# GB to GBC Conversion



## Arecaidian Fox (Dec 27, 2016)

I need to know how to convert a GB ROM into a GBC ROM. I tried simply renaming the file extension, and while it did boot in VBA, it failed to convert with Ultimate GBC VC Injector. The reason it needs to be converted is so it will play as a GameBoy Color game, and not be forced into greyscale like the older GB VC emulator does.


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## FAST6191 (Dec 27, 2016)

It would probably be easier to hack a palette into the GB emulator (assuming you have not got a real emulator you can use instead).
GB games were built for greyscale, some of the later ones had palettes built in should they detect they are running on a GBC (or GBA) and a few would have actual colours from the SNES super game boy addon but that is a whole other kettle of fish. Any you might have seen on the GBC with the button combos on power up were not as much colours as just premade palettes that you could try instead.
I don't know what goes with the dual systems GB games and the GBC VC emulator as far as forcing one mode or another, I would hope if it is there though that it goes for the GBC option. If it is as poor an emulator as most other VC stuff (someone mentioned something about DS games on the 3ds the other day, if you can get one of the DS homebrew GBC emulators booting then that would be a better option) then you might get somewhere with http://problemkaputt.de/pandocs.htm#cgbregisters but it is not a cute change this byte in the header option if so. Mind you there is a header byte that might be worth looking at http://problemkaputt.de/pandocs.htm#thecartridgeheader


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## Arecaidian Fox (Dec 27, 2016)

I'll try tinkering with the header value for detecting which console the cart is meant for. Thanks for the info!


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## Arecaidian Fox (Dec 27, 2016)

Something interesting resulted from that. VBA loaded a white screen with the game audio when running the header-modified ROM, and Ultimate GBC VC Injector no longer threw an error when importing it. But upon installing the CIA file and booting it up on the 3DS, I actually got game visuals and audio both, but the game was still in greyscale.


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## Lumstar (Dec 27, 2016)

I don't know. 3DS may not support the preset lists of colors a GBC can apply to older games.

If you want to convert a whole game into a GBC game, that more resembles porting it to another platform.
You'd have to dive in and reprogram it to add color palettes, any needed tile mapping changes, or whatever.


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## Arecaidian Fox (Dec 27, 2016)

Lumstar said:


> I don't know. 3DS may not support the preset lists of colors a GBC can apply to older games.
> 
> If you want to convert a whole game into a GBC game, that more resembles porting it to another platform.
> You'd have to dive in and reprogram it to add color palettes, any needed tile mapping changes, or whatever.


The game in question has an IPS patch applied, adding color, alternate graphics and alternate music. It works fine on most other emulators, save for those where you can't override the mode (regular, Color, SGB, etc.).


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## Lumstar (Dec 27, 2016)

Arecaidian Fox said:


> The game in question has an IPS patch applied, adding color, alternate graphics and alternate music. It works fine on most other emulators, save for those where you can't override the mode (regular, Color, SGB, etc.).



That sounds like the patch itself was written incorrectly. Most GBC games, when played on a capable system, automatically and can only use GBC mode.
There's exceptions like R-Type DX having non-color versions of the games.


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## nl255 (Dec 27, 2016)

Lumstar said:


> That sounds like the patch itself was written incorrectly. Most GBC games, when played on a capable system, automatically and can only use GBC mode.
> There's exceptions like R-Type DX having non-color versions of the games.



Yeah, some GBC homebrew is like that as well such as Ultima 3 which while actually a GBC only game some emulators will try to run it in GB mode.


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## Drenn (Dec 27, 2016)

Arecaidian Fox said:


> The game in question has an IPS patch applied, adding color, alternate graphics and alternate music. It works fine on most other emulators, save for those where you can't override the mode (regular, Color, SGB, etc.).


It would help if you linked to the patch in question. As others have said, it sounds like something is wrong with it if emulators aren't automatically detecting it as a GBC rom.

It's possible that changing byte 0x143 in the rom header to 0xC0 or 0x80 will fix it, although you'd need to fix the header checksum as well (assuming VC checks for that).


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## Arecaidian Fox (Dec 28, 2016)

Drenn said:


> It would help if you linked to the patch in question. As others have said, it sounds like something is wrong with it if emulators aren't automatically detecting it as a GBC rom.
> 
> It's possible that changing byte 0x143 in the rom header to 0xC0 or 0x80 will fix it, although you'd need to fix the header checksum as well (assuming VC checks for that).


Yeah, I used info provided earlier to change that byte, but I didn't realize I'd need to change the checksum as well (never done this before). Anyway, this is the patch in question.


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## Drenn (Dec 28, 2016)

Arecaidian Fox said:


> Yeah, I used info provided earlier to change that byte, but I didn't realize I'd need to change the checksum as well (never done this before). Anyway, this is the patch in question.


Oh. That isn't a gameboy color hack. Just like the original pokemon red and blue, it supports colorization through the Super Gameboy, not the Gameboy Color. VC doesn't support the super gameboy. On the other hand, this should work on VC.


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## raulpica (Dec 28, 2016)

Drenn said:


> Just like the original pokemon red and blue, it supports colorization through the Super Gameboy, not the Gameboy Color.


As soon as I saw the thread title, I knew that was the issue  Too bad I didn't notice the thread earlier!

Took me a long time to find out that my fav GB games were being colorised thanks to the SGB mode, and not GBC, when I was a kid!


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## Lumstar (Dec 28, 2016)

Heh, yeah. Super Gameboy is totally different hardware from Gameboy Color.
Its colors are applied using the SNES palette, and the final image goes through the SNES video output. You might've wondered why SGB doesn't need a separate AV cable.


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## memelord21213 (Feb 9, 2021)

I'm having the same issue with sml2 dx (jp version)


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