Version 1.0.10 - changes by Nick

- fixed disk stepping bug for Mabel's Mansion using my code from AppleWin
- patch loaded ROM's empty slots with faux-floating bus data so Mabel's Mansion works
- revert CPU status bug introduced in 1.0.9 - V and R used the same bit
- fixed BRK bug by adding extra PC increment

README.md

@@ -1,6 +1,10 @@
 # AppleIIGo
 Apple //e emulator Java applet
 
-Original version: Copyright 2006 Marc S. Ressl
+Original version: Copyright 2006 Marc S. Ressl, with parts adapted from code by
+- Steven E. Hugg
+- Doug Kwan
+- Randy Frank
+- Ben Koning
 
 Subsequent versions: Copyright 2008-2015 Nick Westgate

Source/AppleDisplay.java

@@ -2,7 +2,7 @@
 /**
  * AppleIIGo
  * Display processing
- * (C) 2006 by Marc S. Ressl (ressl@lonetree.com)
+ * Copyright 2006 by Marc S. Ressl (mressl@gmail.com)
  * Released under the GPL
  */
 
@@ -224,6 +224,18 @@ public class AppleDisplay implements Runnable {
 		return displayScale;
     }
 	
+	public int getSizeX()
+	{
+		precalcDisplay();
+		return displayScaledSizeX;
+	}
+	
+	public int getSizeY()
+	{
+		precalcDisplay();
+		return displayScaledSizeY;
+	}
+	
 	/**
 	 * Set refresh rate
 	 *

Source/AppleIIGo.java

@@ -2,13 +2,30 @@
 /**
  * AppleIIGo
  * The Java Apple II Emulator 
- * Copyright 2009 by Nick Westgate (Nick.Westgate@gmail.com)
+ * Copyright 2015 by Nick Westgate (Nick.Westgate@gmail.com)
- * Copyright 2006 by Marc S. Ressl (ressl@lonetree.com)
+ * Copyright 2006 by Marc S. Ressl (mressl@gmail.com)
  * Released under the GNU General Public License version 2 
  * See http://www.gnu.org/licenses/
  * 
  * Change list:
  * 
+ * Version 1.0.10 - changes by Nick:
+ * - fixed disk stepping bug for Mabel's Mansion using my code from AppleWin
+ * - patch loaded ROM's empty slots with faux-floating bus data so Mabel's Mansion works
+ * - revert CPU status bug introduced in 1.0.9 - V and R used the same bit
+ * - fixed BRK bug by adding extra PC increment
+ * - NOTE: decimal mode arithmetic fails some tests and should be fixed someday
+ * 
+ * Version 1.0.9 - changes by Nick:
+ * - fixed disk speed-up bug (Sherwood Forest reads with the drive motor off)
+ * - added check for 2IMG header ID
+ * - fixed processor status bugs in BRK, PLP, RTI, NMI, IRQ 
+ * 
+ * Version 1.0.8 - changes by Nick:
+ * - implemented disk writing (only in memory, not persisted)
+ * - added support for .2MG (2IMG) disk images, including lock flag and volume number
+ * - support meta tag for write protect in disk filename eg: NotWritable_Meta_DW0.dsk
+ * 
  * Version 1.0.7 - changes by Nick:
  * - fixed disk emulation bug (sense write protect entered write mode)
  * - now honour diskWritable parameter (but writing is not implemented)
@@ -75,7 +92,7 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 
 	private static final long serialVersionUID = -3302282815441501352L;
 	
-	final String version = "1.0.7";
+	final String version = "1.0.10";
 	final String versionString = "AppleIIGo Version " + version;
 	final String metaStart = "_meta_";
 
@@ -200,8 +217,6 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 		unmountDisk(0);
 		unmountDisk(1);
 	}
-	
-
 
