Initial 65C02 Support

First pass at adding CMOS 65C02 support for the following instructions and addressing modes: * ORA (ZP Indirect) * AND (ZP Indirect) * EOR (ZP Indirect) * ADC (ZP Indirect) * STA (ZP Indirect) * LDA (ZP Indirect) * CMP (ZP Indirect) * SBC (ZP Indirect)
Minor whitespace cleanup
2016-06-12 18:55:09 -07:00 · 2016-06-11 11:46:31 -07:00 · 2016-03-20 11:43:42 -07:00 · 2016-03-20 17:05:48 +11:00 · 2016-03-14 20:01:12 -05:00 · 2016-01-12 08:14:38 -06:00
16 changed files with 712 additions and 185 deletions
@@ -4,7 +4,7 @@
    <groupId>com.loomcom.symon</groupId>
    <artifactId>symon</artifactId>
    <packaging>jar</packaging>
-    <version>1.2.1</version>
+    <version>1.3.0-SNAPSHOT</version>
    <name>symon</name>
    <url>http://www.loomcom.com/symon</url>
    <properties>
@@ -7,7 +7,7 @@ echo_irq: echo_irq.o
 	$(LD) -C symon.config -vm -m echo_irq.map -o echo_irq.rom echo_irq.o

 echo_irq.o:
-	$(CA) --listing -o echo_irq.o echo_irq.asm
+	$(CA) --listing echo_irq.lst -o echo_irq.o echo_irq.asm

 clean:
 	rm -f *.o *.rom *.map *.lst
@@ -1,5 +1,5 @@
 MEMORY {
-RAM1: start = $0000, size = $8000;
+RAM1: start = $0000, size = $8000 - __STACKSIZE__;
 ROM1: start = $C000, size = $3FFA, fill = yes;
 ROMV: start = $FFFA, size = $6, file = %O, fill = yes;
 }
@@ -11,6 +11,6 @@ VECTORS:  load = ROMV, type = ro;
 }

 SYMBOLS {
-__STACKSIZE__ = $0300;
+__STACKSIZE__: type = weak, value = $0300;
 }

@@ -7,7 +7,7 @@ ehbasic: ehbasic.o
 	$(LD) -C symon.config -vm -m ehbasic.map -o ehbasic.rom ehbasic.o

 ehbasic.o:
-	$(CA) --listing -o ehbasic.o min_mon.asm
+	$(CA) --listing ehbasic.lst -o ehbasic.o min_mon.asm

 clean:
 	rm -f *.o *.rom *.map *.lst
@@ -1,5 +1,5 @@
 MEMORY {
-RAM1: start = $0000, size = $8000;
+RAM1: start = $0000, size = $8000 - __STACKSIZE__;
 ROM1: start = $C000, size = $3F00, fill = yes;
 MONITOR: start = $FF00, size = $FA, fill = yes;
 ROMV: start = $FFFA, size = $6, file = %O, fill = yes;
@@ -13,6 +13,6 @@ VECTORS:  load = ROMV, type = ro;
 }

 SYMBOLS {
-__STACKSIZE__ = $0300;
+__STACKSIZE__: type = weak, value = $0300;
 }

@@ -7,7 +7,7 @@ ehbasic: ehbasic.o
 	$(LD) -C symon.config -vm -m ehbasic.map -o ehbasic.rom ehbasic.o

 ehbasic.o:
-	$(CA) --listing -o ehbasic.o min_mon.asm
+	$(CA) --listing ehbasic.lst -o ehbasic.o min_mon.asm

 clean:
 	rm -f *.o *.rom *.map *.lst
@@ -1,5 +1,5 @@
 MEMORY {
-RAM1: start = $0000, size = $8000;
+RAM1: start = $0000, size = $8000 - __STACKSIZE__;
 ROM1: start = $C000, size = $3C00, fill = yes;
 MONITOR: start = $FC00, size = $3FA, fill = yes;
 ROMV: start = $FFFA, size = $6, file = %O, fill = yes;
@@ -13,6 +13,6 @@ VECTORS:  load = ROMV, type = ro;
 }

 SYMBOLS {
-__STACKSIZE__ = $0300;
+__STACKSIZE__: type = weak, value = $0300;
 }

@@ -26,6 +26,7 @@ package com.loomcom.symon;
 import com.loomcom.symon.devices.Device;
 import com.loomcom.symon.exceptions.MemoryAccessException;
 import com.loomcom.symon.exceptions.MemoryRangeException;
+
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -42,7 +43,7 @@ public class Bus {

    // The default address at which to load programs
    public static int DEFAULT_LOAD_ADDRESS = 0x0200;
-	
+
    // By default, our bus starts at 0, and goes up to 64K
    private int startAddress = 0x0000;
    private int endAddress = 0xffff;
@@ -52,10 +53,10 @@ public class Bus {

    // Ordered sets of IO devices, associated with their priority
    private Map<Integer, SortedSet<Device>> deviceMap;
-    
+
    // an array for quick lookup of adresses, brute-force style
    private Device[] deviceAddressArray;
-    
+

    public Bus(int size) {
        this(0, size - 1);
@@ -74,30 +75,30 @@ public class Bus {
    public int endAddress() {
        return endAddress;
    }
-    
+
    private void buildDeviceAddressArray() {
        int size = (this.endAddress - this.startAddress) + 1;
        deviceAddressArray = new Device[size];
-   
+
        // getDevices() provides an OrderedSet with devices ordered by priorities
-        for(Device device : getDevices()) {
+        for (Device device : getDevices()) {
            MemoryRange range = device.getMemoryRange();
-            for(int address = range.startAddress; address <= range.endAddress; ++address) {
+            for (int address = range.startAddress; address <= range.endAddress; ++address) {
                deviceAddressArray[address - this.startAddress] = device;
            }
        }
-        
+
    }

    /**
     * Add a device to the bus.
     *
-     * @param device Device to add
+     * @param device   Device to add
     * @param priority Bus prioirity.
     * @throws MemoryRangeException
     */
    public void addDevice(Device device, int priority) throws MemoryRangeException {
-        
+
        MemoryRange range = device.getMemoryRange();

        if (range.startAddress() < this.startAddress || range.startAddress() > this.endAddress) {
@@ -114,12 +115,12 @@ public class Bus {
            deviceSet = new TreeSet<>();
            deviceMap.put(priority, deviceSet);
        }
-        
+
        device.setBus(this);
        deviceSet.add(device);
        buildDeviceAddressArray();
    }
-    
+
    /**
     * Add a device to the bus. Throws a MemoryRangeException if the device overlaps with any others.
     *
@@ -129,7 +130,7 @@ public class Bus {
    public void addDevice(Device device) throws MemoryRangeException {
        addDevice(device, 0);
    }
-    
+

    /**
     * Remove a device from the bus.
@@ -137,7 +138,7 @@ public class Bus {
     * @param device Device to remove
     */
    public void removeDevice(Device device) {
-        for(SortedSet<Device> deviceSet : deviceMap.values()) {
+        for (SortedSet<Device> deviceSet : deviceMap.values()) {
            deviceSet.remove(device);
        }
        buildDeviceAddressArray();
@@ -154,39 +155,39 @@ public class Bus {
     * device.
     */
    public boolean isComplete() {
-        if(deviceAddressArray == null) {
+        if (deviceAddressArray == null) {
            buildDeviceAddressArray();
        }
-        
-        for(int address = startAddress; address <= endAddress; ++address) {
-            if(deviceAddressArray[address - startAddress] == null) {
+
+        for (int address = startAddress; address <= endAddress; ++address) {
+            if (deviceAddressArray[address - startAddress] == null) {
                return false;
            }
        }
-        
+
        return true;
    }

    public int read(int address) throws MemoryAccessException {
        Device d = deviceAddressArray[address - this.startAddress];
-        if(d != null) {
+        if (d != null) {
            MemoryRange range = d.getMemoryRange();
            int devAddr = address - range.startAddress();
            return d.read(devAddr) & 0xff;
        }
-        
+
        throw new MemoryAccessException("Bus read failed. No device at address " + String.format("$%04X", address));
    }

    public void write(int address, int value) throws MemoryAccessException {
        Device d = deviceAddressArray[address - this.startAddress];
-        if(d != null) {
+        if (d != null) {
            MemoryRange range = d.getMemoryRange();
            int devAddr = address - range.startAddress();
            d.write(devAddr, value);
            return;
        }
-        
+
        throw new MemoryAccessException("Bus write failed. No device at address " + String.format("$%04X", address));
    }

@@ -217,17 +218,17 @@ public class Bus {
    public SortedSet<Device> getDevices() {
        // create an ordered set of devices, ordered by device priorities
        SortedSet<Device> devices = new TreeSet<>();
-        
+
        List<Integer> priorities = new ArrayList<>(deviceMap.keySet());
        Collections.sort(priorities);
-        
+
        for (int priority : priorities) {
            SortedSet<Device> deviceSet = deviceMap.get(priority);
            for (Device device : deviceSet) {
                devices.add(device);
            }
        }
-        
+
        return devices;
    }

