		const auto& reference = consted.accessor(); \
-		return const_cast<type&>(reference); \
-	}
-
-#define NON_CONST_REGISTOR_ACCESSOR(accessor) \
-	NON_CONST_ACCESSOR(accessor, register16_t)
-
 namespace EightBit {
 
 	class Bus;
@@ -52,35 +42,32 @@ namespace EightBit {
 		}
 
 		[[nodiscard]] constexpr auto& MEMPTR() noexcept { return m_memptr; }
-		[[nodiscard]] constexpr auto MEMPTR() const noexcept { return m_memptr; }
-
 		[[nodiscard]] constexpr auto& SP() noexcept { return m_sp; }
-		[[nodiscard]] register16_t SP() const noexcept { return m_sp; }
 
-		[[nodiscard]] virtual const register16_t& AF() const noexcept = 0;
-		NON_CONST_REGISTOR_ACCESSOR(AF);
+		[[nodiscard]] virtual register16_t& AF() noexcept = 0;
 		[[nodiscard]] auto& A() noexcept { return AF().high; }
 		[[nodiscard]] auto& F() noexcept { return AF().low; }
 
-		[[nodiscard]] virtual const register16_t& BC() const noexcept = 0;
-		NON_CONST_REGISTOR_ACCESSOR(BC);
+		[[nodiscard]] virtual register16_t& BC() noexcept = 0;
 		[[nodiscard]] auto& B() noexcept { return BC().high; }
 		[[nodiscard]] auto& C() noexcept { return BC().low; }
 
-		[[nodiscard]] virtual const register16_t& DE() const noexcept = 0;
-		NON_CONST_REGISTOR_ACCESSOR(DE);
+		[[nodiscard]] virtual register16_t& DE() noexcept = 0;
 		[[nodiscard]] auto& D() noexcept { return DE().high; }
 		[[nodiscard]] auto& E() noexcept { return DE().low; }
 
-		[[nodiscard]] virtual const register16_t& HL() const noexcept = 0;
-		NON_CONST_REGISTOR_ACCESSOR(HL);
+		[[nodiscard]] virtual register16_t& HL() noexcept = 0;
 		[[nodiscard]] auto& H() noexcept { return HL().high; }
 		[[nodiscard]] auto& L() noexcept { return HL().low; }
 
 		DECLARE_PIN_OUTPUT(HALT)
 
+	public:
+		[[nodiscard]] constexpr bool halted() const noexcept { return lowered(HALT()); }
+		[[nodiscard]] constexpr bool proceeding() const noexcept { return !halted(); }
+
 	protected:
-		IntelProcessor(Bus& bus);
+		IntelProcessor(Bus& bus) noexcept;
 
 		template<class T> [[nodiscard]] static constexpr uint8_t adjustSign(uint8_t f, const uint8_t value) noexcept {
 			return setBit(f, T::SF, value & T::SF);
@@ -138,65 +125,51 @@ namespace EightBit {
 			return calculateHalfCarry(m_halfCarryTableSub, before, value, calculation);
 		}
 
-		virtual void disableInterrupts() = 0;
+		virtual void disableInterrupts() noexcept = 0;
+		virtual void enableInterrupts() noexcept = 0;
 
-		virtual void enableInterrupts() = 0;
+		void handleRESET() noexcept override;
+		void handleINT() noexcept override;
 
-		void handleRESET() override;
-		void handleINT() override;
-
-		void push(uint8_t value) final;
-		[[nodiscard]] uint8_t pop() final;
+		void push(uint8_t value) noexcept final;
+		[[nodiscard]] uint8_t pop() noexcept final;
 
 		//
 
-		register16_t& incrementPC() override;
-		uint8_t fetchInstruction() override;
+		register16_t& incrementPC() noexcept override;
+		uint8_t fetchInstruction() noexcept override;
 
 		//
 
-		[[nodiscard]] register16_t getWord() final;
-		void setWord(register16_t value) final;
+		[[nodiscard]] register16_t getWord() noexcept final;
+		void setWord(register16_t value) noexcept final;
 