 	// Public Java interface
 
@@ -247,7 +262,6 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 		debug("reset()");
 		apple.reset();
 	}
-	
 
 	public void setSpeed(int value) {
 		debug("setSpeed(" + value + ")");
@@ -292,7 +306,8 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 		}
 
 		try {
-			URL url = new URL(getCodeBase(), resource);
+			URL codeBase = getCodeBase();
+			URL url = new URL(codeBase, resource);
 			debug("resource: " + url.toString());
 
 			is = url.openStream();
@@ -378,6 +393,7 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 			DataInputStream is = openInputStream(resource, diskname);
 			
 			int diskVolumeNumber = DiskII.DEFAULT_VOLUME;
+			boolean diskWritableOverride = diskWritable;
 
 			// handle disk meta tag for disk volume (etc?)
 			// could break this out into a method, but then multiple tags ...?
@@ -427,6 +443,10 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 							case ('d' << 16) + 'v':
 								diskVolumeNumber = operand;
 								break;
+
+							case ('d' << 16) + 'w':
+								diskWritableOverride = (operand != 0);
+								break;
 						}
 						command = 0;
 						operand = 0;
@@ -434,7 +454,7 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 				}
 			}
 			
-			success = disk.readDisk(drive, is, diskname.toString(), !diskWritable, diskVolumeNumber);
+			success = disk.readDisk(drive, is, diskname.toString(), !diskWritableOverride, diskVolumeNumber);
 			is.close();
 			showStatus("Drive " + (drive + 1) + ": " + resource);
 		} catch (Exception e) {
@@ -455,12 +475,13 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 		if (!diskWritable)
 			return;
 			
-		try {
+		// TODO: only for local disk cache when it's working
-			OutputStream os = openOutputStream(diskDriveResource[drive]);
+		//try {
-			disk.writeDisk(drive, os);
+			//OutputStream os = openOutputStream(diskDriveResource[drive]);
-			os.close();
+			//disk.writeDisk(drive, os);
-		} catch (Exception e) {
+			//os.close();
-		}
+		//} catch (Exception e) {
+		//}
 	}
 
 	/**
@@ -501,6 +522,16 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 		return (!isCpuPaused && disk.isMotorOn());
 	}
 
+	public int getSizeX()
+	{
+		return display.getSizeX();
+	}
+
+	public int getSizeY()
+	{
+		return display.getSizeY();
+	}
+
 	/**
  	 * KeyListener event handling
 	 */	
@@ -626,7 +657,7 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 				apple.stepInstructions(128);
 			}
 			break;
-		case KeyEvent.VK_CANCEL: // Ctrl-Pause/Break sends this (N/A on Mac)
+		case KeyEvent.VK_CANCEL: // Pause/Break sends this (as Mac OS swallows Ctrl-F12)
 		case KeyEvent.VK_F12:
 			if (e.isControlDown())
 				reset();
@@ -846,5 +877,5 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
 	 */
 	public void update(Graphics g) {
 		display.paint(g);
-	}	
+	}
 }

Source/AppleSpeaker.java

@@ -2,7 +2,7 @@
 /**
  * AppleIIGo
  * Speaker processing
- * (C) 2006 by Marc S. Ressl(ressl@lonetree.com)
+ * Copyright 2006 by Marc S. Ressl(mressl@gmail.com)
  * Released under the GPL
  */
 

Source/DiskII.java

@@ -2,8 +2,8 @@
 /**
  * AppleIIGo
  * Disk II Emulator
- * (C) 2006 by Marc S. Ressl(ressl@lonetree.com)
+ * Copyright 2015 by Nick Westgate (Nick.Westgate@gmail.com)
- * (C) 2009 by Nick Westgate (Nick.Westgate@gmail.com)
+ * Copyright 2006 by Marc S. Ressl(mressl@gmail.com)
  * Released under the GPL
  * Based on work by Doug Kwan
  */
@@ -32,15 +32,20 @@ public class DiskII extends Peripheral {
 	};	
 