@@ -79,7 +79,7 @@ public class Cpu implements InstructionTable {
     * Construct a new CPU.
     */
    public Cpu() {
-        this(CpuBehavior.NMOS_WITH_INDIRECT_JMP_BUG);
+        this(CpuBehavior.NMOS_6502);
    }

    public Cpu(CpuBehavior behavior) {
@@ -204,6 +204,13 @@ public class Cpu implements InstructionTable {
                    case 3: // Absolute
                        effectiveAddress = Utils.address(state.args[0], state.args[1]);
                        break;
+                    case 4: // 65C02 (Zero Page)
+                        if (behavior == CpuBehavior.CMOS_6502 ||
+                            behavior == CpuBehavior.CMOS_65816) {
+                            effectiveAddress = Utils.address(bus.read(state.args[0]),
+                                                             bus.read((state.args[0] + 1) & 0xff));
+                        }
+                        break;
                    case 5: // Zero Page,X / Zero Page,Y
                        if (state.ir == 0x96 || state.ir == 0xb6) {
                            effectiveAddress = zpyAddress(state.args[0]);
@@ -258,13 +265,11 @@ public class Cpu implements InstructionTable {

            /** Single Byte Instructions; Implied and Relative **/
            case 0x00: // BRK - Force Interrupt - Implied
-                if (!getIrqDisableFlag()) {
-                    handleIrq(state.pc + 1);
-                }
+                handleBrk(state.pc + 1);
                break;
            case 0x08: // PHP - Push Processor Status - Implied
                // Break flag is always set in the stack value.
-                stackPush(state.getStatusFlag() | 0x10); 
+                stackPush(state.getStatusFlag() | 0x10);
                break;
            case 0x10: // BPL - Branch if Positive - Relative
                if (!getNegativeFlag()) {
@@ -400,11 +405,12 @@ public class Cpu implements InstructionTable {
            case 0x4c: // JMP - Absolute
                state.pc = Utils.address(state.args[0], state.args[1]);
                break;
+            // TODO: 65C02 instruction 0x7C, JMP (Indirect,X)
            case 0x6c: // JMP - Indirect
                lo = Utils.address(state.args[0], state.args[1]); // Address of low byte

                if (state.args[0] == 0xff &&
-                    (behavior == CpuBehavior.NMOS_WITH_INDIRECT_JMP_BUG ||
+                    (behavior == CpuBehavior.NMOS_6502 ||
                     behavior == CpuBehavior.NMOS_WITH_ROR_BUG)) {
                    hi = Utils.address(0x00, state.args[1]);
                } else {
@@ -424,13 +430,20 @@ public class Cpu implements InstructionTable {
                 * (http://www.obelisk.demon.co.uk/6502/reference.html#JMP)
                 */
                break;
-
+            case 0x7C: // 65C02 JMP - Absolute,X
+                state.pc = (Utils.address(state.args[0], state.args[1]) + state.x) & 0xffff;
+                break;

            /** ORA - Logical Inclusive Or ******************************************/
            case 0x09: // #Immediate
                state.a |= state.args[0];
                setArithmeticFlags(state.a);
                break;
+            case 0x12: // 65C02 ORA (ZP)
+                if (behavior == CpuBehavior.NMOS_6502 ||
+                    behavior == CpuBehavior.NMOS_WITH_ROR_BUG) {
+                    break;
+                }
            case 0x01: // (Zero Page,X)
            case 0x05: // Zero Page
            case 0x0d: // Absolute
@@ -473,6 +486,11 @@ public class Cpu implements InstructionTable {
                state.a &= state.args[0];
                setArithmeticFlags(state.a);
                break;
+            case 0x32: // 65C02 AND (ZP)
+                if (behavior == CpuBehavior.NMOS_6502 ||
+                    behavior == CpuBehavior.NMOS_WITH_ROR_BUG) {
+                    break;
+                }
            case 0x21: // (Zero Page,X)
            case 0x25: // Zero Page
            case 0x2d: // Absolute
@@ -505,6 +523,11 @@ public class Cpu implements InstructionTable {
                state.a ^= state.args[0];
                setArithmeticFlags(state.a);
                break;
+            case 0x52: // 65C02 EOR (ZP)
+                if (behavior == CpuBehavior.NMOS_6502 ||
+                    behavior == CpuBehavior.NMOS_WITH_ROR_BUG) {
+                    break;
+                }
            case 0x41: // (Zero Page,X)
            case 0x45: // Zero Page
            case 0x4d: // Absolute
@@ -540,6 +563,11 @@ public class Cpu implements InstructionTable {
                    state.a = adc(state.a, state.args[0]);
                }
                break;
+            case 0x72: // 65C02 ADC (ZP)
+                if (behavior == CpuBehavior.NMOS_6502 ||
+                    behavior == CpuBehavior.NMOS_WITH_ROR_BUG) {
+                    break;
+                }
            case 0x61: // (Zero Page,X)
            case 0x65: // Zero Page
            case 0x6d: // Absolute
@@ -571,6 +599,11 @@ public class Cpu implements InstructionTable {


            /** STA - Store Accumulator *********************************************/
+            case 0x92: // 65C02 STA (ZP)
+                if (behavior == CpuBehavior.NMOS_6502 ||
+                    behavior == CpuBehavior.NMOS_WITH_ROR_BUG) {
+                    break;
+                }
            case 0x81: // (Zero Page,X)
            case 0x85: // Zero Page
            case 0x8d: // Absolute
@@ -631,6 +664,11 @@ public class Cpu implements InstructionTable {
                state.a = state.args[0];
                setArithmeticFlags(state.a);
                break;
+            case 0xb2: // 65C02 LDA (ZP)
+                if (behavior == CpuBehavior.NMOS_6502 ||
+                    behavior == CpuBehavior.NMOS_WITH_ROR_BUG) {
+                    break;
+                }
            case 0xa1: // (Zero Page,X)
            case 0xa5: // Zero Page
            case 0xad: // Absolute
@@ -657,6 +695,11 @@ public class Cpu implements InstructionTable {
            case 0xc9: // #Immediate
                cmp(state.a, state.args[0]);
                break;
+            case 0xd2: // 65C02 CMP (ZP)
+                if (behavior == CpuBehavior.NMOS_6502 ||
+                    behavior == CpuBehavior.NMOS_WITH_ROR_BUG) {
+                    break;
+                }
            case 0xc1: // (Zero Page,X)
            case 0xc5: // Zero Page
            case 0xcd: // Absolute
@@ -697,6 +740,11 @@ public class Cpu implements InstructionTable {
                    state.a = sbc(state.a, state.args[0]);
                }
                break;
+            case 0xf2: // 65C02 SBC (ZP)
+                if (behavior == CpuBehavior.NMOS_6502 ||
+                    behavior == CpuBehavior.NMOS_WITH_ROR_BUG) {
+                    break;
+                }
            case 0xe1: // (Zero Page,X)
            case 0xe5: // Zero Page
            case 0xed: // Absolute
@@ -744,13 +792,18 @@ public class Cpu implements InstructionTable {
        }
    }

+    private void handleBrk(int returnPc) throws MemoryAccessException {
+        handleInterrupt(returnPc, IRQ_VECTOR_L, IRQ_VECTOR_H, true);
+        clearIrq();
+    }
+
    private void handleIrq(int returnPc) throws MemoryAccessException {
-        handleInterrupt(returnPc, IRQ_VECTOR_L, IRQ_VECTOR_H);
+        handleInterrupt(returnPc, IRQ_VECTOR_L, IRQ_VECTOR_H, false);
        clearIrq();
    }

    private void handleNmi() throws MemoryAccessException {
-        handleInterrupt(state.pc, NMI_VECTOR_L, NMI_VECTOR_H);
+        handleInterrupt(state.pc, NMI_VECTOR_L, NMI_VECTOR_H, false);
        clearNmi();
    }

@@ -759,9 +812,19 @@ public class Cpu implements InstructionTable {
     *
     * @throws MemoryAccessException
     */
-    private void handleInterrupt(int returnPc, int vectorLow, int vectorHigh) throws MemoryAccessException {
-        // Set the break flag before pushing.
-        setBreakFlag();
+    private void handleInterrupt(int returnPc, int vectorLow, int vectorHigh, boolean isBreak) throws MemoryAccessException {
+
+        if (isBreak)
+        {
+            // Set the break flag before pushing.
+            setBreakFlag();
+        }
+        else
+        {
+            // IRQ & NMI clear break flag
+            clearBreakFlag();
+        }
+
        // Push program counter + 1 onto the stack
        stackPush((returnPc >> 8) & 0xff); // PC high byte
        stackPush(returnPc & 0xff);        // PC low byte
@@ -1321,6 +1384,13 @@ public class Cpu implements InstructionTable {
        return (zp + state.x) & 0xff;
    }