 		//
 
-		void restart(uint8_t address);
-		void callConditional(bool condition);
-		virtual void jumpConditional(bool condition);
-		void jumpRelativeConditional(bool condition);
-		virtual void returnConditional(bool condition);
-		void jumpIndirect();
-		void jump();
-		void callIndirect();
-		void call();
-		virtual void call(register16_t destination);
+		void restart(uint8_t address) noexcept;
+		void callConditional(bool condition) noexcept;
+		virtual void jumpConditional(bool condition) noexcept;
+		void jumpRelativeConditional(bool condition) noexcept;
+		virtual void returnConditional(bool condition) noexcept;
+		void jumpIndirect() noexcept;
+		void jump() noexcept;
+		void callIndirect() noexcept;
+		void call() noexcept;
+		virtual void call(register16_t destination) noexcept;
 		virtual void jumpRelative(int8_t offset) noexcept;
-		void jumpRelative(uint8_t offset) noexcept { jumpRelative((int8_t)offset); }
-		void ret() override;
+		void jumpRelative(uint8_t offset) noexcept { jumpRelative(static_cast<int8_t>(offset)); }
+		void ret() noexcept override;
 
 		void resetWorkingRegisters() noexcept;
 
 		[[nodiscard]] virtual bool convertCondition(int flag) noexcept = 0;
 
-		virtual void jumpConditionalFlag(int flag) {
-			jumpConditional(convertCondition(flag));
-		}
+		virtual void jumpConditionalFlag(int flag) noexcept;
+		virtual void jumpRelativeConditionalFlag(int flag) noexcept;
+		virtual void returnConditionalFlag(int flag) noexcept;
+		virtual void callConditionalFlag(int flag) noexcept;
 
-		virtual void jumpRelativeConditionalFlag(int flag) {
-			jumpRelativeConditional(convertCondition(flag));
-		}
-
-		virtual void returnConditionalFlag(int flag) {
-			returnConditional(convertCondition(flag));
-		}
-
-		virtual void callConditionalFlag(int flag) {
-			callConditional(convertCondition(flag));
-		}
-
-		virtual void cpl() noexcept {
-			A() = ~A();
-		}
+		virtual void cpl() noexcept;
 
 	private:
 		static std::array<int, 8> m_halfCarryTableAdd;

inc/LittleEndianProcessor.h

@@ -8,6 +8,7 @@ namespace EightBit {
 
 	class LittleEndianProcessor : public Processor {
 	public:
+		virtual ~LittleEndianProcessor() noexcept = default;
 		LittleEndianProcessor(const LittleEndianProcessor& rhs) noexcept;
 
 		[[nodiscard]] register16_t peekWord(register16_t address) noexcept final;
@@ -16,15 +17,15 @@ namespace EightBit {
 	protected:
 		LittleEndianProcessor(Bus& memory) noexcept;
 
-		[[nodiscard]] register16_t getWord() override;
-		void setWord(register16_t value) override;
+		[[nodiscard]] register16_t getWord() noexcept override;
+		void setWord(register16_t value) noexcept override;
 
-		[[nodiscard]] register16_t getWordPaged() override;
-		void setWordPaged(register16_t value) override;
+		[[nodiscard]] register16_t getWordPaged() noexcept override;
+		void setWordPaged(register16_t value) noexcept override;
 
-		[[nodiscard]] register16_t fetchWord() final;
+		[[nodiscard]] register16_t fetchWord() noexcept override;
 
-		void pushWord(register16_t value) override;
-		[[nodiscard]] register16_t popWord() override;
+		void pushWord(register16_t value) noexcept override;
+		[[nodiscard]] register16_t popWord() noexcept override;
 	};
 }

inc/Processor.h

@@ -57,53 +57,53 @@ namespace EightBit {
 		[[nodiscard]] constexpr auto& opcode() noexcept { return m_opcode; }
 		[[nodiscard]] constexpr auto& BUS() noexcept { return m_bus; }
 
-		virtual void handleRESET();
-		virtual void handleINT();
+		virtual void handleRESET() noexcept;
+		virtual void handleINT() noexcept;
 
-		void memoryWrite(register16_t address, uint8_t data);
-		void memoryWrite(register16_t address);
-		void memoryWrite(uint8_t data);
-		virtual void memoryWrite();
-		virtual void busWrite();
+		void memoryWrite(register16_t address, uint8_t data) noexcept;
+		void memoryWrite(register16_t address) noexcept;
+		void memoryWrite(uint8_t data) noexcept;
+		virtual void memoryWrite() noexcept;
+		virtual void busWrite() noexcept;
 