 	// Constants
+	public static final int DEFAULT_VOLUME = 254;
 	private static final int NUM_DRIVES = 2;
 	private static final int DOS_NUM_SECTORS = 16;
 	private static final int DOS_NUM_TRACKS = 35;
+	private static final int MAX_PHYS_TRACK = (2 * DOS_NUM_TRACKS) - 1;
 	private static final int DOS_TRACK_BYTES = 256 * DOS_NUM_SECTORS;
 	private static final int RAW_TRACK_BYTES = 0x1A00; // 0x1A00 (6656) for .NIB (was 6250)
-	public static final int DEFAULT_VOLUME = 254;
+	private static final int STANDARD_2IMG_HEADER_ID = 0x32494D47;
+	private static final int STANDARD_2IMG_HEADER_SIZE = 64;
+	private static final int STANDARD_PRODOS_BLOCKS = 280;
 	
 	// Disk II direct access variables
 	private int drive = 0;
+	private int phases = 0;
 	private boolean isMotorOn = false;
 
 	private byte[][][] diskData = new byte[NUM_DRIVES][DOS_NUM_TRACKS][];
@@ -66,9 +71,10 @@ public class DiskII extends Peripheral {
 	 */
 
 	// Internal registers
-	private int latchAddress;
 	private int latchData;
 	private boolean writeMode;
+	private boolean loadMode;
+	private int driveSpin;
 	
 	// GCR encoding and decoding tables
 	private static final int[] gcrEncodingTable = {
@@ -119,104 +125,54 @@ public class DiskII extends Peripheral {
 	 * @param	address	Address
 	 */
 	public int ioRead(int address) {
-		int phase;
-		
 		switch (address & 0xf) {
 			case 0x0:
-			case 0x2:			
-			case 0x4:
-			case 0x6:
-				// Q0, Q1, Q2, Q3 off
-				break;
 			case 0x1:
-				// Q0 on
+			case 0x2:			
-				phase = currPhysTrack & 3;
-				if (phase == 1) {
-					if (currPhysTrack > 0)
-						currPhysTrack--;
-				} else if (phase == 3) {
-					if (currPhysTrack < ((2 * DOS_NUM_TRACKS) - 1))
-						currPhysTrack++;
-				}
-				//System.out.println("half track=" + currPhysTrack);
-				realTrack = diskData[drive][currPhysTrack >> 1];
-				break;
 			case 0x3:
-				// Q1 on
+			case 0x4:
-				phase = currPhysTrack & 3;
-				if (phase == 2) {
-					if (currPhysTrack > 0)
-						currPhysTrack--;
-				} else if (phase == 0) {
-					if (currPhysTrack < ((2 * DOS_NUM_TRACKS) - 1))
-						currPhysTrack++;
-				}
-				//System.out.println("half track=" + currPhysTrack);
-				realTrack = diskData[drive][currPhysTrack >> 1];
-				break;
 			case 0x5:
-				// Q2 on
+			case 0x6:
-				phase = currPhysTrack & 3;
-				if (phase == 3) {
-					if (currPhysTrack > 0)
-						currPhysTrack--;
-				} else if (phase == 1) {
-					if (currPhysTrack < ((2 * DOS_NUM_TRACKS) - 1))
-						currPhysTrack++;
-				}
-				//System.out.println("half track=" + currPhysTrack);
-				realTrack = diskData[drive][currPhysTrack >> 1];
-				break;
 			case 0x7:
-				// Q3 on
+				setPhase(address);
-				phase = currPhysTrack & 3;
-				if (phase == 0) {
-					if (currPhysTrack > 0)
-						currPhysTrack--;
-				} else if (phase == 2) {
-					if (currPhysTrack < ((2 * DOS_NUM_TRACKS) - 1))
-						currPhysTrack++;
-				}
-				//System.out.println("half track=" + currPhysTrack);
-				realTrack = diskData[drive][currPhysTrack >> 1];
 				break;
 			case 0x8:
-				// Motor off
 				isMotorOn = false;
 				break;
 			case 0x9:
-				// Motor on
 				isMotorOn = true;
 				break;
 			case 0xa:
-				// Drive 1
+				setDrive(0);
-				driveCurrPhysTrack[drive] = currPhysTrack;
-				drive = 0;
-				currPhysTrack = driveCurrPhysTrack[drive];
-
-				realTrack = diskData[drive][currPhysTrack >> 1];
 				break;
 			case 0xb:
-				// Drive 2
+				setDrive(1);
-				driveCurrPhysTrack[drive] = currPhysTrack;
-				drive = 1;
-				currPhysTrack = driveCurrPhysTrack[drive];
-
-				realTrack = diskData[drive][currPhysTrack >> 1];
 				break;
 			case 0xc:
-				return ioLatchC();
+				ioLatchC();
+				break;
 			case 0xd:
-				ioLatchD(0xff);
+				loadMode = true;
+				if (isMotorOn && !writeMode)
+				{
+					latchData &= 0x7F;
+					// TODO: check phase - write protect is forced if phase 1 is on [F9.7]
+					if (isWriteProtected[drive])
+					{
+						latchData |= 0x80;
+					}
+				}
 				break;
 			case 0xe:
-				return ioLatchE();
+				writeMode = false;
+				break;
 			case 0xf:
-				ioLatchF(0xff);
+				writeMode = true;
 				break;
 		}
 		