+    /**
+     * Given a single byte, compute the Zero Page,Y offset address.
+     */
+    int zpyAddress(int zp) {
+        return (zp + state.y) & 0xff;
+    }
+
    /**
     * Given a single byte, compute the offset address.
     */
@@ -1329,21 +1399,21 @@ public class Cpu implements InstructionTable {
        return (state.pc + (byte) offset) & 0xffff;
    }

-    /**
-     * Given a single byte, compute the Zero Page,Y offset address.
-     */
-    int zpyAddress(int zp) {
-        return (zp + state.y) & 0xff;
-    }
-
    /*
     * Perform a busy-loop until the instruction should complete on the wall clock
     */
    private void delayLoop(int opcode) {
-        int clockSteps = Cpu.instructionClocks[0xff & opcode];
+        final int clockSteps;
+
+        if (behavior == CpuBehavior.NMOS_WITH_ROR_BUG ||
+            behavior == CpuBehavior.NMOS_6502) {
+            clockSteps = Cpu.instructionClocksNmos[0xff & opcode];
+        } else {
+            clockSteps = Cpu.instructionClocksCmos[0xff & opcode];
+        }

        if (clockSteps == 0) {
-            logger.warn("Opcode {} has clock step of 0!", opcode);
+            logger.warn("Opcode {} has clock step of 0!", String.format("0x%02x", opcode));
            return;
        }

@@ -46,20 +46,17 @@ public interface InstructionTable {
         *
         * NB: Does NOT implement "unimplemented" NMOS instructions.
         */
-        NMOS_WITH_INDIRECT_JMP_BUG,
-
-        /**
-         * Emulate an NMOS 6502 without the indirect JMP bug. This type of 6502
-         * does not actually exist in the wild.
-         *
-         * NB: Does NOT implement "unimplemented" NMOS instructions.
-         */
-        NMOS_WITHOUT_INDIRECT_JMP_BUG,
+        NMOS_6502,

        /**
         * Emulate a CMOS 65C02, with all CMOS instructions and addressing modes.
         */
-        CMOS
+        CMOS_6502,
+
+        /**
+         * Emulate a CMOS 65C816.
+         */
+        CMOS_65816
    }

    /**
@@ -128,19 +125,25 @@ public interface InstructionTable {

        ZPG {
            public String toString() {
-                return "Zeropage";
+                return "Zero Page";
            }
        },

        ZPX {
            public String toString() {
-                return "Zeropage, X-indexed";
+                return "Zero Page, X-indexed";
            }
        },

        ZPY {
            public String toString() {
-                return "Zeropage, Y-indexed";
+                return "Zero Page, Y-indexed";
+            }
+        },
+
+        ZPI {
+            public String toString() {
+                return "Zero Page Indirect";
            }
        },

@@ -154,52 +157,55 @@ public interface InstructionTable {
    // 6502 opcodes.  No 65C02 opcodes implemented.

    /**
-     * Instruction opcode names.
+     * Instruction opcode names. This lists all opcodes for
+     * NMOS 6502, CMOS 65C02, and CMOS 65C816
     */
    String[] opcodeNames = {
-        "BRK", "ORA",  null,  null,  null, "ORA", "ASL",  null,
-        "PHP", "ORA", "ASL",  null,  null, "ORA", "ASL",  null,
-        "BPL", "ORA",  null,  null,  null, "ORA", "ASL",  null,
-        "CLC", "ORA",  null,  null,  null, "ORA", "ASL",  null,
-        "JSR", "AND",  null,  null, "BIT", "AND", "ROL",  null,
-        "PLP", "AND", "ROL",  null, "BIT", "AND", "ROL",  null,
-        "BMI", "AND",  null,  null,  null, "AND", "ROL",  null,
-        "SEC", "AND",  null,  null,  null, "AND", "ROL",  null,
-        "RTI", "EOR",  null,  null,  null, "EOR", "LSR",  null,
-        "PHA", "EOR", "LSR",  null, "JMP", "EOR", "LSR",  null,
-        "BVC", "EOR",  null,  null,  null, "EOR", "LSR",  null,
-        "CLI", "EOR",  null,  null,  null, "EOR", "LSR",  null,
-        "RTS", "ADC",  null,  null,  null, "ADC", "ROR",  null,
-        "PLA", "ADC", "ROR",  null, "JMP", "ADC", "ROR",  null,
-        "BVS", "ADC",  null,  null,  null, "ADC", "ROR",  null,
-        "SEI", "ADC",  null,  null,  null, "ADC", "ROR",  null,
-        "BCS", "STA",  null,  null, "STY", "STA", "STX",  null,
-        "DEY",  null, "TXA",  null, "STY", "STA", "STX",  null,
-        "BCC", "STA",  null,  null, "STY", "STA", "STX",  null,
-        "TYA", "STA", "TXS",  null,  null, "STA",  null,  null,
-        "LDY", "LDA", "LDX",  null, "LDY", "LDA", "LDX",  null,
-        "TAY", "LDA", "TAX",  null, "LDY", "LDA", "LDX",  null,
-        "BCS", "LDA",  null,  null, "LDY", "LDA", "LDX",  null,
-        "CLV", "LDA", "TSX",  null, "LDY", "LDA", "LDX",  null,
-        "CPY", "CMP",  null,  null, "CPY", "CMP", "DEC",  null,
-        "INY", "CMP", "DEX",  null, "CPY", "CMP", "DEC",  null,
-        "BNE", "CMP",  null,  null,  null, "CMP", "DEC",  null,
-        "CLD", "CMP",  null,  null,  null, "CMP", "DEC",  null,
-        "CPX", "SBC",  null,  null, "CPX", "SBC", "INC",  null,
-        "INX", "SBC", "NOP",  null, "CPX", "SBC", "INC",  null,
-        "BEQ", "SBC",  null,  null,  null, "SBC", "INC",  null,
-        "SED", "SBC",  null,  null,  null, "SBC", "INC",  null
+        "BRK", "ORA",  null,  null,  null, "ORA", "ASL",  null,  // 0x00-0x07
+        "PHP", "ORA", "ASL",  null,  null, "ORA", "ASL",  null,  // 0x08-0x0f
+        "BPL", "ORA", "ORA",  null,  null, "ORA", "ASL",  null,  // 0x10-0x17
+        "CLC", "ORA",  null,  null,  null, "ORA", "ASL",  null,  // 0x18-0x1f
+        "JSR", "AND",  null,  null, "BIT", "AND", "ROL",  null,  // 0x20-0x27
+        "PLP", "AND", "ROL",  null, "BIT", "AND", "ROL",  null,  // 0x28-0x2f
+        "BMI", "AND", "AND",  null,  null, "AND", "ROL",  null,  // 0x30-0x37
+        "SEC", "AND",  null,  null,  null, "AND", "ROL",  null,  // 0x38-0x3f
+        "RTI", "EOR",  null,  null,  null, "EOR", "LSR",  null,  // 0x40-0x47
+        "PHA", "EOR", "LSR",  null, "JMP", "EOR", "LSR",  null,  // 0x48-0x4f
+        "BVC", "EOR", "EOR",  null,  null, "EOR", "LSR",  null,  // 0x50-0x57
+        "CLI", "EOR",  null,  null,  null, "EOR", "LSR",  null,  // 0x58-0x5f
+        "RTS", "ADC",  null,  null,  null, "ADC", "ROR",  null,  // 0x60-0x67
+        "PLA", "ADC", "ROR",  null, "JMP", "ADC", "ROR",  null,  // 0x68-0x6f
+        "BVS", "ADC", "ADC",  null,  null, "ADC", "ROR",  null,  // 0x70-0x77
+        "SEI", "ADC",  null,  null, "JMP", "ADC", "ROR",  null,  // 0x78-0x7f
+        "BCS", "STA",  null,  null, "STY", "STA", "STX",  null,  // 0x80-0x87
+        "DEY",  null, "TXA",  null, "STY", "STA", "STX",  null,  // 0x88-0x8f
+        "BCC", "STA", "STA",  null, "STY", "STA", "STX",  null,  // 0x90-0x97
+        "TYA", "STA", "TXS",  null,  null, "STA",  null,  null,  // 0x98-0x9f
+        "LDY", "LDA", "LDX",  null, "LDY", "LDA", "LDX",  null,  // 0xa0-0xa7
+        "TAY", "LDA", "TAX",  null, "LDY", "LDA", "LDX",  null,  // 0xa8-0xaf
+        "BCS", "LDA", "LDA",  null, "LDY", "LDA", "LDX",  null,  // 0xb0-0xb7
+        "CLV", "LDA", "TSX",  null, "LDY", "LDA", "LDX",  null,  // 0xb8-0xbf
+        "CPY", "CMP",  null,  null, "CPY", "CMP", "DEC",  null,  // 0xc0-0xc7
+        "INY", "CMP", "DEX",  null, "CPY", "CMP", "DEC",  null,  // 0xc8-0xcf
+        "BNE", "CMP", "CMP",  null,  null, "CMP", "DEC",  null,  // 0xd0-0xd7
+        "CLD", "CMP",  null,  null,  null, "CMP", "DEC",  null,  // 0xd8-0xdf
+        "CPX", "SBC",  null,  null, "CPX", "SBC", "INC",  null,  // 0xe0-0xe7
+        "INX", "SBC", "NOP",  null, "CPX", "SBC", "INC",  null,  // 0xe8-0xef
+        "BEQ", "SBC", "SBC",  null,  null, "SBC", "INC",  null,  // 0xf0-0xf7
+        "SED", "SBC",  null,  null,  null, "SBC", "INC",  null   // 0xf8-0xff
    };