-		uint8_t memoryRead(register16_t address);
-		virtual uint8_t memoryRead();
-		virtual uint8_t busRead();
+		uint8_t memoryRead(register16_t address) noexcept;
+		virtual uint8_t memoryRead() noexcept;
+		virtual uint8_t busRead() noexcept;
 
-		virtual register16_t& incrementPC();
-		virtual register16_t& decrementPC();
+		virtual register16_t& incrementPC() noexcept;
+		virtual register16_t& decrementPC() noexcept;
 
-		virtual void immediateAddress();
+		virtual void immediateAddress() noexcept;
 
-		uint8_t fetchByte();
-		virtual uint8_t fetchInstruction();
+		uint8_t fetchByte() noexcept;
+		virtual uint8_t fetchInstruction() noexcept;
 
-		[[nodiscard]] virtual register16_t getWord() = 0;
-		virtual void setWord(register16_t value) = 0;
+		[[nodiscard]] virtual register16_t getWord() noexcept = 0;
+		virtual void setWord(register16_t value) noexcept = 0;
 
-		[[nodiscard]] register16_t getWordPaged(register16_t address);
-		[[nodiscard]] register16_t getWordPaged(uint8_t page, uint8_t offset);
-		[[nodiscard]] virtual register16_t getWordPaged() = 0;
-		void setWordPaged(register16_t address, register16_t value);
-		void setWordPaged(uint8_t page, uint8_t offset, register16_t value);
-		virtual void setWordPaged(register16_t value) = 0;
+		[[nodiscard]] register16_t getWordPaged(register16_t address) noexcept;
+		[[nodiscard]] register16_t getWordPaged(uint8_t page, uint8_t offset) noexcept;
+		[[nodiscard]] virtual register16_t getWordPaged() noexcept = 0;
+		void setWordPaged(register16_t address, register16_t value) noexcept;
+		void setWordPaged(uint8_t page, uint8_t offset, register16_t value) noexcept;
+		virtual void setWordPaged(register16_t value) noexcept = 0;
 
-		[[nodiscard]] virtual register16_t fetchWord() = 0;
+		[[nodiscard]] virtual register16_t fetchWord() noexcept = 0;
 
-		virtual void push(uint8_t value) = 0;
-		[[nodiscard]] virtual uint8_t pop() = 0;
+		virtual void push(uint8_t value) noexcept = 0;
+		[[nodiscard]] virtual uint8_t pop() noexcept = 0;
 
-		virtual void pushWord(register16_t value) = 0;
-		[[nodiscard]] virtual register16_t popWord() = 0;
+		virtual void pushWord(register16_t value) noexcept = 0;
+		[[nodiscard]] virtual register16_t popWord() noexcept = 0;
 
-		[[nodiscard]] register16_t getWord(register16_t address);
-		void setWord(register16_t address, register16_t value);
+		[[nodiscard]] register16_t getWord(register16_t address) noexcept;
+		void setWord(register16_t address, register16_t value) noexcept;
 
 		void jump(const register16_t destination) noexcept;
 		void jump(uint16_t destination) noexcept;
 
-		virtual void call(register16_t destination);
-		virtual void ret();
+		virtual void call(register16_t destination) noexcept;
+		virtual void ret() noexcept;
 
 	private:
 		Bus& m_bus;

inc/Ram.h

@@ -8,7 +8,7 @@ namespace EightBit {
 	class Ram : public Rom {
 	public:
 		Ram(size_t size = 0) noexcept;
-		virtual ~Ram() = default;
+		virtual ~Ram() noexcept = default;
 
 		[[nodiscard]] uint8_t& reference(uint16_t address) noexcept final;
 		void poke(uint16_t address, uint8_t value) noexcept final;

inc/Rom.h

@@ -26,10 +26,10 @@ namespace EightBit {
 		static int load(std::string path, std::vector<uint8_t>& output, int writeOffset = 0, int readOffset = 0, int limit = -1, int maximumSize = -1);
 