-		return rand.nextInt(256);
+		// only even addresses return the latch
+		return ((address & 1) == 0) ? latchData : rand.nextInt(256); // TODO: floating bus
     }
 	
 	/**
@@ -234,25 +190,39 @@ public class DiskII extends Peripheral {
 			case 0x5:
 			case 0x6:
 			case 0x7:
+				setPhase(address);
+				break;
 			case 0x8:
+				isMotorOn = false;
+				break;
 			case 0x9:
+				isMotorOn = true;
+				break;
 			case 0xa:
+				setDrive(0);
+				break;
 			case 0xb:
-				ioRead(address);
+				setDrive(1);
 				break;
 			case 0xc:
 				ioLatchC();
 				break;
 			case 0xd:
-				ioLatchD(value);
+				loadMode = true;
 				break;
 			case 0xe:
-				ioLatchE();
+				writeMode = false;
 				break;
 			case 0xf:
-				ioLatchF(value);
+				writeMode = true;
 				break;
 		}
+		
+		if (isMotorOn && writeMode && loadMode)
+		{
+			// any address writes latch for sequencer LD; OE1/2 irrelevant ['323 datasheet]
+			latchData = value;
+		}
     }
 	
 	/**
@@ -268,23 +238,71 @@ public class DiskII extends Peripheral {
 	 * Reset peripheral
 	 */
 	public void reset() {
-		ioRead(0x8);
+		drive = 0;
+		isMotorOn = false;
+		loadMode = false;
+		writeMode = false;
 	}
 