    /**
-     * Instruction addressing modes.
+     * Instruction addressing modes. This table includes sizes
+     * for all instructions for NMOS 6502, CMOS 65C02,
+     * and CMOS 65C816
     */
    Mode[] instructionModes = {
        Mode.IMP, Mode.XIN, Mode.NUL, Mode.NUL,   // 0x00-0x03
        Mode.NUL, Mode.ZPG, Mode.ZPG, Mode.NUL,   // 0x04-0x07
        Mode.IMP, Mode.IMM, Mode.ACC, Mode.NUL,   // 0x08-0x0b
        Mode.NUL, Mode.ABS, Mode.ABS, Mode.NUL,   // 0x0c-0x0f
-        Mode.REL, Mode.INY, Mode.NUL, Mode.NUL,   // 0x10-0x13
+        Mode.REL, Mode.INY, Mode.ZPI, Mode.NUL,   // 0x10-0x13
        Mode.NUL, Mode.ZPX, Mode.ZPX, Mode.NUL,   // 0x14-0x17
        Mode.IMP, Mode.ABY, Mode.NUL, Mode.NUL,   // 0x18-0x1b
        Mode.NUL, Mode.ABX, Mode.ABX, Mode.NUL,   // 0x1c-0x1f
@@ -207,7 +213,7 @@ public interface InstructionTable {
        Mode.ZPG, Mode.ZPG, Mode.ZPG, Mode.NUL,   // 0x24-0x27
        Mode.IMP, Mode.IMM, Mode.ACC, Mode.NUL,   // 0x28-0x2b
        Mode.ABS, Mode.ABS, Mode.ABS, Mode.NUL,   // 0x2c-0x2f
-        Mode.REL, Mode.INY, Mode.NUL, Mode.NUL,   // 0x30-0x33
+        Mode.REL, Mode.INY, Mode.ZPI, Mode.NUL,   // 0x30-0x33
        Mode.NUL, Mode.ZPX, Mode.ZPX, Mode.NUL,   // 0x34-0x37
        Mode.IMP, Mode.ABY, Mode.NUL, Mode.NUL,   // 0x38-0x3b
        Mode.NUL, Mode.ABX, Mode.ABX, Mode.NUL,   // 0x3c-0x3f
@@ -215,7 +221,7 @@ public interface InstructionTable {
        Mode.NUL, Mode.ZPG, Mode.ZPG, Mode.NUL,   // 0x44-0x47
        Mode.IMP, Mode.IMM, Mode.ACC, Mode.NUL,   // 0x48-0x4b
        Mode.ABS, Mode.ABS, Mode.ABS, Mode.NUL,   // 0x4c-0x4f
-        Mode.REL, Mode.INY, Mode.NUL, Mode.NUL,   // 0x50-0x53
+        Mode.REL, Mode.INY, Mode.ZPI, Mode.NUL,   // 0x50-0x53
        Mode.NUL, Mode.ZPX, Mode.ZPX, Mode.NUL,   // 0x54-0x57
        Mode.IMP, Mode.ABY, Mode.NUL, Mode.NUL,   // 0x58-0x5b
        Mode.NUL, Mode.ABX, Mode.ABX, Mode.NUL,   // 0x5c-0x5f
@@ -223,15 +229,15 @@ public interface InstructionTable {
        Mode.NUL, Mode.ZPG, Mode.ZPG, Mode.NUL,   // 0x64-0x67
        Mode.IMP, Mode.IMM, Mode.ACC, Mode.NUL,   // 0x68-0x6b
        Mode.IND, Mode.ABS, Mode.ABS, Mode.NUL,   // 0x6c-0x6f
-        Mode.REL, Mode.INY, Mode.NUL, Mode.NUL,   // 0x70-0x73
+        Mode.REL, Mode.INY, Mode.ZPI, Mode.NUL,   // 0x70-0x73
        Mode.NUL, Mode.ZPX, Mode.ZPX, Mode.NUL,   // 0x74-0x77
        Mode.IMP, Mode.ABY, Mode.NUL, Mode.NUL,   // 0x78-0x7b
-        Mode.NUL, Mode.ABX, Mode.ABX, Mode.NUL,   // 0x7c-0x7f
+        Mode.ABX, Mode.ABX, Mode.ABX, Mode.NUL,   // 0x7c-0x7f
        Mode.REL, Mode.XIN, Mode.NUL, Mode.NUL,   // 0x80-0x83
        Mode.ZPG, Mode.ZPG, Mode.ZPG, Mode.NUL,   // 0x84-0x87
        Mode.IMP, Mode.NUL, Mode.IMP, Mode.NUL,   // 0x88-0x8b
        Mode.ABS, Mode.ABS, Mode.ABS, Mode.NUL,   // 0x8c-0x8f
-        Mode.REL, Mode.INY, Mode.NUL, Mode.NUL,   // 0x90-0x93
+        Mode.REL, Mode.INY, Mode.ZPI, Mode.NUL,   // 0x90-0x93
        Mode.ZPX, Mode.ZPX, Mode.ZPY, Mode.NUL,   // 0x94-0x97
        Mode.IMP, Mode.ABY, Mode.IMP, Mode.NUL,   // 0x98-0x9b
        Mode.NUL, Mode.ABX, Mode.NUL, Mode.NUL,   // 0x9c-0x9f
@@ -239,7 +245,7 @@ public interface InstructionTable {
        Mode.ZPG, Mode.ZPG, Mode.ZPG, Mode.NUL,   // 0xa4-0xa7
        Mode.IMP, Mode.IMM, Mode.IMP, Mode.NUL,   // 0xa8-0xab
        Mode.ABS, Mode.ABS, Mode.ABS, Mode.NUL,   // 0xac-0xaf
-        Mode.REL, Mode.INY, Mode.NUL, Mode.NUL,   // 0xb0-0xb3
+        Mode.REL, Mode.INY, Mode.ZPI, Mode.NUL,   // 0xb0-0xb3
        Mode.ZPX, Mode.ZPX, Mode.ZPY, Mode.NUL,   // 0xb4-0xb7
        Mode.IMP, Mode.ABY, Mode.IMP, Mode.NUL,   // 0xb8-0xbb
        Mode.ABX, Mode.ABX, Mode.ABY, Mode.NUL,   // 0xbc-0xbf
@@ -247,7 +253,7 @@ public interface InstructionTable {
        Mode.ZPG, Mode.ZPG, Mode.ZPG, Mode.NUL,   // 0xc4-0xc7
        Mode.IMP, Mode.IMM, Mode.IMP, Mode.NUL,   // 0xc8-0xcb
        Mode.ABS, Mode.ABS, Mode.ABS, Mode.NUL,   // 0xcc-0xcf
-        Mode.REL, Mode.INY, Mode.NUL, Mode.NUL,   // 0xd0-0xd3
+        Mode.REL, Mode.INY, Mode.ZPI, Mode.NUL,   // 0xd0-0xd3
        Mode.NUL, Mode.ZPX, Mode.ZPX, Mode.NUL,   // 0xd4-0xd7
        Mode.IMP, Mode.ABY, Mode.NUL, Mode.NUL,   // 0xd8-0xdb
        Mode.NUL, Mode.ABX, Mode.ABX, Mode.NUL,   // 0xdc-0xdf
@@ -255,7 +261,7 @@ public interface InstructionTable {
        Mode.ZPG, Mode.ZPG, Mode.ZPG, Mode.NUL,   // 0xe4-0xe7
        Mode.IMP, Mode.IMM, Mode.IMP, Mode.NUL,   // 0xe8-0xeb
        Mode.ABS, Mode.ABS, Mode.ABS, Mode.NUL,   // 0xec-0xef
-        Mode.REL, Mode.INY, Mode.NUL, Mode.NUL,   // 0xf0-0xf3
+        Mode.REL, Mode.INY, Mode.ZPI, Mode.NUL,   // 0xf0-0xf3
        Mode.NUL, Mode.ZPX, Mode.ZPX, Mode.NUL,   // 0xf4-0xf7
        Mode.IMP, Mode.ABY, Mode.NUL, Mode.NUL,   // 0xf8-0xfb
        Mode.NUL, Mode.ABX, Mode.ABX, Mode.NUL    // 0xfc-0xff
@@ -263,47 +269,73 @@ public interface InstructionTable {


