Skip to content

Adds a VIC44K mode to JVIC #20

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
lanceewing merged 5 commits into from
Feb 11, 2026
Merged

Adds a VIC44K mode to JVIC #20

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
b7eb1c5
Started adding support for the VIC44K mode.
lanceewing Feb 7, 2026
089b6e8
Adding more of the VIC44K implementation. Very nearly working.
lanceewing Feb 8, 2026
41700dd
More updates for VIC44K mode. Mostly working now.
lanceewing Feb 10, 2026
fd30ddb
Updated VIC44K ROM.
lanceewing Feb 10, 2026
297d923
Fixed VIC44K ROM. Found another colour address reference that needed …
lanceewing Feb 10, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 9 additions & 0 deletions assets/data/programs.json
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -781,6 +781,15 @@
"machineType": "VIC44",
"ram": "RAM_UNEXPANDED"
},
{
"name": "VIC44K",
"displayName": "VIC 44K",
"filePath": "",
"fileType": "ROM",
"iconPath": "screenshots/V/VIC44/VIC44.png",
"machineType": "VIC44K",
"ram": "RAM_UNEXPANDED"
},
{
"name": "Whack-E",
"filePath": "https://archive.org/download/tosec-20161111-commodore-vic-20_20170305/TOSEC.2016.11.11.Commodore.VIC20.AlphaBot.zip/TOSEC.2016.11.11.Commodore.VIC20.AlphaBot%2FCommodore%20VIC20%20-%20Games%20-%20%5BPRG%5D%2FWhack-E%20%282009%29%28McCrea%2C%20Steve%29.zip",
Expand Down
Binary file added assets/roms/vic_44k_basic.rom
View file
Open in desktop
Binary file not shown.
Binary file added assets/roms/vic_44k_kernal.rom
View file
Open in desktop
Binary file not shown.
2 changes: 2 additions & 0 deletions core/src/main/java/emu/jvic/JVic.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -172,6 +172,8 @@ private void applyTvConfig(AppConfigItem appConfigItem, String tv) {
case "VIC44":
appConfigItem.setMachineType("VIC44");
break;
case "VIC44K":
appConfigItem.setMachineType("VIC44K");
default:
break;
}
Expand Down
42 changes: 42 additions & 0 deletions core/src/main/java/emu/jvic/JVicRunner.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -192,6 +192,48 @@ public MachineInputProcessor getMachineInputProcessor() {
return (machineScreen != null? machineScreen.getMachineInputProcessor() : null);
}

public byte[] loadKernalRom(MachineType machineType) {
byte[] kernalRom = null;

switch (machineType) {
case NTSC:
kernalRom = Gdx.files.internal("roms/kernal_ntsc.rom").readBytes();
break;
case PAL:
kernalRom = Gdx.files.internal("roms/kernal_pal.rom").readBytes();
break;
case VIC44:
kernalRom = Gdx.files.internal("roms/vic_44_kernal.rom").readBytes();
break;
case VIC44K:
kernalRom = Gdx.files.internal("roms/vic_44k_kernal.rom").readBytes();
break;
}

return kernalRom;
}

public byte[] loadBasicRom(MachineType machineType) {
byte[] basicRom = null;

switch (machineType) {
case NTSC:
basicRom = Gdx.files.internal("roms/basic.rom").readBytes();
break;
case PAL:
basicRom = Gdx.files.internal("roms/basic.rom").readBytes();
break;
case VIC44:
basicRom = Gdx.files.internal("roms/vic_44_basic.rom").readBytes();
break;
case VIC44K:
basicRom = Gdx.files.internal("roms/vic_44k_basic.rom").readBytes();
break;
}

return basicRom;
}

public abstract void start(AppConfigItem appConfigItem);

public abstract void reset();
Expand Down
3 changes: 3 additions & 0 deletions core/src/main/java/emu/jvic/Machine.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
import emu.jvic.sound.libgdx.GdxSoundGenerator;
import emu.jvic.video.Vic;
import emu.jvic.video.Vic44;
import emu.jvic.video.Vic44k;
import emu.jvic.video.Vic6560;
import emu.jvic.video.Vic6561;