 	/**
  	 * Loads a disk
-	 *
-	 * @param	is			InputStream
-	 * @param	drive		Disk II drive
 	 */
 	public boolean readDisk(int drive, DataInputStream is, String name, boolean isWriteProtected, int volumeNumber) {
-		byte[] track = new byte[DOS_TRACK_BYTES];
-
-		String lowerName = name.toLowerCase();
-		boolean proDos = lowerName.indexOf(".po") != -1;
-		boolean nib = lowerName.indexOf(".nib") != -1;
-		
 		try {
+			byte[] track = new byte[DOS_TRACK_BYTES];
+			boolean proDos = false;
+			boolean nib = false;
+		
+			String lowerName = name.toLowerCase();
+			if (lowerName.indexOf(".2mg") != -1 || lowerName.indexOf(".2img") != -1)
+			{
+				// 2IMG, so check if we can handle it
+				byte[] header = new byte[STANDARD_2IMG_HEADER_SIZE];
+				is.readFully(header, 0, STANDARD_2IMG_HEADER_SIZE);
+
+				int id = (header[0x00] << 24) | (header[0x01] << 16) | (header[0x02] << 8) | (header[0x03]);
+				if (id != STANDARD_2IMG_HEADER_ID)
+					return false;
+
+				int headerSize = (header[0x09] << 8) | (header[0x08]);
+				if (headerSize != STANDARD_2IMG_HEADER_SIZE)
+					return false;
+				
+				int format = (header[0x0F] << 24) | (header[0x0E] << 16) | (header[0x0D] << 8) | (header[0x0C]);
+				if (format == 1)
+				{
+					proDos = true;
+					int blocks = (header[0x17] << 24) | (header[0x16] << 16) | (header[0x15] << 8) | (header[0x14]);
+					if (blocks != STANDARD_PRODOS_BLOCKS)
+						return false; // only handle standard 5.25 inch images
+				}
+				else if (format == 2)
+				{
+					nib = true;
+				}
+				else if (format != 0)
+				{
+					return false; // if not ProDOS, NIB or DSK
+				}
+				
+				// use write protected and volume number if present
+				int flags = (header[0x13] << 24) | (header[0x12] << 16) | (header[0x11] << 8) | (header[0x10]);
+				if ((flags & (1 << 31)) != 0)
+				{
+					isWriteProtected = true; // only override if set 
+				}
+				if ((flags & (1 << 8)) != 0)
+				{
+					volumeNumber = (flags & 0xFF);
+				}
+			}
+			else
+			{
+				// check for PO and NIB in the name
+				proDos = lowerName.indexOf(".po") != -1;
+				nib = lowerName.indexOf(".nib") != -1;
+			}
+
 			for (int trackNum = 0; trackNum < DOS_NUM_TRACKS; trackNum++) {
 				diskData[drive][trackNum] = new byte[RAW_TRACK_BYTES];
 
@@ -328,32 +346,33 @@ public class DiskII extends Peripheral {
 		return isMotorOn;
 	}
 
-
+	private void ioLatchC() {
-
+		loadMode = false;
-	/**
+		if (!writeMode)
-	 * I/O read Latch C
-	 *
-	 * @param	address	Address
-	 */
-	private int ioLatchC() {
-		latchAddress = 0xc;
-		if (writeMode)
-		{
-			// Write data: C0xD, C0xC
-			realTrack[currNibble] = (byte) latchData;
-		}
-		else
 		{
+			if (!isMotorOn)
+			{
+				// simple hack to fool RWTS SAMESLOT drive spin check (usually at $BD34)
+				driveSpin = (driveSpin + 1) & 0xF;
+				if (driveSpin == 0)
+				{
+					latchData = 0x7F;
+					return;
+				}
+			}
+
 			// Read data: C0xE, C0xC
 			latchData = (realTrack[currNibble] & 0xff);
 
-			// simple hack to help DOS find address prologues ($B94F)
+			// is RWTS looking for an address prologue? (RDADR)
-			if (/* fastDisk && */ latchData != 0xD5 && // TODO: fastDisk property to enable/disable 
+			if (/* fastDisk && */ // TODO: fastDisk property to enable/disable 
 				apple.memoryRead(apple.PC + 3) == 0xD5 && // #$D5
-				apple.memoryRead(apple.PC + 2) == 0xC9 && // CMP
+				apple.memoryRead(apple.PC + 2) == 0xC9 && // CMP (usually at $B94F)
 				apple.memoryRead(apple.PC + 1) == 0xFB && // PC - 3
-				apple.memoryRead(apple.PC + 0) == 0x10)   // BPL
+				apple.memoryRead(apple.PC + 0) == 0x10 &&  // BPL
+				latchData != 0xD5) 
 			{
+				// Y: find the next address prologues
 				int count = RAW_TRACK_BYTES / 16;
 				do
 				{
@@ -364,14 +383,7 @@ public class DiskII extends Peripheral {
 				}
 				while (latchData != 0xD5 && --count > 0);
 			}
-			// simple hack to fool DOS 3.3 RWTS drive spin detect routine ($BD34)
+			// N: skip invalid nibbles we padded the track buffer with 
-			else if (apple.memoryRead(apple.PC - 3) == 0xDD && // CMP $C08C,X
-				apple.memoryRead(apple.PC + 1) == 0x03 &&      // PC + 3 
-				apple.memoryRead(apple.PC + 0) == 0xD0)        // BNE
-			{
-				return 0x7F; 
-			}
-			// skip invalid nibbles we padded the track buffer with 
 			else if (latchData == 0x7F)
 			{
 				int count = RAW_TRACK_BYTES / 16;
@@ -385,51 +397,61 @@ public class DiskII extends Peripheral {
 				while (latchData == 0x7F && --count > 0);
 			}
 		}
+		else
+		{
+			// Write data: C0xD, C0xC
+			realTrack[currNibble] = (byte) latchData;
+		}
 