    /**
-     * Size, in bytes, required for each instruction.
+     * Size, in bytes, required for each instruction. This table
+     * includes sizes for all instructions for NMOS 6502, CMOS 65C02,
+     * and CMOS 65C816
     */
    int[] instructionSizes = {
-        1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 0, 3, 3, 0,
-        2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,
-        3, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,
-        2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,
-        1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,
-        2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,
-        1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,
-        2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,
-        2, 2, 0, 0, 2, 2, 2, 0, 1, 0, 1, 0, 3, 3, 3, 0,
-        2, 2, 0, 0, 2, 2, 2, 0, 1, 3, 1, 0, 0, 3, 0, 0,
-        2, 2, 2, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,
-        2, 2, 0, 0, 2, 2, 2, 0, 1, 3, 1, 0, 3, 3, 3, 0,
-        2, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,
-        2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,
-        2, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,
-        2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0
+        1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 0, 3, 3, 0,   // 0x00-0x0f
+        2, 2, 2, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,   // 0x10-0x1f
+        3, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,   // 0x20-0x2f
+        2, 2, 2, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,   // 0x30-0x3f
+        1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,   // 0x40-0x4f
+        2, 2, 2, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,   // 0x50-0x5f
+        1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,   // 0x60-0x6f
+        2, 2, 2, 0, 0, 2, 2, 0, 1, 3, 0, 0, 3, 3, 3, 0,   // 0x70-0x7f
+        2, 2, 0, 0, 2, 2, 2, 0, 1, 0, 1, 0, 3, 3, 3, 0,   // 0x80-0x8f
+        2, 2, 2, 0, 2, 2, 2, 0, 1, 3, 1, 0, 0, 3, 0, 0,   // 0x90-0x9f
+        2, 2, 2, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,   // 0xa0-0xaf
+        2, 2, 2, 0, 2, 2, 2, 0, 1, 3, 1, 0, 3, 3, 3, 0,   // 0xb0-0xbf
+        2, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,   // 0xc0-0xcf
+        2, 2, 2, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,   // 0xd0-0xdf
+        2, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,   // 0xe0-0xef
+        2, 2, 2, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0    // 0xf0-0xff
    };

    /**
-     * Number of clock cycles required for each instruction
+     * Number of clock cycles required for each instruction when
+     * in NMOS mode.
     */
-    int[] instructionClocks = {
-        7, 6, 0, 0, 0, 3, 5, 0, 3, 2, 2, 0, 0, 4, 6, 0,
-        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,
-        6, 6, 0, 0, 3, 3, 5, 0, 4, 2, 2, 0, 4, 4, 6, 0,
-        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,
-        6, 6, 0, 0, 0, 3, 5, 0, 3, 2, 2, 0, 3, 4, 6, 0,
-        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,
-        6, 6, 0, 0, 0, 3, 5, 0, 4, 2, 2, 0, 5, 4, 6, 0,
-        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,
-        2, 6, 0, 0, 3, 3, 3, 0, 2, 0, 2, 0, 4, 4, 4, 0,
-        2, 6, 0, 0, 4, 4, 4, 0, 2, 5, 2, 0, 0, 5, 0, 0,
-        2, 6, 2, 0, 3, 3, 3, 0, 2, 2, 2, 0, 4, 4, 4, 0,
-        2, 5, 0, 0, 4, 4, 4, 0, 2, 4, 2, 0, 4, 4, 4, 0,
-        2, 6, 0, 0, 3, 3, 5, 0, 2, 2, 2, 0, 4, 4, 6, 0,
-        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,
-        2, 6, 0, 0, 3, 3, 5, 0, 2, 2, 2, 0, 4, 4, 6, 0,
-        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0
+    int[] instructionClocksNmos = {
+        7, 6, 0, 0, 0, 3, 5, 0, 3, 2, 2, 0, 0, 4, 6, 0,   // 0x00-0x0f
+        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,   // 0x10-0x1f
+        6, 6, 0, 0, 3, 3, 5, 0, 4, 2, 2, 0, 4, 4, 6, 0,   // 0x20-0x2f
+        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,   // 0x30-0x3f
+        6, 6, 0, 0, 0, 3, 5, 0, 3, 2, 2, 0, 3, 4, 6, 0,   // 0x40-0x4f
+        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,   // 0x50-0x5f
+        6, 6, 0, 0, 0, 3, 5, 0, 4, 2, 2, 0, 5, 4, 6, 0,   // 0x60-0x6f
+        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,   // 0x70-0x7f
+        2, 6, 0, 0, 3, 3, 3, 0, 2, 0, 2, 0, 4, 4, 4, 0,   // 0x80-0x8f
+        2, 6, 0, 0, 4, 4, 4, 0, 2, 5, 2, 0, 0, 5, 0, 0,   // 0x90-0x9f
+        2, 6, 2, 0, 3, 3, 3, 0, 2, 2, 2, 0, 4, 4, 4, 0,   // 0xa0-0xaf
+        2, 5, 0, 0, 4, 4, 4, 0, 2, 4, 2, 0, 4, 4, 4, 0,   // 0xb0-0xbf
+        2, 6, 0, 0, 3, 3, 5, 0, 2, 2, 2, 0, 4, 4, 6, 0,   // 0xc0-0xcf
+        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,   // 0xd0-0xdf
+        2, 6, 0, 0, 3, 3, 5, 0, 2, 2, 2, 0, 4, 4, 6, 0,   // 0xe0-0xef
+        2, 5, 0, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0    // 0xf0-0xff
+    };
+
+    /**
+     * Number of clock cycles required for each instruction when
+     * in CMOS mode
+     */
+    int[] instructionClocksCmos = {
+        7, 6, 0, 0, 0, 3, 5, 0, 3, 2, 2, 0, 0, 4, 6, 0,   // 0x00-0x0f
+        2, 5, 5, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,   // 0x10-0x1f
+        6, 6, 0, 0, 3, 3, 5, 0, 4, 2, 2, 0, 4, 4, 6, 0,   // 0x20-0x2f
+        2, 5, 5, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,   // 0x30-0x3f
+        6, 6, 0, 0, 0, 3, 5, 0, 3, 2, 2, 0, 3, 4, 6, 0,   // 0x40-0x4f
+        2, 5, 5, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,   // 0x50-0x5f
+        6, 6, 0, 0, 0, 3, 5, 0, 4, 2, 2, 0, 5, 4, 6, 0,   // 0x60-0x6f
+        2, 5, 5, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,   // 0x70-0x7f
+        2, 6, 0, 0, 3, 3, 3, 0, 2, 0, 2, 0, 4, 4, 4, 0,   // 0x80-0x8f
+        2, 6, 5, 0, 4, 4, 4, 0, 2, 5, 2, 0, 0, 5, 0, 0,   // 0x90-0x9f
+        2, 6, 2, 0, 3, 3, 3, 0, 2, 2, 2, 0, 4, 4, 4, 0,   // 0xa0-0xaf
+        2, 5, 5, 0, 4, 4, 4, 0, 2, 4, 2, 0, 4, 4, 4, 0,   // 0xb0-0xbf
+        2, 6, 0, 0, 3, 3, 5, 0, 2, 2, 2, 0, 4, 4, 6, 0,   // 0xc0-0xcf
+        2, 5, 5, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0,   // 0xd0-0xdf
+        2, 6, 0, 0, 3, 3, 5, 0, 2, 2, 2, 0, 4, 4, 6, 0,   // 0xe0-0xef
+        2, 5, 5, 0, 0, 4, 6, 0, 2, 4, 0, 0, 0, 4, 7, 0    // 0xf0-0xff
    };

 }
@@ -117,9 +117,22 @@ public class CpuImpliedModeTest {
    }

    @Test
-    public void test_BRK_HonorsIrqDisableFlag() throws MemoryAccessException {
+    public void test_BRK_IgnoresIrqDisableFlag() throws MemoryAccessException {
        cpu.setIrqDisableFlag();

+        cpu.setCarryFlag();
+        cpu.setOverflowFlag();
+        assertEquals(0x20 | Cpu.P_CARRY | Cpu.P_OVERFLOW | Cpu.P_IRQ_DISABLE,
+                     cpu.getProcessorStatus());
+        assertEquals(0x00, cpu.stackPeek());
+        assertFalse(cpu.getBreakFlag());
+        assertEquals(0x0200, cpu.getProgramCounter());
+        assertEquals(0xff, cpu.getStackPointer());
+        
+        // Set the IRQ vector
+        bus.write(0xffff, 0x12);
+        bus.write(0xfffe, 0x34);
+
        bus.loadProgram(0xea,
                        0xea,
                        0xea,
@@ -131,23 +144,26 @@ public class CpuImpliedModeTest {

        assertEquals(0x203, cpu.getProgramCounter());

-        // Triggers the BRK, which should do nothing because
-        // of the Interrupt Disable flag
+        // Triggers the BRK
        cpu.step();