 		Rom(size_t size = 0) noexcept;
-		Rom(const Rom& rhs);
-		virtual ~Rom() = default;
-		Rom& operator=(const Rom& rhs);
-		bool operator==(const Rom& rhs) const;
+		Rom(const Rom& rhs) noexcept;
+		virtual ~Rom() noexcept = default;
+		Rom& operator=(const Rom& rhs) noexcept;
+		bool operator==(const Rom& rhs) const noexcept;
 
 		[[nodiscard]] uint16_t size() const noexcept final;
 

inc/Signal.h

@@ -17,7 +17,9 @@ namespace EightBit {
 			m_delegates.push_back(functor);
 		}
 
-		void fire(T& e = EventArgs::empty()) const {
+		void fire(T& e = EventArgs::empty()) const noexcept {
+			const auto firing = !m_delegates.empty();
+			if (firing)
 				for (auto& delegate : m_delegates)
 					delegate(e);
 		}

src/BigEndianProcessor.cpp

@@ -4,44 +4,47 @@
 EightBit::BigEndianProcessor::BigEndianProcessor(Bus& memory) noexcept
 : Processor(memory) {}
 
-EightBit::register16_t EightBit::BigEndianProcessor::getWord() {
+EightBit::BigEndianProcessor::BigEndianProcessor(const BigEndianProcessor& rhs) noexcept
+: Processor(rhs) {}
+
+EightBit::register16_t EightBit::BigEndianProcessor::getWord() noexcept {
 	const auto high = memoryRead();
 	++BUS().ADDRESS();
 	const auto low = memoryRead();
 	return { low, high };
 }
 
-void EightBit::BigEndianProcessor::setWord(const register16_t value) {
+void EightBit::BigEndianProcessor::setWord(const register16_t value) noexcept {
 	memoryWrite(value.high);
 	++BUS().ADDRESS();
 	memoryWrite(value.low);
 }
 
-EightBit::register16_t EightBit::BigEndianProcessor::getWordPaged() {
+EightBit::register16_t EightBit::BigEndianProcessor::getWordPaged() noexcept {
 	const auto high = memoryRead();
 	++BUS().ADDRESS().low;
 	const auto low = memoryRead();
 	return { low, high };
 }
 
-void EightBit::BigEndianProcessor::setWordPaged(const register16_t value) {
+void EightBit::BigEndianProcessor::setWordPaged(const register16_t value) noexcept {
 	memoryWrite(value.high);
 	++BUS().ADDRESS().low;
 	memoryWrite(value.low);
 }
 
-EightBit::register16_t EightBit::BigEndianProcessor::fetchWord() {
-	const auto high = fetchByte();
-	const auto low = fetchByte();
-	return { low, high };
+EightBit::register16_t EightBit::BigEndianProcessor::fetchWord() noexcept {
+	intermediate().high = fetchByte();
+	intermediate().low = fetchByte();
+	return intermediate();
 }
 
-void EightBit::BigEndianProcessor::pushWord(const register16_t value) {
+void EightBit::BigEndianProcessor::pushWord(const register16_t value) noexcept {
 	push(value.low);
 	push(value.high);
 }
 
-EightBit::register16_t EightBit::BigEndianProcessor::popWord() {
+EightBit::register16_t EightBit::BigEndianProcessor::popWord() noexcept {
 	const auto high = pop();
 	const auto low = pop();
 	return { low, high };

src/Bus.cpp

@@ -8,14 +8,14 @@ void EightBit::Bus::raisePOWER() noexcept {}
 
 void EightBit::Bus::lowerPOWER() noexcept {}
 
-uint8_t EightBit::Bus::read() {
+uint8_t EightBit::Bus::read() noexcept {
 	ReadingByte.fire();
 	const auto returned = DATA() = reference();
 	ReadByte.fire();
 	return returned;
 }
 
-void EightBit::Bus::write() {
+void EightBit::Bus::write() noexcept {
 	WritingByte.fire();
 	reference() = DATA();
 	WrittenByte.fire();

src/IntelProcessor.cpp

@@ -4,7 +4,7 @@
 std::array<int, 8> EightBit::IntelProcessor::m_halfCarryTableAdd = { { 0, 0, 1, 0, 1, 0, 1, 1 } };
 std::array<int, 8> EightBit::IntelProcessor::m_halfCarryTableSub = { { 0, 1, 1, 1, 0, 0, 0, 1 } };
 