 		currNibble++;
 		if (currNibble >= RAW_TRACK_BYTES)
 			currNibble = 0;
+	}
 
-		return latchData;
+	private void setPhase(int address) {
-	}
+		int phase = (address >> 1) & 3;
-	
+		int phase_bit = (1 << phase);
-	/**
+
-	 * I/O write Latch D
+		// update the magnet states
-	 *
+		if ((address & 1) != 0)
-	 * @param	address	Address
+		{
-	 */
+			// phase on
-	private void ioLatchD(int value) {
+			phases |= phase_bit;
-		// Prepare for write protect sense
+		}
-		latchAddress = 0xd;
+		else
-	}
+		{
-	
+			// phase off
-	/**
+			phases &= ~phase_bit;
-	 * I/O read Latch E
-	 *
-	 * @param	address	Address
-	 */
-	private int ioLatchE() {
-		// Read write-protect: C0xD, C0xE
-		if (latchAddress == 0xd) {
-			latchAddress = 0xe;
-			return isWriteProtected[drive] ? 0x80 : 0x00;
 		}
 
-		writeMode = false;
+		// check for any stepping effect from a magnet
-		latchAddress = 0xe;
+		// - move only when the magnet opposite the cog is off
-		return 0x3c;
+		// - move in the direction of an adjacent magnet if one is on
+		// - do not move if both adjacent magnets are on
+		// momentum and timing are not accounted for ... maybe one day!
+		int direction = 0;
+		if ((phases & (1 << ((currPhysTrack + 1) & 3))) != 0)
+			direction += 1;
+		if ((phases & (1 << ((currPhysTrack + 3) & 3))) != 0)
+			direction -= 1;
+
+		// apply magnet step, if any
+		if (direction != 0)
+		{
+			currPhysTrack += direction;
+			if (currPhysTrack < 0)
+				currPhysTrack = 0;
+			else if (currPhysTrack > MAX_PHYS_TRACK)
+				currPhysTrack = MAX_PHYS_TRACK;
+		}
+		realTrack = diskData[drive][currPhysTrack >> 1];
 	}
 
-	/**
+	private void setDrive(int newDrive) {
-	 * I/O write Latch F
+		driveCurrPhysTrack[drive] = currPhysTrack;
-	 *
+		drive = newDrive;
-	 * @param	address	Address
+		currPhysTrack = driveCurrPhysTrack[drive];
-	 */
+		realTrack = diskData[drive][currPhysTrack >> 1];
-	private void ioLatchF(int value) {
-		// Prepare write
-		writeMode = true;
-		latchData = value;
-		latchAddress = 0xf;
 	}
 
 	/**

Source/Em6502.java

@@ -1,12 +1,14 @@
+import java.io.PrintWriter;
+
 
 /**
  * AppleIIGo
  * Apple II Emulator for J2SE
- * (C) 2006 by Marc S. Ressl(ressl@lonetree.com)
+ * Copyright 2006 by Marc S. Ressl(mressl@gmail.com)
  * Released under the GPL
  * Adapted from code by Doug Kwan
  * Adapted from code by Randy Frank randy@tessa.iaf.uiowa.edu
- * Adapted from code (C) 1989 Ben Koning [556498717 408/738-1763 ben@apple.com]
+ * Adapted from code Copyright 1989 Ben Koning [556498717 408/738-1763 ben@apple.com]
  */
 