-        // Reset to original contents of PC
-        assertEquals(0x0204, cpu.getProgramCounter());
-        // Empty stack
-        assertEquals(0xff, cpu.getStackPointer());

-        cpu.step(2); // Two more NOPs
+        // Was at PC = 0x204.  PC+1 should now be on the stack
+        assertEquals(0x02, bus.read(0x1ff)); // PC high byte
+        assertEquals(0x05, bus.read(0x1fe)); // PC low byte
+        assertEquals(0x20 | Cpu.P_CARRY | Cpu.P_OVERFLOW | Cpu.P_BREAK | Cpu.P_IRQ_DISABLE,
+                     bus.read(0x1fd));       // Processor Status, with B set

-        // Reset to original contents of PC
-        assertEquals(0x0206, cpu.getProgramCounter());
-        // Empty stack
-        assertEquals(0xff, cpu.getStackPointer());
+        // Interrupt vector held 0x1234, so we should be there.
+        assertEquals(0x1234, cpu.getProgramCounter());
+        assertEquals(0xfc, cpu.getStackPointer());
+
+        // B and I flags should have been set on P
+        assertEquals(0x20 | Cpu.P_CARRY | Cpu.P_OVERFLOW | Cpu.P_BREAK | Cpu.P_IRQ_DISABLE,
+                     cpu.getProcessorStatus());
    }

+
    /* CLC - Clear Carry Flag - $18 */
    @Test
    public void test_CLC() throws MemoryAccessException {
@@ -25,18 +25,10 @@ public class CpuIndirectIndexedModeTest {
        bus.write(0xfffd, (Bus.DEFAULT_LOAD_ADDRESS & 0xff00) >>> 8);

        cpu.reset();
-        // Assert initial state
-        assertEquals(0, cpu.getAccumulator());
-        assertEquals(0, cpu.getXRegister());
-        assertEquals(0, cpu.getYRegister());
-        assertEquals(0x200, cpu.getProgramCounter());
-        assertEquals(0xff, cpu.getStackPointer());
-        assertEquals(0x20, cpu.getProcessorStatus());
    }

    @Test
    public void test_LDA() throws Exception {
-        assertEquals(cpu.toString(), 0x00, cpu.getAccumulator());
        bus.write(0x0014, 0x00);
        bus.write(0x0015, 0xd8);
        bus.write(0xd828, 0x03);
@@ -3,15 +3,19 @@ package com.loomcom.symon;
 import com.loomcom.symon.devices.Memory;
 import com.loomcom.symon.exceptions.MemoryAccessException;

-import junit.framework.TestCase;
+import org.junit.Before;
+import org.junit.Test;

-public class CpuIndirectModeTest extends TestCase {
+import static org.junit.Assert.assertEquals;
+
+public class CpuIndirectModeTest {

    protected Cpu    cpu;
    protected Bus    bus;
    protected Memory mem;

-    protected void setUp() throws Exception {
+    @Before
+    public void setUp() throws Exception {
        this.cpu = new Cpu();
        this.bus = new Bus(0x0000, 0xffff);
        this.mem = new Memory(0x0000, 0xffff);
@@ -41,6 +45,7 @@ public class CpuIndirectModeTest extends TestCase {

    /* JMP - Jump - $6c */

+    @Test
    public void test_JMP_notOnPageBoundary() throws MemoryAccessException {
        bus.write(0x3400, 0x00);
        bus.write(0x3401, 0x54);
@@ -51,6 +56,7 @@ public class CpuIndirectModeTest extends TestCase {
        assertEquals(0x20, cpu.getProcessorStatus());
    }

+    @Test
    public void test_JMP_with_ROR_Bug() throws MemoryAccessException {
        cpu.setBehavior(Cpu.CpuBehavior.NMOS_WITH_ROR_BUG);
        bus.write(0x3400, 0x22);
@@ -63,8 +69,9 @@ public class CpuIndirectModeTest extends TestCase {
        assertEquals(0x20, cpu.getProcessorStatus());
    }

+    @Test
    public void test_JMP_withIndirectBug() throws MemoryAccessException {
-        cpu.setBehavior(Cpu.CpuBehavior.NMOS_WITH_INDIRECT_JMP_BUG);
+        cpu.setBehavior(Cpu.CpuBehavior.NMOS_6502);
        bus.write(0x3400, 0x22);
        bus.write(0x34ff, 0x00);
        bus.write(0x3500, 0x54);
@@ -75,8 +82,9 @@ public class CpuIndirectModeTest extends TestCase {
        assertEquals(0x20, cpu.getProcessorStatus());
    }

+    @Test
    public void test_JMP_withOutIndirectBug() throws MemoryAccessException {
-        cpu.setBehavior(Cpu.CpuBehavior.NMOS_WITHOUT_INDIRECT_JMP_BUG);
+        cpu.setBehavior(Cpu.CpuBehavior.CMOS_6502);
        bus.write(0x3400, 0x22);
        bus.write(0x34ff, 0x00);
        bus.write(0x3500, 0x54);
@@ -87,8 +95,9 @@ public class CpuIndirectModeTest extends TestCase {
        assertEquals(0x20, cpu.getProcessorStatus());
    }

+    @Test
    public void test_JMP_cmos() throws MemoryAccessException {
-        cpu.setBehavior(Cpu.CpuBehavior.CMOS);
+        cpu.setBehavior(Cpu.CpuBehavior.CMOS_6502);
        bus.write(0x3400, 0x22);
        bus.write(0x34ff, 0x00);
        bus.write(0x3500, 0x54);
@@ -3,14 +3,21 @@ package com.loomcom.symon;
 import com.loomcom.symon.devices.Memory;
 import com.loomcom.symon.exceptions.MemoryAccessException;
 import junit.framework.TestCase;
+import org.junit.Before;
+import org.junit.Test;

-public class CpuIndirectXModeTest extends TestCase {
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class CpuIndirectXModeTest {

    protected Cpu    cpu;
    protected Bus    bus;
    protected Memory mem;

-    protected void setUp() throws Exception {
+    @Before
+    public void setUp() throws Exception {
        this.cpu = new Cpu();
        this.bus = new Bus(0x0000, 0xffff);
        this.mem = new Memory(0x0000, 0xffff);
@@ -47,7 +54,7 @@ public class CpuIndirectXModeTest extends TestCase {
    */

    /* ORA - Logical Inclusive OR - $1d */
-
+    @Test
    public void test_ORA() throws MemoryAccessException {
        // Set some initial values in memory
        bus.write(0x2c30, 0x00);
@@ -93,7 +100,7 @@ public class CpuIndirectXModeTest extends TestCase {
    }

    /* AND - Logical AND - $3d */
-
+    @Test
    public void test_AND() throws MemoryAccessException {
        bus.write(0x1a30, 0x00);
        bus.write(0x1a31, 0x11);
@@ -153,7 +160,7 @@ public class CpuIndirectXModeTest extends TestCase {
    }

    /* EOR - Exclusive OR - $5d */
-
+    @Test
    public void test_EOR() throws MemoryAccessException {
        bus.write(0xab40, 0x00);
        bus.write(0xab41, 0xff);
@@ -162,7 +169,7 @@ public class CpuIndirectXModeTest extends TestCase {

        cpu.setXRegister(0x30);

-        bus.loadProgram(0xa9, 0x88,         // LDA #$88
+        bus.loadProgram(0xa9, 0x88,        // LDA #$88
                        0x5d, 0x10, 0xab,  // EOR $ab10,X
                        0x5d, 0x11, 0xab,  // EOR $ab11,X
                        0x5d, 0x12, 0xab,  // EOR $ab12,X
@@ -189,7 +196,7 @@ public class CpuIndirectXModeTest extends TestCase {
    }

    /* ADC - Add with Carry - $7d */
-
+    @Test
    public void test_ADC() throws MemoryAccessException {
        bus.write(0xab40, 0x01);
        bus.write(0xab41, 0xff);
@@ -290,6 +297,7 @@ public class CpuIndirectXModeTest extends TestCase {
        assertTrue(cpu.getCarryFlag());
    }

+    @Test
    public void test_ADC_IncludesCarry() throws MemoryAccessException {
        bus.write(0xab40, 0x01);

@@ -307,6 +315,7 @@ public class CpuIndirectXModeTest extends TestCase {
        assertFalse(cpu.getCarryFlag());
    }

+    @Test
    public void test_ADC_DecimalMode() throws MemoryAccessException {
        bus.write(0xab40, 0x01);
        bus.write(0xab41, 0x99);
@@ -404,7 +413,7 @@ public class CpuIndirectXModeTest extends TestCase {
    }

    /* STA - Store Accumulator - $9d */
-
+    @Test
    public void test_STA() throws MemoryAccessException {
        cpu.setXRegister(0x30);

@@ -438,7 +447,7 @@ public class CpuIndirectXModeTest extends TestCase {
    }

    /* LDA - Load Accumulator - $bd */
-
+    @Test
    public void test_LDA() throws MemoryAccessException {
        bus.write(0xab42, 0x00);
        bus.write(0xab43, 0x0f);
@@ -467,7 +476,7 @@ public class CpuIndirectXModeTest extends TestCase {
    }