Expand Down Expand Up @@ -138,6 +139,8 @@ public Callable<Queue<char[]>> init(
// Create the VIC chip and configure it as per the current TV type.
if (machineType.isVIC44()) {
vic = new Vic44(pixelData, machineType, snapshot);
} else if (machineType.isVIC44K()) {
vic = new Vic44k(pixelData, machineType, snapshot);
} else if (machineType.isNTSC()) {
vic = new Vic6560(pixelData, machineType, snapshot);
} else {
Expand Down
1 change: 1 addition & 0 deletions core/src/main/java/emu/jvic/MachineScreen.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,7 @@ public MachineScreen(JVic jvic, JVicRunner jvicRunner, DialogHandler dialogHandl
createScreenResourcesForMachineType(MachineType.PAL);
createScreenResourcesForMachineType(MachineType.NTSC);
createScreenResourcesForMachineType(MachineType.VIC44);
createScreenResourcesForMachineType(MachineType.VIC44K);

warpSpeedIcon = new Texture("png/warp_speed_icon.png");
cameraIcon = new Texture("png/camera_icon.png");
Expand Down
8 changes: 7 additions & 1 deletion core/src/main/java/emu/jvic/MachineType.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,9 @@ public enum MachineType {

NTSC(1022727, 260, 263, 199, 252, 49, 8, 60),

VIC44(1108405, 568, 312, 440, 272, 103, 31, 50);
VIC44(1108405, 568, 312, 440, 272, 103, 31, 50),

VIC44K(1108405, 568, 312, 440, 272, 103, 31, 50);

private int cyclesPerSecond;
private int totalScreenWidth;
Expand Down Expand Up @@ -147,4 +149,8 @@ public boolean isNTSC() {
public boolean isVIC44() {
return equals(VIC44);
}

public boolean isVIC44K() {
return equals(VIC44K);
}
}
253 changes: 153 additions & 100 deletions core/src/main/java/emu/jvic/memory/Vic20Memory.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -75,111 +75,164 @@ public Vic20Memory(Cpu6502 cpu, Vic vic, Via6522 via1, Via6522 via2, int ramExpa
*/
private void initVicMemory(Vic vic, Via6522 via1, Via6522 via2, byte[] basicRom, byte[] kernalRom, byte[] charRom) {

// This 1K of RAM is always present.
mapChipToMemory(new VicBusRamChip(), 0x0000, 0x03FF);

// The next 3K of memory may have RAM or may be unconnected.
mapChipToMemory((ramExpansion & RAM_1) != 0 ? new RamChip() : new UnconnectedMemory(), 0x0400, 0x07FF);
mapChipToMemory((ramExpansion & RAM_2) != 0 ? new RamChip() : new UnconnectedMemory(), 0x0800, 0x0BFF);
mapChipToMemory((ramExpansion & RAM_3) != 0 ? new RamChip() : new UnconnectedMemory(), 0x0C00, 0x0FFF);

// This 4K of RAM is always present.
mapChipToMemory(new VicBusRamChip(), 0x1000, 0x1FFF);

// The next three 8K blocks may have RAM or may be unconnected.
mapChipToMemory((ramExpansion & BLK_1) != 0 ? new RamChip() : new UnconnectedMemory(), 0x2000, 0x3FFF);
mapChipToMemory((ramExpansion & BLK_2) != 0 ? new RamChip() : new UnconnectedMemory(), 0x4000, 0x5FFF);
mapChipToMemory((ramExpansion & BLK_3) != 0 ? new RamChip() : new UnconnectedMemory(), 0x6000, 0x7FFF);

mapChipToMemory(new VicBusRomChip(), 0x8000, 0x8FFF, charRom);

if (machineType.isVIC44K()) {
initVic44KMemory(vic, via1, via2);

} else {
// This 1K of RAM is always present.
mapChipToMemory(new VicBusRamChip(), 0x0000, 0x03FF);

// The next 3K of memory may have RAM or may be unconnected.
mapChipToMemory((ramExpansion & RAM_1) != 0 ? new RamChip() : new UnconnectedMemory(), 0x0400, 0x07FF);
mapChipToMemory((ramExpansion & RAM_2) != 0 ? new RamChip() : new UnconnectedMemory(), 0x0800, 0x0BFF);
mapChipToMemory((ramExpansion & RAM_3) != 0 ? new RamChip() : new UnconnectedMemory(), 0x0C00, 0x0FFF);

// This 4K of RAM is always present.
mapChipToMemory(new VicBusRamChip(), 0x1000, 0x1FFF);

// The next three 8K blocks may have RAM or may be unconnected.
mapChipToMemory((ramExpansion & BLK_1) != 0 ? new RamChip() : new UnconnectedMemory(), 0x2000, 0x3FFF);
mapChipToMemory((ramExpansion & BLK_2) != 0 ? new RamChip() : new UnconnectedMemory(), 0x4000, 0x5FFF);
mapChipToMemory((ramExpansion & BLK_3) != 0 ? new RamChip() : new UnconnectedMemory(), 0x6000, 0x7FFF);

mapChipToMemory(new VicBusRomChip(), 0x8000, 0x8FFF, charRom);