 public class Em6502 {
@@ -78,6 +80,7 @@ public class Em6502 {
 	public static final int FLAG_I = (1 << 2);
 	public static final int FLAG_D = (1 << 3);
 	public static final int FLAG_B = (1 << 4);
+	public static final int FLAG_R = (1 << 5);
 	public static final int FLAG_V = (1 << 6);
 	public static final int FLAG_N = (1 << 7);
 	/*
@@ -120,6 +123,8 @@ public class Em6502 {
 	 * Constructor
 	 */
 	public Em6502() {
+//		createRunFile(); // TODO: for debugging - disable
+		
 		// Init BCD tables
 		BCDTableAdd = new int[512];
 		BCDTableSub = new int[512];
@@ -133,6 +138,10 @@ public class Em6502 {
 			BCDTableSub[i] = ((i & 0x0f) <= 0x09) ? i : (i - 0x06);
 			BCDTableSub[i] -= ((BCDTableSub[i] & 0xf0) <= 0x90) ? 0 : 0x60;
 		}
+
+		// Init CPU
+        S = 0xFF;
+		P = FLAG_B | FLAG_R;
 	}
 	
 	/*
@@ -154,7 +163,7 @@ public class Em6502 {
 	 */
 	private final void setN(boolean b) {if (b) P |= FLAG_N; else P &= ~FLAG_N;}
 	private final void setV(boolean b) {if (b) P |= FLAG_V; else P &= ~FLAG_V;}
-	private final void setB(boolean b) {if (b) P |= FLAG_B; else P &= ~FLAG_B;}
+//	private final void setB(boolean b) {if (b) P |= FLAG_B; else P &= ~FLAG_B;}
 	private final void setD(boolean b) {if (b) P |= FLAG_D; else P &= ~FLAG_D;}
 	private final void setI(boolean b) {if (b) P |= FLAG_I; else P &= ~FLAG_I;}
 	private final void setZ(boolean b) {if (b) P |= FLAG_Z; else P &= ~FLAG_Z;}
@@ -294,9 +303,48 @@ public class Em6502 {
 		clock++;
 	}
 
+//	private PrintWriter runFile;
+//	private boolean runFlag = false;
+//
+//	private void createRunFile()
+//	{
+//		try
+//		{
+//			//runFile = new PrintWriter("C:\\Dev\\Emulators\\AppleIIGo\\AppleIIGoRun.txt");
+//		}
+//		catch (Exception ex)
+//		{
+//			// swallow
+//		}
+//	}
+//
+//	private final void writeRunFile(int opcode)
+//	{
+//		if (PC == 0x2000)
+//			runFlag = true;
+//		if (
+//				runFlag &&
+//				(PC > 0x1000)
+//				&&
+//				(PC < 0xC000)
+//			)
+//		{
+//			if (runFile != null)
+//			{
+//				setN(getFN());
+//				setZ(getFZ());
+//				setC(getFC());
+//
+//				runFile.printf("%04X-%02X P=%02X A=%02X\r\n", PC, opcode, P, A);
+//				runFile.flush();
+//			}
+//		}
+//	}
+	
 	/** This executes a single instruction. */
 	private final void executeInstruction() {
 		opcode = memoryRead(PC);
+//		writeRunFile(opcode); // TODO: for debugging = disable
 		PC++;
 		
 		switch(opcode) {
@@ -530,13 +578,13 @@ public class Em6502 {
 			break;
 			
 		case 0x00:	// BRK
+			PC++;
 			push(PC >> 8);	// save PCH, PCL & P
 			push(PC);
 			setN(getFN());
 			setZ(getFZ());
 			setC(getFC());
-			setB(true);
+			push(P); // B and R always set
-			push(P);
 			setI(true);
 			PC = memoryRead(0xfffe);
 			PC |= memoryRead(0xffff) << 8;
@@ -1043,7 +1091,7 @@ public class Em6502 {
 			break;
 			