    /* CMP - Compare Accumulator - $dd */
-
+    @Test
    public void test_CMP() throws MemoryAccessException {
        bus.write(0xab40, 0x00);
        bus.write(0xab41, 0x80);
@@ -498,7 +507,7 @@ public class CpuIndirectXModeTest extends TestCase {
    }

    /* SBC - Subtract with Carry - $fd */
-
+    @Test
    public void test_SBC() throws MemoryAccessException {
        bus.write(0xab40, 0x01);

@@ -557,6 +566,7 @@ public class CpuIndirectXModeTest extends TestCase {
        assertTrue(cpu.getCarryFlag());
    }

+    @Test
    public void test_SBC_IncludesNotOfCarry() throws MemoryAccessException {
        bus.write(0xab40, 0x01);

@@ -602,6 +612,7 @@ public class CpuIndirectXModeTest extends TestCase {

    }

+    @Test
    public void test_SBC_DecimalMode() throws MemoryAccessException {
        bus.write(0xab40, 0x01);
        bus.write(0xab50, 0x11);
@@ -241,6 +241,7 @@ public class CpuTest extends TestCase {

    public void testSetProcessorStatus() {
        // Default
+
        assertFalse(cpu.getZeroFlag());
        assertFalse(cpu.getZeroFlag());
        assertFalse(cpu.getIrqDisableFlag());
@@ -384,6 +385,41 @@ public class CpuTest extends TestCase {
        assertFalse(cpu.getCpuState().irqAsserted);
    }

+    public void testIrqDoesNotSetBRK() throws Exception {
+        // Ensure the IRQ disable flag is cleared
+        cpu.clearIrqDisableFlag();
+
+        // Set the IRQ vector
+        bus.write(0xffff, 0x12);
+        bus.write(0xfffe, 0x34);
+
+        // Create an IRQ handler at 0x1234
+        cpu.setProgramCounter(0x1234);
+        bus.loadProgram(0xa9, 0x33,  // LDA #$33
+                        0x69, 0x01); // ADC #$01
+
+        cpu.setProgramCounter(0x0200);
+        // Create a little program at 0x0200
+        bus.loadProgram(0x18,        // CLC
+                        0xa9, 0x01,  // LDA #$00
+                        0x69, 0x01); // ADC #$01
+
+        cpu.step();
+        assertEquals(0x0201, cpu.getProgramCounter()); // First instruction executed.
+        assertEquals(0x00, cpu.getAccumulator());
+
+        cpu.step();
+        assertEquals(0x0203, cpu.getProgramCounter());
+        assertEquals(0x01, cpu.getAccumulator());
+
+        cpu.assertIrq();
+
+        cpu.step();
+        assertTrue(cpu.getIrqDisableFlag()); // Should have been set by the IRQ
+        assertFalse(cpu.getBreakFlag());
+
+    }
+
    public void testIrqHonorsIrqDisabledFlag() throws Exception {
        // Ensure the IRQ disable flag is set
        cpu.setIrqDisableFlag();
@@ -498,6 +534,37 @@ public class CpuTest extends TestCase {
        assertFalse(cpu.getCpuState().nmiAsserted);
    }