// These are the standard locations for the VIC, VIA1 and VIA2 chips.
mapChipToMemory(vic, 0x9000, 0x900F);
mapChipToMemory(via1, 0x9110, 0x911F);
mapChipToMemory(via2, 0x9120, 0x912F);

// The rest of the $9XXX address space, other than colour RAM, is not fully
// decoded. Every address in that range is going to select at least one of
// the VIC, VIA1 or VIA2 chips though, but sometimes it will select 2 or 3
// of them at once!! So we emulate this behaviour below.
NotFullyDecodedMemory vicVia1 = new NotFullyDecodedMemory(new MemoryMappedChip[] { vic, via1 });
NotFullyDecodedMemory vicVia2 = new NotFullyDecodedMemory(new MemoryMappedChip[] { vic, via2 });
NotFullyDecodedMemory via1Via2 = new NotFullyDecodedMemory(new MemoryMappedChip[] { via1, via2 });
NotFullyDecodedMemory vicVia1Via2 = new NotFullyDecodedMemory(new MemoryMappedChip[] { vic, via1, via2 });

mapChipToMemory(vicVia1, 0x9010, 0x901F);
mapChipToMemory(vicVia2, 0x9020, 0x902F);
mapChipToMemory(vicVia1Via2, 0x9030, 0x903F);
mapChipToMemory(vic, 0x9040, 0x904F);
mapChipToMemory(vicVia1, 0x9050, 0x905F);
mapChipToMemory(vicVia2, 0x9060, 0x906F);
mapChipToMemory(vicVia1Via2, 0x9070, 0x907F);
mapChipToMemory(vic, 0x9080, 0x908F);
mapChipToMemory(vicVia1, 0x9090, 0x909F);
mapChipToMemory(vicVia2, 0x90A0, 0x90AF);
mapChipToMemory(vicVia1Via2, 0x90B0, 0x90BF);
mapChipToMemory(vic, 0x90C0, 0x90CF);
mapChipToMemory(vicVia1, 0x90D0, 0x90DF);
mapChipToMemory(vicVia2, 0x90E0, 0x90EF);
mapChipToMemory(vicVia1Via2, 0x90F0, 0x90FF);

mapChipToMemory(vic, 0x9100, 0x910F); // Unconnected VIC address bus space.
mapChipToMemory(via1Via2, 0x9130, 0x913F);
mapChipToMemory(vic, 0x9140, 0x914F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9150, 0x915F);
mapChipToMemory(via2, 0x9160, 0x916F);
mapChipToMemory(via1Via2, 0x9170, 0x917F);
mapChipToMemory(vic, 0x9180, 0x918F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9190, 0x919F);
mapChipToMemory(via2, 0x91A0, 0x91AF);
mapChipToMemory(via1Via2, 0x91B0, 0x91BF);
mapChipToMemory(vic, 0x91C0, 0x91CF); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x91D0, 0x91DF);
mapChipToMemory(via2, 0x91E0, 0x91EF);
mapChipToMemory(via1Via2, 0x91F0, 0x91FF);
mapChipToMemory(vic, 0x9200, 0x920F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9210, 0x921F);
mapChipToMemory(via2, 0x9220, 0x922F);
mapChipToMemory(via1Via2, 0x9230, 0x923F);
mapChipToMemory(vic, 0x9240, 0x924F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9250, 0x925F);
mapChipToMemory(via2, 0x9260, 0x926F);
mapChipToMemory(via1Via2, 0x9270, 0x927F);
mapChipToMemory(vic, 0x9280, 0x928F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9290, 0x929F);
mapChipToMemory(via2, 0x92A0, 0x92AF);
mapChipToMemory(via1Via2, 0x92B0, 0x92BF);
mapChipToMemory(vic, 0x92C0, 0x92CF); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x92D0, 0x92DF);
mapChipToMemory(via2, 0x92E0, 0x92EF);
mapChipToMemory(via1Via2, 0x92F0, 0x92FF);
mapChipToMemory(vic, 0x9300, 0x930F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9310, 0x931F);
mapChipToMemory(via2, 0x9320, 0x932F);
mapChipToMemory(via1Via2, 0x9330, 0x933F);
mapChipToMemory(vic, 0x9340, 0x934F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9350, 0x935F);
mapChipToMemory(via2, 0x9360, 0x936F);
mapChipToMemory(via1Via2, 0x9370, 0x937F);
mapChipToMemory(vic, 0x9380, 0x938F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9390, 0x939F);
mapChipToMemory(via2, 0x93A0, 0x93AF);
mapChipToMemory(via1Via2, 0x93B0, 0x93BF);
mapChipToMemory(vic, 0x93C0, 0x93CF); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x93D0, 0x93DF);
mapChipToMemory(via2, 0x93E0, 0x93EF);
mapChipToMemory(via1Via2, 0x93F0, 0x93FF);

