# GB/C mod for DS



## Deleted User (May 8, 2018)

Thinking of modding a DS to be able to boot the GB mode of it's GBA processor and also add a link cable port.
What considerations would be needed for this? Presumably it just needs a 5v switch to power a GB cart but I've seen no evidence of anyone pulling it off.

Also wondering if it would be possible to somehow attach GBA components to the DS components of a 3DS to boot via a ROM of the DS start up menu and make a fully backwards compatable handheld (in custom housing to hold all that of course)


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## cracker (May 8, 2018)

There is no GB/C hardware built into the DS. The GB/C uses essentially a Z80 (old 8bit CPU) and the DS uses only 32bit ARM. In order to have a GB/C that would run games and have a link port you would need to make a Frankenstein's monster of DS and GB/C hardware along with a way to interface with the LCD or do something like a Raspiboy. In short, it would require pretty nice skills in EE to pull off what you want.


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## Deleted User (May 8, 2018)

cracker said:


> There is no GB/C hardware built into the DS. The GB/C uses essentially a Z80 (old 8bit CPU) and the DS uses only 32bit ARM. In order to have a GB/C that would run games and have a link port you would need to make a Frankenstein's monster of DS and GB/C hardware along with a way to interface with the LCD or do something like a Raspiboy. In short, it would require pretty nice skills in EE to pull off what you want.


Ah, I thought it was like the Micro where the GBC mode was just in the Advance processor but inaccessible.

perhaps the mod could be done by using GB Micro parts


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## AdamFX990 (May 8, 2018)

cracker said:


> There is no GB/C hardware built into the DS. The GB/C uses essentially a Z80 (old 8bit CPU) and the DS uses only 32bit ARM. In order to have a GB/C that would run games and have a link port you would need to make a Frankenstein's monster of DS and GB/C hardware along with a way to interface with the LCD or do something like a Raspiboy. In short, it would require pretty nice skills in EE to pull off what you want.



But we all know ambition trumps logic. I reckon we'll see a working example by the end of the month. /s


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## Deleted User (May 8, 2018)

AdamFX990 said:


> But we all know ambition trumps logic. I reckon we'll see a working example by the end of the month. /s


I can't even find a helpful DS teardown so I won't bother to invest in this.

Apparently the DS uses a beefed up ARM7 in conjunction with an ARM 9 and the ARM 7 can be slowed down for GBA games.
But if I understand correctly, the DS's ARM7 chip lacks the Z80 die of the GBA's ARM7 processor that allowed GB mode.

So based on what I understand thusfar it seems like i would need some really complicated set up with a GB micro board that activates when the DS/3DS signals to enter GBA mode.
As much as I'd love to be able to play all my hand held cartridges on one custom system, I don't think I'm ambitious enough to try to be the first with this

Modding a GB Micro sounds simple but even with backwards compatibility I can't justify owning a Micro which is probably why noone else seems to have bothered.


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## Deleted User (May 9, 2018)

Y'know what, if I want to do some handheld hybriding, then why don't I put New 3DS and GBA motherboards into a custom shell and hook both up to share screens and buttons with some sort of switch between the 2. The end result might be a thick form factor, but honestly my hands have been getting OOS from portable devices since the DS Lite.
I could even add things like an HDMI out and a controller port

The only thing I see missing with this is it wont enable DS games to connect to GBA carts. Maybe I should just throw in a DS too, then it would have 2 slots for GBA and DS games.


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## Jayro (May 9, 2018)

Since when can the GBA micro play GBC games without using emulation?


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## Minox (May 9, 2018)

Jayro said:


> Since when can the GBA micro play GBC games without using emulation?


It doesn't. GB Micro was their first handheld where they stripped away GB/GBC functionality.


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## Jayro (May 9, 2018)

Minox said:


> It doesn't. GB Micro was their first handheld where they stripped away GB/GBC functionality.


That's what I thought... And the original DS carried that over, playing only GB Advance games. Glad we now have DSIhax, it's nice plying Drenn's GameYob right from the home menu.


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## Localhorst86 (May 9, 2018)

Jayro said:


> Since when can the GBA micro play GBC games without using emulation?


FYI, it's called "GameBoy Micro" not "Gameboy Advance Micro". And yes, the GB Micro was the first Gameboy Model to not be backwards compatible with its predecessors. There is, however, a way to boot into the GBC mode:

https://github.com/AntonioND/gba-switch-to-gbc

Not entirely sure what exactly this means or if there is any way to utilize this, though. Just something that's interesting, the Micro still contains the GBC BIOS...


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## migles (May 9, 2018)

@Snugglevixen as stated above, GBC mode is extremly likely a no no.

what about add back the link port to the DS ? is just a matter of finding the pinout in the pcb and modify the bios with the link support back?


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## cracker (May 9, 2018)

It could be done through emulation with a custom GB "cartridge" that routes a link port to the IO using bitbanging.


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