+    public void testNmiDoesNotSetBRK() throws Exception {
+        // Set the NMI vector to 0x1000
+        bus.write(0xfffb, 0x10);
+        bus.write(0xfffa, 0x00);
+
+        // Create an NMI handler at 0x1000
+        cpu.setProgramCounter(0x1000);
+        bus.loadProgram(0xa9, 0x33,  // LDA #$33
+                        0x69, 0x01); // ADC #$01
+
+        // Create a little program at 0x0200
+        cpu.setProgramCounter(0x0200);
+        bus.loadProgram(0x18,        // CLC
+                        0xa9, 0x01,  // LDA #$00
+                        0x69, 0x01); // ADC #$01
+
+        cpu.step();
+        assertEquals(0x0201, cpu.getProgramCounter()); // First instruction executed.
+        assertEquals(0x00, cpu.getAccumulator());
+
+        cpu.step();
+        assertEquals(0x0203, cpu.getProgramCounter());
+        assertEquals(0x01, cpu.getAccumulator());
+
+        cpu.assertNmi();
+
+        cpu.step();
+        assertFalse(cpu.getBreakFlag());
+
+}
+
    public void testNmiIgnoresIrqDisableFlag() throws Exception {
        // Set the IRQ disable flag, which should be ignored by the NMI
        cpu.setIrqDisableFlag();
@@ -0,0 +1,329 @@
+package com.loomcom.symon;
+
+import com.loomcom.symon.devices.Memory;
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertFalse;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Test for Zero Page Indirect addressing mode, found on some instructions
+ * in the 65C02 and 65816
+ */
+public class CpuZeroPageIndirectTest {
+    protected Cpu    cpu;
+    protected Bus    bus;
+    protected Memory mem;
+
+    private void makeCmosCpu() throws Exception {
+        makeCpu(InstructionTable.CpuBehavior.CMOS_6502);
+    }
+
+    private void makeNmosCpu() throws Exception {
+        makeCpu(InstructionTable.CpuBehavior.NMOS_6502);
+    }
+
+    private void makeCpu(InstructionTable.CpuBehavior behavior) throws Exception {
+        this.cpu = new Cpu(behavior);
+        this.bus = new Bus(0x0000, 0xffff);
+        this.mem = new Memory(0x0000, 0xffff);
+        bus.addCpu(cpu);
+        bus.addDevice(mem);
+
+        // Load the reset vector.
+        bus.write(0xfffc, Bus.DEFAULT_LOAD_ADDRESS & 0x00ff);
+        bus.write(0xfffd, (Bus.DEFAULT_LOAD_ADDRESS & 0xff00) >>> 8);
+
+        cpu.reset();
+    }
+
+    @Test
+    public void test_ora() throws Exception {
+        makeCmosCpu();
+
+        // Set some initial values in zero page.
+        bus.write(0x30, 0x00);
+        bus.write(0x31, 0x10);
+
+        bus.write(0x40, 0x01);
+        bus.write(0x41, 0x10);
+
+        bus.write(0x50, 0x02);
+        bus.write(0x51, 0x10);
+
+        bus.write(0x60, 0x03);
+        bus.write(0x61, 0x10);
+
+        bus.write(0x1000, 0x11);
+        bus.write(0x1001, 0x22);
+        bus.write(0x1002, 0x44);
+        bus.write(0x1003, 0x88);
+
+        bus.loadProgram(0x12, 0x30,  // ORA ($30)
+                        0x12, 0x40,  // ORA ($40)
+                        0x12, 0x50,  // ORA ($50)
+                        0x12, 0x60); // ORA ($60)
+
+
+        assertEquals(0x00, cpu.getAccumulator());
+
+        // 0x00 | 0x11 = 0x11
+        cpu.step();
+        assertEquals(0x11, cpu.getAccumulator());
+        assertFalse(cpu.getZeroFlag());
+        assertFalse(cpu.getNegativeFlag());
+
+        // 0x11 | 0x22 = 0x33
+        cpu.step();
+        assertEquals(0x33, cpu.getAccumulator());
+        assertFalse(cpu.getZeroFlag());
+        assertFalse(cpu.getNegativeFlag());
+
+        // 0x33 | 0x44 = 0x77
+        cpu.step();
+        assertEquals(0x77, cpu.getAccumulator());
+        assertFalse(cpu.getZeroFlag());
+        assertFalse(cpu.getNegativeFlag());
+
+        // 0x77 | 0x88 = 0xff
+        cpu.step();
+        assertEquals(0xff, cpu.getAccumulator());
+        assertFalse(cpu.getZeroFlag());
+        assertTrue(cpu.getNegativeFlag());
+    }
+
+    @Test
+    public void test_ora_requiresCmosCpu() throws Exception {
+        makeNmosCpu();
+
+        // Set some initial values in zero page.
+        bus.write(0x30, 0x00);
+        bus.write(0x31, 0x10);
+
+        bus.write(0x40, 0x01);
+        bus.write(0x41, 0x10);
+
+        bus.write(0x50, 0x02);
+        bus.write(0x51, 0x10);
+
+        bus.write(0x60, 0x03);
+        bus.write(0x61, 0x10);
+
+        bus.write(0x1000, 0x11);
+        bus.write(0x1001, 0x22);
+        bus.write(0x1002, 0x44);
+        bus.write(0x1003, 0x88);
+
+        bus.loadProgram(0x12, 0x30,  // ORA ($30)
+                        0x12, 0x40,  // ORA ($40)
+                        0x12, 0x50,  // ORA ($50)
+                        0x12, 0x60); // ORA ($60)
+
+
+        assertEquals(0x00, cpu.getAccumulator());
+
+        boolean zState = cpu.getZeroFlag();
+        boolean nState = cpu.getNegativeFlag();
+
+        // 0x00 | 0x11 = 0x11, but not implemented in NMOS cpu
+        cpu.step();
+        assertEquals(0x00, cpu.getAccumulator());
+        assertEquals(zState, cpu.getZeroFlag());         // unchanged
+        assertEquals(nState, cpu.getNegativeFlag());     // unchanged
+
+        // 0x11 | 0x22 = 0x33, but not implemented in NMOS cpu
+        cpu.step();
+        assertEquals(0x00, cpu.getAccumulator());
+        assertEquals(zState, cpu.getZeroFlag());         // unchanged
+        assertEquals(nState, cpu.getNegativeFlag());     // unchanged
+
+        // 0x33 | 0x44 = 0x77, but not implemented in NMOS cpu
+        cpu.step();
+        assertEquals(0x00, cpu.getAccumulator());
+        assertEquals(zState, cpu.getZeroFlag());         // unchanged
+        assertEquals(nState, cpu.getNegativeFlag());     // unchanged
+
+        // 0x77 | 0x88 = 0xff, but not implemented in NMOS cpu
+        cpu.step();
+        assertEquals(0x00, cpu.getAccumulator());
+        assertEquals(zState, cpu.getZeroFlag());         // unchanged
+        assertEquals(nState, cpu.getNegativeFlag());     // unchanged
+    }
+
+    @Test
+    public void test_and() throws Exception {
+        makeCmosCpu();
+
+        // Set some initial values in zero page.
+        bus.write(0x30, 0x00);
+        bus.write(0x31, 0x10);
+
+        bus.write(0x40, 0x01);
+        bus.write(0x41, 0x10);
+
+        bus.write(0x50, 0x02);
+        bus.write(0x51, 0x10);
+
+        bus.write(0x1000, 0x33);
+        bus.write(0x1001, 0x11);
+        bus.write(0x1002, 0x88);
+
+        bus.loadProgram(0x32, 0x30,  // AND ($30)
+                        0x32, 0x40,  // AND ($40)
+                        0x32, 0x50); // AND ($50)
+
+        cpu.setAccumulator(0xff);
+
+        // 0xFF & 0x33 == 0x33
+        cpu.step();
+        assertEquals(0x33, cpu.getAccumulator());
+        assertFalse(cpu.getZeroFlag());
+        assertFalse(cpu.getNegativeFlag());
+
+        // 0x33 & 0x11 == 0x11
+        cpu.step();
+        assertEquals(0x11, cpu.getAccumulator());
+        assertFalse(cpu.getZeroFlag());
+        assertFalse(cpu.getNegativeFlag());
+
+        // 0x11 & 0x80 == 0
+        cpu.step();
+        assertEquals(0, cpu.getAccumulator());
+        assertTrue(cpu.getZeroFlag());
+        assertFalse(cpu.getNegativeFlag());
+    }
+
+    @Test
+    public void test_and_requiresCmosCpu() throws Exception {
+        makeNmosCpu();
+
+        // Set some initial values in zero page.
+        bus.write(0x30, 0x00);
+        bus.write(0x31, 0x10);
+
+        bus.write(0x40, 0x01);
+        bus.write(0x41, 0x10);
+
+        bus.write(0x50, 0x02);
+        bus.write(0x51, 0x10);
+
+        bus.write(0x1000, 0x33);
+        bus.write(0x1001, 0x11);
+        bus.write(0x1002, 0x88);
+
+        bus.loadProgram(0x32, 0x30,  // AND ($30)
+                        0x32, 0x40,  // AND ($40)
+                        0x32, 0x50); // AND ($50)
+
+
+        cpu.setAccumulator(0xff);
+
+        boolean zState = cpu.getZeroFlag();
+        boolean nState = cpu.getNegativeFlag();
+
+        // 0xFF & 0x33 == 0x33, but not implemented in NMOS cpu
+        cpu.step();
+        assertEquals(0xff, cpu.getAccumulator());
+        assertEquals(zState, cpu.getZeroFlag());
+        assertEquals(nState, cpu.getNegativeFlag());
+
+        // 0x33 & 0x11 == 0x11, but not implemented in NMOS cpu
+        cpu.step();
+        assertEquals(0xff, cpu.getAccumulator());
+        assertEquals(zState, cpu.getZeroFlag());
+        assertEquals(nState, cpu.getNegativeFlag());
+
+        // 0x11 & 0x80 == 0, but not implemented in NMOS cpu
+        cpu.step();
+        assertEquals(0xff, cpu.getAccumulator());
+        assertEquals(zState, cpu.getZeroFlag());
+        assertEquals(nState, cpu.getNegativeFlag());
+    }
+
+    @Test
+    public void test_eor() throws Exception {
+        makeCmosCpu();
+
+        // Set some initial values in zero page.
+        bus.write(0x30, 0x00);
+        bus.write(0x31, 0x10);
+
+        bus.write(0x40, 0x01);
+        bus.write(0x41, 0x10);
+
+        bus.write(0x50, 0x02);
+        bus.write(0x51, 0x10);
+
+        bus.write(0x60, 0x03);
+        bus.write(0x61, 0x10);
+
+        bus.write(0x1000, 0x00);
+        bus.write(0x1001, 0xff);
+        bus.write(0x1002, 0x33);
+        bus.write(0x1003, 0x44);
+
+        bus.loadProgram(0x52, 0x30,  // AND ($30)
+                        0x52, 0x40,  // AND ($40)
+                        0x52, 0x50,  // EOR ($50)
+                        0x52, 0x60); // AND ($60)
+
+
+        cpu.setAccumulator(0x88);
+
+        cpu.step();
+        assertEquals(0x88, cpu.getAccumulator());
+
+        cpu.step();
+        assertEquals(0x77, cpu.getAccumulator());
+
+        cpu.step();
+        assertEquals(0x44, cpu.getAccumulator());
+
+        cpu.step();
+        assertEquals(0x00, cpu.getAccumulator());
+    }
+
+    @Test
+    public void test_eor_requiresCmosCpu() throws Exception {
+        makeNmosCpu();
+
+        // Set some initial values in zero page.
+        bus.write(0x30, 0x00);
+        bus.write(0x31, 0x10);
+
+        bus.write(0x40, 0x01);
+        bus.write(0x41, 0x10);
+
+        bus.write(0x50, 0x02);
+        bus.write(0x51, 0x10);
+
+        bus.write(0x60, 0x03);
+        bus.write(0x61, 0x10);
+
+        bus.write(0x1000, 0x00);
+        bus.write(0x1001, 0xff);
+        bus.write(0x1002, 0x33);
+        bus.write(0x1003, 0x44);
+
+        bus.loadProgram(0x52, 0x30,  // AND ($30)
+                        0x52, 0x40,  // AND ($40)
+                        0x52, 0x50,  // EOR ($50)
+                        0x52, 0x60); // AND ($60)
+
+
+        cpu.setAccumulator(0x88);
+
+        cpu.step();
+        assertEquals(0x88, cpu.getAccumulator());
+
+        cpu.step();
+        assertEquals(0x88, cpu.getAccumulator());
+
+        cpu.step();
+        assertEquals(0x88, cpu.getAccumulator());
+
+        cpu.step();
+        assertEquals(0x88, cpu.getAccumulator());
+    }
+}
Author	SHA1	Message	Date
Seth Morabito	4cca0b4663	Initial 65C02 Support First pass at adding CMOS 65C02 support for the following instructions and addressing modes: * ORA (ZP Indirect) * AND (ZP Indirect) * EOR (ZP Indirect) * ADC (ZP Indirect) * STA (ZP Indirect) * LDA (ZP Indirect) * CMP (ZP Indirect) * SBC (ZP Indirect)	2016-06-12 18:55:09 -07:00
Seth Morabito	5a2e057e69	Minor whitespace cleanup	2016-06-11 11:46:31 -07:00
Seth Morabito	da88aadda2	Merge pull request #15 from LIV2/master Correct BRK/IRQ behavior	2016-03-20 11:43:42 -07:00
Matt Harlum	657b69da6c	Cleanup my comments	2016-03-20 17:05:48 +11:00
Chris Cureau	f251e54174	Merge pull request #13 from sethm/cc65_update_patches update Makefiles and configuration for latest cc65	2016-03-14 20:01:12 -05:00
Chris Cureau	fcc57d9be4	update Makefiles and configuration for latest cc65	2016-01-12 08:14:38 -06:00
Seth Morabito	88eba2cdcb	Merge branch '1.2.branch'	2016-01-08 20:53:54 -08:00
Seth Morabito	b59fa63b63	Merge branch '1.2.branch'	2016-01-08 20:41:25 -08:00
Seth Morabito	c599df1cfb	Set version to 1.3.0-SNAPSHOT	2016-01-08 19:14:00 -08:00
Matt Harlum	8335cf5421	Correct BRK behaviour IRQ/NMI clear the BRK flag BRK is Non-Maskable	2015-06-01 08:58:17 +10:00