 		case 0x28:	// PLP
-			P = pop() | 0x20; // fix bug in bit5 of P
+			P = pop() | FLAG_B | FLAG_R; // B and R always set
 			setFC(getC());
 			setFNZ(getN(), getZ());
 			clock += 4;
@@ -1144,7 +1192,7 @@ public class Em6502 {
 			break;
 			
 		case 0x40:	// RTI
-			P = pop() | 0x20; // bit 5 bug of 6502
+			P = pop() | FLAG_B | FLAG_R; // B and R always set
 			setFC(getC());
 			setFNZ(getN(), getZ());
 			PC = pop();	// splitting is necessary
@@ -1570,13 +1618,13 @@ public class Em6502 {
 		if ((exceptionRegister & SIG_6502_RESET) != 0) {
 			onReset();
 			
-			PC = memoryRead(0xfffc);
-			PC |= (memoryRead(0xfffd) << 8);
-			S = (S - 3) & 0xff;
-			setI(true);
 			setD(false); // not on NMOS 6502
 			setFC(getC());
 			setFNZ(getN(), getZ());
+			S = (S - 3) & 0xff;
+			setI(true);
+			PC = memoryRead(0xfffc);
+			PC |= (memoryRead(0xfffd) << 8);
 			clock += 7;
 			exceptionRegister &= ~SIG_6502_RESET;
 		}
@@ -1590,7 +1638,8 @@ public class Em6502 {
 			setN(getFN());
 			setZ(getFZ());
 			setC(getFC());
-			push(P);
+			push(P & ~FLAG_B);
+			setI(true);
 			PC = memoryRead(0xfffa);
 			PC |= memoryRead(0xfffb) << 8;
 			clock += 7;
@@ -1608,8 +1657,7 @@ public class Em6502 {
 				setN(getFN());
 				setZ(getFZ());
 				setC(getFC());
-				setB(false);
+				push(P & ~FLAG_B);
-				push(P);
 				setI(true);
 				PC = memoryRead(0xfffe);
 				PC |= memoryRead(0xffff) << 8;

Source/EmAppleII.java

@@ -2,7 +2,7 @@
 /**
  * AppleIIGo
  * Apple II Emulator for J2ME
- * (C) 2006 by Marc S. Ressl(ressl@lonetree.com)
+ * Copyright 2006 by Marc S. Ressl(mressl@gmail.com)
  * Released under the GPL
  */
 
@@ -264,6 +264,17 @@ public class EmAppleII extends Em6502 implements Runnable {
 		System.arraycopy(rom, offset + 0x3000, mem, MEM_ROM_INTERNAL + 0x00000, 0x01000);
 		System.arraycopy(rom, offset + 0x3800, mem, MEM_ROM_EXTERNAL + 0x00800, 0x00800);
 
+		for (int slot = 0x100; slot <= 0x700; slot += 0x100)
+		{
+			if (mem[MEM_ROM_EXTERNAL + slot] == 0)
+			{
+				// 0 data is a bad default for empty external slots (e.g. Mabel's Mansion reboots)
+				// so ideally we would emulate the floating bus, but for now we just hardcode 0xA0
+				for (int i = 0; i <= 0xFF; i++)
+					mem[MEM_ROM_EXTERNAL + slot + i] = (byte)0xA0;
+			}
+		}
+
 		return true;
 	}
 

Source/Paddle.java

@@ -2,7 +2,7 @@
 /**
 * AppleIIGo
  * Apple II Emulator for J2ME
- * (C) 2006 by Marc S. Ressl(ressl@lonetree.com)
+ * Copyright 2006 by Marc S. Ressl(mressl@gmail.com)
  * Released under the GPL
  */
 

Source/Peripheral.java

@@ -2,7 +2,7 @@
 /**
  * AppleIIGo
  * Slot interface
- * (C) 2006 by Marc S. Ressl(ressl@lonetree.com)
+ * Copyright 2006 by Marc S. Ressl(mressl@gmail.com)
  * Released under the GPL
  * Based on work by Steven E. Hugg
  */