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AppleIIGo
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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
This commit is contained in:
sicklittlemonkey 2015-08-10 00:11:49 +12:00
parent 68cfda45c1
commit fe27c7d1e8
4 changed files with 104 additions and 99 deletions
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11
Source/AppleIIGo.java
View File

@ -2,13 +2,20 @@
/**
* AppleIIGo
* The Java Apple II Emulator
* Copyright 2014 by Nick Westgate (Nick.Westgate@gmail.com)
* Copyright 2015 by Nick Westgate (Nick.Westgate@gmail.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
@ -85,7 +92,7 @@ public class AppleIIGo extends Applet implements KeyListener, ComponentListener,
private static final long serialVersionUID = -3302282815441501352L;
final String version = "1.0.9";
final String version = "1.0.10";
final String versionString = "AppleIIGo Version " + version;
final String metaStart = "_meta_";

131
Source/DiskII.java
View File

@ -2,7 +2,7 @@
/**
* AppleIIGo
* Disk II Emulator
* Copyright 2014 by Nick Westgate (Nick.Westgate@gmail.com)
* Copyright 2015 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
@ -36,6 +36,7 @@ public class DiskII extends Peripheral {
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)
private static final int STANDARD_2IMG_HEADER_ID = 0x32494D47;
@ -44,6 +45,7 @@ public class DiskII extends Peripheral {
// 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][];
@ -72,7 +74,7 @@ public class DiskII extends Peripheral {
private int latchData;
private boolean writeMode;
private boolean loadMode;
private boolean driveSpin;
private int driveSpin;
// GCR encoding and decoding tables
private static final int[] gcrEncodingTable = {
@ -348,28 +350,29 @@ public class DiskII extends Peripheral {
loadMode = false;
if (!writeMode)
{
if (!isMotorOn)
{
// simple hack to fool DOS SAMESLOT drive spin check (usually at $BD34)
driveSpin = !driveSpin;
if (driveSpin)
{
latchData = 0x7F;
return;
}
}
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 && */ // 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
latchData != 0xD5)
{
// Y: find the next address prologues
int count = RAW_TRACK_BYTES / 16;
do
{
@ -380,8 +383,8 @@ public class DiskII extends Peripheral {
}
while (latchData != 0xD5 && --count > 0);
}
// skip invalid nibbles we padded the track buffer with
else if (latchData == 0x7F) // TODO: maybe the above covers this?
// N: skip invalid nibbles we padded the track buffer with
else if (latchData == 0x7F)
{
int count = RAW_TRACK_BYTES / 16;
do
@ -406,68 +409,42 @@ public class DiskII extends Peripheral {
}
private void setPhase(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
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
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
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
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;
int phase = (address >> 1) & 3;
int phase_bit = (1 << phase);
// update the magnet states
if ((address & 1) != 0)
{
// phase on
phases |= phase_bit;
}
else
{
// phase off
phases &= ~phase_bit;
}
// check for any stepping effect from a magnet
// - move only when the magnet opposite the cog is off
// - 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) {

50
Source/Em6502.java
View File

@ -80,7 +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 << 6);
public static final int FLAG_R = (1 << 5);
public static final int FLAG_V = (1 << 6);
public static final int FLAG_N = (1 << 7);
/*
@ -123,7 +123,7 @@ public class Em6502 {
* Constructor
*/
public Em6502() {
// createRunFile();
// createRunFile(); // TODO: for debugging - disable
// Init BCD tables
BCDTableAdd = new int[512];
@ -163,7 +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;}
@ -304,38 +304,47 @@ public class Em6502 {
}
// private PrintWriter runFile;
// private boolean runFlag = false;
//
// private void createRunFile()
// {
// try
// {
// runFile = new PrintWriter("C:\\Users\\Public\\AppleIIGoRun.txt");
// //runFile = new PrintWriter("C:\\Dev\\Emulators\\AppleIIGo\\AppleIIGoRun.txt");
// }
// catch (Exception ex)
// {
// // swallow
// }
// }
//
// private final void writeRunFile(int opcode)
// {
// if (
// (PC > 0x0500)
// &&
// (PC < 0x0600)
// )
// {
// setN(getFN());
// setZ(getFZ());
// setC(getFC());
// 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();
// }
// 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);
// writeRunFile(opcode); // TODO: for debugging = disable
PC++;
switch(opcode) {
@ -569,12 +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());
push(P); // break flag is always set
push(P); // B and R always set
setI(true);
PC = memoryRead(0xfffe);
PC |= memoryRead(0xffff) << 8;
@ -1081,7 +1091,7 @@ public class Em6502 {
break;
case 0x28: // PLP
P = pop() | FLAG_B | FLAG_R; // fix bug in bit5 of P
P = pop() | FLAG_B | FLAG_R; // B and R always set
setFC(getC());
setFNZ(getN(), getZ());
clock += 4;
@ -1182,7 +1192,7 @@ public class Em6502 {
break;
case 0x40: // RTI
P = pop() | FLAG_B | FLAG_R; // 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

11
Source/EmAppleII.java
View File

@ -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;
}