-EightBit::IntelProcessor::IntelProcessor(Bus& bus)
+EightBit::IntelProcessor::IntelProcessor(Bus& bus) noexcept
 : LittleEndianProcessor(bus) {
 	for (int i = 0; i < 0x100; ++i)
 		m_decodedOpcodes.at(i) = i;
@@ -17,11 +17,9 @@ EightBit::IntelProcessor::IntelProcessor(Bus& bus)
 }
 
 EightBit::IntelProcessor::IntelProcessor(const IntelProcessor& rhs) noexcept
-: LittleEndianProcessor(rhs) {
-
-	m_sp = rhs.m_sp;
-	m_memptr = rhs.m_memptr;
-
+: LittleEndianProcessor(rhs),
+  m_sp(rhs.m_sp),
+  m_memptr(rhs.m_memptr) {
 	HALT() = rhs.HALT();
 }
 
@@ -31,73 +29,72 @@ void EightBit::IntelProcessor::resetWorkingRegisters() noexcept {
 
 DEFINE_PIN_LEVEL_CHANGERS(HALT, IntelProcessor);
 
-void EightBit::IntelProcessor::handleRESET() {
+void EightBit::IntelProcessor::handleRESET() noexcept {
 	Processor::handleRESET();
 	disableInterrupts();
 	Processor::jump(0);
 }
 
-void EightBit::IntelProcessor::handleINT() {
+void EightBit::IntelProcessor::handleINT() noexcept {
 	Processor::handleINT();
-	disableInterrupts();
 	raiseHALT();
+	disableInterrupts();
 }
 
-void EightBit::IntelProcessor::push(const uint8_t value) {
+void EightBit::IntelProcessor::push(const uint8_t value) noexcept {
 	memoryWrite(--SP(), value);
 }
 
-uint8_t EightBit::IntelProcessor::pop() {
+uint8_t EightBit::IntelProcessor::pop() noexcept {
 	return memoryRead(SP()++);
 }
 
-
-EightBit::register16_t& EightBit::IntelProcessor::incrementPC() {
-	if (raised(HALT()))
+EightBit::register16_t& EightBit::IntelProcessor::incrementPC() noexcept {
+	if (proceeding())
 		Processor::incrementPC();
 	return PC();
 }
 
-uint8_t EightBit::IntelProcessor::fetchInstruction() {
+uint8_t EightBit::IntelProcessor::fetchInstruction() noexcept {
 	const auto data = fetchByte();
-	return lowered(HALT()) ? (uint8_t)0 : data;
+	return proceeding() ? data : (uint8_t)0;
 }
 
-EightBit::register16_t EightBit::IntelProcessor::getWord() {
+EightBit::register16_t EightBit::IntelProcessor::getWord() noexcept {
 	const auto returned = LittleEndianProcessor::getWord();
 	MEMPTR() = BUS().ADDRESS();
 	return returned;
 }
 
-void EightBit::IntelProcessor::setWord(const register16_t value) {
+void EightBit::IntelProcessor::setWord(const register16_t value) noexcept {
 	LittleEndianProcessor::setWord(value);
 	MEMPTR() = BUS().ADDRESS();
 }
 
-void EightBit::IntelProcessor::restart(const uint8_t address) {
+void EightBit::IntelProcessor::restart(const uint8_t address) noexcept {
 	MEMPTR() = { address, 0 };
 	call();
 }
 
-void EightBit::IntelProcessor::callConditional(bool condition) {
+void EightBit::IntelProcessor::callConditional(bool condition) noexcept {
 	MEMPTR() = fetchWord();
 	if (condition)
 		call();
 }
 
-void EightBit::IntelProcessor::jumpConditional(bool condition) {
+void EightBit::IntelProcessor::jumpConditional(bool condition) noexcept {
 	MEMPTR() = fetchWord();
 	if (condition)
 		jump();
 }
 
-void EightBit::IntelProcessor::jumpRelativeConditional(bool condition) {
+void EightBit::IntelProcessor::jumpRelativeConditional(bool condition) noexcept {
 	const auto offset = fetchByte();
 	if (condition)
 		jumpRelative(offset);
 }
 