// The colour RAM lives at this spot by default.
mapChipToMemory(new NibbleRamChip(), 0x9400, 0x97FF);

mapChipToMemory(vic, 0x9800, 0x9FFF); // Unconnected VIC address bus space.

// It is possible to connect RAM in this block, even though it would normally be
// a cartridge ROM.
mapChipToMemory((ramExpansion & BLK_5) != 0 ? new RamChip() : new UnconnectedMemory(), 0xA000, 0xBFFF);
}

mapChipToMemory(new RomChip(), 0xC000, 0xDFFF, basicRom);
mapChipToMemory(new RomChip(), 0xE000, 0xFFFF, kernalRom);

if (machineType.isVIC44() || machineType.isVIC44K()) {
vic.setCharRom(charRom);
}
}

/**
* Initialises the memory for the VIC44K machine.
*
* @param vic The VIC chip to map to memory.
* @param via1 The VIA #1 chip to map to memory.
* @param via2 The VIA #2 chip to map to memory.
*/
private void initVic44KMemory(Vic vic, Via6522 via1, Via6522 via2) {
// All Expansion RAM in the VIC44K (BLK5/BLK1/BLK2/BLK3)
mapChipToMemory(new RamChip(), 0x0000, 0x7FFF);

mapChipToMemory(new VicBusRamChip(), 0x8000, 0xB7FF);

mapChipToMemory(new NibbleRamChip(), 0xB800, 0xBBFF);

// These are the standard locations for the VIC, VIA1 and VIA2 chips.
mapChipToMemory(vic, 0x9000, 0x900F);
mapChipToMemory(via1, 0x9110, 0x911F);
mapChipToMemory(via2, 0x9120, 0x912F);

// The rest of the $9XXX address space, other than colour RAM, is not fully
// decoded. Every address in that range is going to select at least one of
// the VIC, VIA1 or VIA2 chips though, but sometimes it will select 2 or 3
// of them at once!! So we emulate this behaviour below.
mapChipToMemory(vic, 0xBC00, 0xBC0F);
mapChipToMemory(via1, 0xBD10, 0xBD1F);
mapChipToMemory(via2, 0xBD20, 0xBD2F);

NotFullyDecodedMemory vicVia1 = new NotFullyDecodedMemory(new MemoryMappedChip[] { vic, via1 });
NotFullyDecodedMemory vicVia2 = new NotFullyDecodedMemory(new MemoryMappedChip[] { vic, via2 });
NotFullyDecodedMemory via1Via2 = new NotFullyDecodedMemory(new MemoryMappedChip[] { via1, via2 });
NotFullyDecodedMemory vicVia1Via2 = new NotFullyDecodedMemory(new MemoryMappedChip[] { vic, via1, via2 });