-void EightBit::IntelProcessor::returnConditional(bool condition) {
+void EightBit::IntelProcessor::returnConditional(bool condition) noexcept {
 	if (condition)
 		ret();
 }
@@ -107,42 +104,63 @@ void EightBit::IntelProcessor::jumpRelative(const int8_t offset) noexcept {
 	jump();
 }
 
-
-void EightBit::IntelProcessor::ret() {
+void EightBit::IntelProcessor::ret() noexcept {
 	LittleEndianProcessor::ret();
 	MEMPTR() = PC();
 }
 
-void EightBit::IntelProcessor::jumpIndirect() {
+void EightBit::IntelProcessor::jumpIndirect() noexcept {
 	MEMPTR() = fetchWord();
 	jump();
 }
 
-void EightBit::IntelProcessor::jump() {
+void EightBit::IntelProcessor::jump() noexcept {
 	Processor::jump(MEMPTR());
 }
 
-void EightBit::IntelProcessor::callIndirect() {
+void EightBit::IntelProcessor::callIndirect() noexcept {
 	MEMPTR() = fetchWord();
 	call();
 }
 
-void EightBit::IntelProcessor::call() {
+void EightBit::IntelProcessor::call() noexcept {
 	call(MEMPTR());
 }
 
-void EightBit::IntelProcessor::call(register16_t destination) {
+void EightBit::IntelProcessor::call(register16_t destination) noexcept {
 	Processor::call(destination);
 }
 
+void EightBit::IntelProcessor::jumpConditionalFlag(int flag) noexcept {
+	jumpConditional(convertCondition(flag));
+}
+
+void EightBit::IntelProcessor::jumpRelativeConditionalFlag(int flag) noexcept {
+	jumpRelativeConditional(convertCondition(flag));
+}
+
+void EightBit::IntelProcessor::returnConditionalFlag(int flag) noexcept {
+	returnConditional(convertCondition(flag));
+}
+
+void EightBit::IntelProcessor::callConditionalFlag(int flag) noexcept {
+	callConditional(convertCondition(flag));
+}
+
+void EightBit::IntelProcessor::cpl() noexcept {
+	A() = ~A();
+}
+
 bool EightBit::IntelProcessor::operator==(const EightBit::IntelProcessor& rhs) const noexcept {
+	auto& left = const_cast<IntelProcessor&>(*this);
+	auto& right = const_cast<IntelProcessor&>(rhs);
 	return
 		LittleEndianProcessor::operator==(rhs)
-		&& HALT() == rhs.HALT()
-		&& MEMPTR() == rhs.MEMPTR()
-		&& SP() == rhs.SP()
-		&& AF() == rhs.AF()
-		&& BC() == rhs.BC()
-		&& DE() == rhs.DE()
-		&& HL() == rhs.HL();
+		&& left.HALT() == right.HALT()
+		&& left.MEMPTR() == right.MEMPTR()
+		&& left.SP() == right.SP()
+		&& left.AF() == right.AF()
+		&& left.BC() == right.BC()
+		&& left.DE() == right.DE()
+		&& left.HL() == right.HL();
 }

src/LittleEndianProcessor.cpp

@@ -7,44 +7,44 @@ EightBit::LittleEndianProcessor::LittleEndianProcessor(Bus& memory) noexcept
 EightBit::LittleEndianProcessor::LittleEndianProcessor(const LittleEndianProcessor& rhs) noexcept
 : Processor(rhs) {}
 
-EightBit::register16_t EightBit::LittleEndianProcessor::getWord() {
+EightBit::register16_t EightBit::LittleEndianProcessor::getWord() noexcept {
 	const auto low = memoryRead();
 	++BUS().ADDRESS();
 	const auto high = memoryRead();
 	return { low, high };
 }
 
-void EightBit::LittleEndianProcessor::setWord(const register16_t value) {
+void EightBit::LittleEndianProcessor::setWord(const register16_t value) noexcept {
 	memoryWrite(value.low);
 	++BUS().ADDRESS();
 	memoryWrite(value.high);
 }
 
-EightBit::register16_t EightBit::LittleEndianProcessor::getWordPaged() {
+EightBit::register16_t EightBit::LittleEndianProcessor::getWordPaged() noexcept {
 	const auto low = memoryRead();
 	++BUS().ADDRESS().low;
 	const auto high = memoryRead();
 	return { low, high };
 }
 
-void EightBit::LittleEndianProcessor::setWordPaged(register16_t value) {
+void EightBit::LittleEndianProcessor::setWordPaged(register16_t value) noexcept {
 	memoryWrite(value.low);
 	++BUS().ADDRESS().low;
 	memoryWrite(value.high);
 }
 
-EightBit::register16_t EightBit::LittleEndianProcessor::fetchWord() {
+EightBit::register16_t EightBit::LittleEndianProcessor::fetchWord() noexcept {
 	intermediate().low = fetchByte();
 	intermediate().high = fetchByte();
 	return intermediate();
 }
 
-void EightBit::LittleEndianProcessor::pushWord(const register16_t value) {
+void EightBit::LittleEndianProcessor::pushWord(const register16_t value) noexcept {
 	push(value.high);
 	push(value.low);
 }
 
-EightBit::register16_t EightBit::LittleEndianProcessor::popWord() {
+EightBit::register16_t EightBit::LittleEndianProcessor::popWord() noexcept {
 	const auto low = pop();
 	const auto high = pop();
 	return { low, high };

src/Processor.cpp

@@ -7,109 +7,109 @@ EightBit::Processor::Processor(Bus& bus) noexcept
 
 EightBit::Processor::Processor(const Processor& rhs) noexcept
 : ClockedChip(rhs),
-  m_bus(rhs.m_bus) {
+  m_bus(rhs.m_bus),
+  m_opcode(rhs.m_opcode),
+  m_pc(rhs.m_pc),
+  m_intermediate(rhs.m_intermediate) {
 	RESET() = rhs.RESET();
 	INT() = rhs.INT();
-	PC() = rhs.PC();
 }
 
 DEFINE_PIN_LEVEL_CHANGERS(RESET, Processor)
 DEFINE_PIN_LEVEL_CHANGERS(INT, Processor)
 
-void EightBit::Processor::handleRESET() {
+void EightBit::Processor::handleRESET() noexcept {
 	raiseRESET();
 }
 
-void EightBit::Processor::handleINT() {
+void EightBit::Processor::handleINT() noexcept {
 	raiseINT();
 }
 
-void EightBit::Processor::memoryWrite(const register16_t address, const uint8_t data) {
+void EightBit::Processor::memoryWrite(const register16_t address, const uint8_t data) noexcept {
 	BUS().ADDRESS() = address;
 	memoryWrite(data);
 }
 
-void EightBit::Processor::memoryWrite(const register16_t address) {
+void EightBit::Processor::memoryWrite(const register16_t address) noexcept {
 	BUS().ADDRESS() = address;
 	memoryWrite();
 }
 
-void EightBit::Processor::memoryWrite(const uint8_t data) {
+void EightBit::Processor::memoryWrite(const uint8_t data) noexcept {
 	BUS().DATA() = data;
 	memoryWrite();
 }
 
-void EightBit::Processor::memoryWrite() {
+void EightBit::Processor::memoryWrite() noexcept {
 	busWrite();
 }
 
-void EightBit::Processor::busWrite() {
+void EightBit::Processor::busWrite() noexcept {
 	BUS().write();
 }
 
-uint8_t EightBit::Processor::memoryRead(const register16_t address) {
+uint8_t EightBit::Processor::memoryRead(const register16_t address) noexcept {
 	BUS().ADDRESS() = address;
 	return memoryRead();
 }
 
-uint8_t EightBit::Processor::memoryRead() {
+uint8_t EightBit::Processor::memoryRead() noexcept {
 	return busRead();
 }
 
-uint8_t EightBit::Processor::busRead() {
+uint8_t EightBit::Processor::busRead() noexcept {
 	return BUS().read();
 }
 
-EightBit::register16_t EightBit::Processor::getWordPaged(register16_t address) {
+EightBit::register16_t EightBit::Processor::getWordPaged(register16_t address) noexcept {
 	BUS().ADDRESS() = address;
 	return getWordPaged();
 }
 