mapChipToMemory(vicVia1, 0x9010, 0x901F);
mapChipToMemory(vicVia2, 0x9020, 0x902F);
mapChipToMemory(vicVia1Via2, 0x9030, 0x903F);
mapChipToMemory(vic, 0x9040, 0x904F);
mapChipToMemory(vicVia1, 0x9050, 0x905F);
mapChipToMemory(vicVia2, 0x9060, 0x906F);
mapChipToMemory(vicVia1Via2, 0x9070, 0x907F);
mapChipToMemory(vic, 0x9080, 0x908F);
mapChipToMemory(vicVia1, 0x9090, 0x909F);
mapChipToMemory(vicVia2, 0x90A0, 0x90AF);
mapChipToMemory(vicVia1Via2, 0x90B0, 0x90BF);
mapChipToMemory(vic, 0x90C0, 0x90CF);
mapChipToMemory(vicVia1, 0x90D0, 0x90DF);
mapChipToMemory(vicVia2, 0x90E0, 0x90EF);
mapChipToMemory(vicVia1Via2, 0x90F0, 0x90FF);
mapChipToMemory(vic, 0x9100, 0x910F); // Unconnected VIC address bus space.
mapChipToMemory(via1Via2, 0x9130, 0x913F);
mapChipToMemory(vic, 0x9140, 0x914F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9150, 0x915F);
mapChipToMemory(via2, 0x9160, 0x916F);
mapChipToMemory(via1Via2, 0x9170, 0x917F);
mapChipToMemory(vic, 0x9180, 0x918F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9190, 0x919F);
mapChipToMemory(via2, 0x91A0, 0x91AF);
mapChipToMemory(via1Via2, 0x91B0, 0x91BF);
mapChipToMemory(vic, 0x91C0, 0x91CF); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x91D0, 0x91DF);
mapChipToMemory(via2, 0x91E0, 0x91EF);
mapChipToMemory(via1Via2, 0x91F0, 0x91FF);
mapChipToMemory(vic, 0x9200, 0x920F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9210, 0x921F);
mapChipToMemory(via2, 0x9220, 0x922F);
mapChipToMemory(via1Via2, 0x9230, 0x923F);
mapChipToMemory(vic, 0x9240, 0x924F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9250, 0x925F);
mapChipToMemory(via2, 0x9260, 0x926F);
mapChipToMemory(via1Via2, 0x9270, 0x927F);
mapChipToMemory(vic, 0x9280, 0x928F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9290, 0x929F);
mapChipToMemory(via2, 0x92A0, 0x92AF);
mapChipToMemory(via1Via2, 0x92B0, 0x92BF);
mapChipToMemory(vic, 0x92C0, 0x92CF); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x92D0, 0x92DF);
mapChipToMemory(via2, 0x92E0, 0x92EF);
mapChipToMemory(via1Via2, 0x92F0, 0x92FF);
mapChipToMemory(vic, 0x9300, 0x930F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9310, 0x931F);
mapChipToMemory(via2, 0x9320, 0x932F);
mapChipToMemory(via1Via2, 0x9330, 0x933F);
mapChipToMemory(vic, 0x9340, 0x934F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9350, 0x935F);
mapChipToMemory(via2, 0x9360, 0x936F);
mapChipToMemory(via1Via2, 0x9370, 0x937F);
mapChipToMemory(vic, 0x9380, 0x938F); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x9390, 0x939F);
mapChipToMemory(via2, 0x93A0, 0x93AF);
mapChipToMemory(via1Via2, 0x93B0, 0x93BF);
mapChipToMemory(vic, 0x93C0, 0x93CF); // Unconnected VIC address bus space.
mapChipToMemory(via1, 0x93D0, 0x93DF);
mapChipToMemory(via2, 0x93E0, 0x93EF);
mapChipToMemory(via1Via2, 0x93F0, 0x93FF);

// The colour RAM lives at this spot by default.
mapChipToMemory(new NibbleRamChip(), 0x9400, 0x97FF);

mapChipToMemory(vic, 0x9800, 0x9FFF); // Unconnected VIC address bus space.

// It is possible to connect RAM in this block, even though it would normally be
// a cartridge ROM.
mapChipToMemory((ramExpansion & BLK_5) != 0 ? new RamChip() : new UnconnectedMemory(), 0xA000, 0xBFFF);

mapChipToMemory(new RomChip(), 0xC000, 0xDFFF, basicRom);
mapChipToMemory(new RomChip(), 0xE000, 0xFFFF, kernalRom);

for (int i=0xBC00; i<=0xBFFF; i++) {
boolean isVic = ((i & 0xFF00) == 0xBC00);
boolean isVia1 = ((i & 0x0030) == 0x0010);
boolean isVia2 = ((i & 0x0030) == 0x0020);

if (isVic && !isVia1 && !isVia2) mapChipToMemory(vic, i, i);
if (isVic && isVia1 && !isVia2) mapChipToMemory(vicVia1, i, i);
if (isVic && !isVia1 && isVia2) mapChipToMemory(vicVia2, i, i);
if (isVic && isVia1 && isVia2) mapChipToMemory(vicVia1Via2, i, i);
if (!isVic && isVia1 && !isVia2) mapChipToMemory(via1, i, i);
if (!isVic && !isVia1 && isVia2) mapChipToMemory(via2, i, i);
if (!isVic && isVia1 && isVia2) mapChipToMemory(via1Via2, i, i);

// TODO: Does this need vic bus version of unconnected memory?
if (!isVic && !isVia1 && !isVia2) mapChipToMemory(new UnconnectedMemory(), i, i);
}
}

/**
Expand Down
Loading
Loading