-EightBit::register16_t EightBit::Processor::getWordPaged(const uint8_t page, const uint8_t offset) {
+EightBit::register16_t EightBit::Processor::getWordPaged(const uint8_t page, const uint8_t offset) noexcept {
 	BUS().ADDRESS() = { offset, page };
 	return getWordPaged();
 }
 
-void EightBit::Processor::setWordPaged(register16_t address, const register16_t value) {
+void EightBit::Processor::setWordPaged(register16_t address, const register16_t value) noexcept {
 	BUS().ADDRESS() = address;
 	setWordPaged(value);
 }
 
-void EightBit::Processor::setWordPaged(const uint8_t page, const uint8_t offset, const register16_t value) {
+void EightBit::Processor::setWordPaged(const uint8_t page, const uint8_t offset, const register16_t value) noexcept {
 	BUS().ADDRESS() = { offset, page };
 	setWordPaged(value);
 }
 
-EightBit::register16_t& EightBit::Processor::incrementPC() {
-	PC()++;
-	return PC();
+EightBit::register16_t& EightBit::Processor::incrementPC() noexcept {
+	return ++PC();
 }
 
-EightBit::register16_t& EightBit::Processor::decrementPC() {
-	PC()--;
-	return PC();
+EightBit::register16_t& EightBit::Processor::decrementPC() noexcept {
+	return --PC();
 }
 
-void EightBit::Processor::immediateAddress() {
+void EightBit::Processor::immediateAddress() noexcept {
 	BUS().ADDRESS() = PC();
 	incrementPC();
 }
 
-uint8_t EightBit::Processor::fetchByte() {
+uint8_t EightBit::Processor::fetchByte() noexcept {
 	immediateAddress();
 	return memoryRead();
 }
 
-uint8_t EightBit::Processor::fetchInstruction() {
+uint8_t EightBit::Processor::fetchInstruction() noexcept {
 	return fetchByte();
 }
 
-EightBit::register16_t EightBit::Processor::getWord(const register16_t address) {
+EightBit::register16_t EightBit::Processor::getWord(const register16_t address) noexcept {
 	BUS().ADDRESS() = address;
 	return getWord();
 }
 
-void EightBit::Processor::setWord(const register16_t address, const register16_t value) {
+void EightBit::Processor::setWord(const register16_t address, const register16_t value) noexcept {
 	BUS().ADDRESS() = address;
 	setWord(value);
 }
@@ -120,7 +120,7 @@ int EightBit::Processor::step() noexcept {
 	if (LIKELY(powered()))
 		poweredStep();
 	ExecutedInstruction.fire();
-	ASSUME(cycles() > 0);
+	// ASSUME(cycles() > 0); Not if unpowered!!
 	return cycles();
 }
 
@@ -141,15 +141,15 @@ void EightBit::Processor::jump(const register16_t destination) noexcept {
 }
 
 void EightBit::Processor::jump(const uint16_t destination) noexcept {
-	PC().word = destination;
+	PC() = destination;
 }
 
-void EightBit::Processor::call(const register16_t destination) {
+void EightBit::Processor::call(const register16_t destination) noexcept {
 	pushWord(PC());
 	jump(destination);
 }
 
-void EightBit::Processor::ret() {
+void EightBit::Processor::ret() noexcept {
 	jump(popWord());
 }
 

src/Rom.cpp

@@ -3,7 +3,7 @@
 
 #include <iostream>
 
-bool EightBit::Rom::operator==(const Rom& rhs) const {
+bool EightBit::Rom::operator==(const Rom& rhs) const noexcept {
 	return BYTES() == rhs.BYTES();
 }
 
@@ -48,10 +48,10 @@ void EightBit::Rom::poke(const uint16_t address, const uint8_t value) noexcept {
 EightBit::Rom::Rom(const size_t size) noexcept
 : m_bytes(size) {}
 
-EightBit::Rom::Rom(const Rom& rhs)
+EightBit::Rom::Rom(const Rom& rhs) noexcept
 : m_bytes(rhs.m_bytes) {}
 
-EightBit::Rom& EightBit::Rom::operator=(const Rom& rhs) {
+EightBit::Rom& EightBit::Rom::operator=(const Rom& rhs) noexcept {
 	if (this != &rhs)
 		m_bytes = rhs.m_bytes;
 	return *this;