# Game Boy BIOS & Game Boy Color BIOS Dumping Tool



## G4S0 (Aug 1, 2018)

What tool should I use to dump the Game Boy BIOS and the Game Boy Color BIOS?

The latest version is included.


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## Thunder Hawk (Aug 1, 2018)

G4S0 said:


> What tool should I use to dump the Game Boy BIOS and the Game Boy Color BIOS?


It would probably require a lot of soldering and hardware to dump it off the chips.



G4S0 said:


> The latest version is included.


What do you mean?


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## G4S0 (Aug 1, 2018)

Thunder Hawk said:


> It would probably require a lot of soldering and hardware to dump it off the chips.


Well, I would guess that nobody made an easy-to-use tool to dump the BIOS.


Thunder Hawk said:


> What do you mean?


Something like version 1.0 of the tool.


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## MichiS97 (Aug 1, 2018)

G4S0 said:


> Well, I would guess that nobody made an easy-to-use tool to dump the BIOS.
> 
> Something like version 1.0 of the tool.


It's basically impossible to write a tool for that. I doubt you could pull that off on an Everdrive with a homebrew tool.


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## G4S0 (Aug 1, 2018)

MichiS97 said:


> It's basically impossible to write a tool for that. I doubt you could pull that off on an Everdrive with a homebrew tool.


There could be a homebrew tool like a Game Boy (Color) BIOS dumper that can dump a BIOS on an Everdrive flash card.


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## MichiS97 (Aug 1, 2018)

G4S0 said:


> There could be a homebrew tool like a Game Boy (Color) BIOS dumper that can dump a BIOS on an Everdrive flash card.


I don't think that's technically possible


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## tech3475 (Aug 1, 2018)

Apparently the BIOS's are protected when they're done.

The GBC was dumped after glitching (?) while the GBA can be dumped into SRAM of a flash cart.

GBC:
https://kemenaran.winosx.com/posts/gameboy-color-boot-rom-dumped/
http://www.fpgb.org/?page_id=17

GBA:
https://mgba.io/2017/06/30/cracking-gba-bios/
https://github.com/mgba-emu/bios-dump

Note: These are just what I found after a quick search and I haven't tested anything.


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## MichiS97 (Aug 1, 2018)

Judging from the Gameboy pandocs, the BIOS is stored on a ROM built into the gameboy itself which becomes inaccessible after any cartridge is launched. Therefore, it isn't possible to write a homebrew dumper. You'd have to work with soldering and probably glitching the microcontrollers to dump anything


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## Ryccardo (Aug 1, 2018)

MichiS97 said:


> Judging from the Gameboy pandocs, the BIOS is stored on a ROM built into the gameboy itself which becomes inaccessible after any cartridge is launched. Therefore, it isn't possible to write a homebrew dumper. You'd have to work with soldering and probably glitching the microcontrollers to dump anything


It's not externally accessible either, the only option is clock skipping/power glitching/rgh/whatever you want to call it to skip the instruction that disables the bootrom, THEN it can be dumped by homebrew (that sends it over the serial port, maybe it copies it to SRAM, etc)


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## MichiS97 (Aug 1, 2018)

Ryccardo said:


> It's not externally accessible either, the only option is clock skipping/power glitching/rgh/whatever you want to call it to skip the instruction that disables the bootrom, THEN it can be dumped by homebrew (that sends it over the serial port, maybe it copies it to SRAM, etc)


Yeah I just read how it was actually accomplished. Impressive stuff tbh


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## G4S0 (Aug 1, 2018)

MichiS97 said:


> Yeah I just read how it was actually accomplished. Impressive stuff tbh


So to dump a Game Boy BIOS or a Game Boy Color BIOS, all I have to do is to insert a flash card like EverDrive, boot up a BIOS ROM, and maybe swap cartridges to get a BIOS dump?


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## MichiS97 (Aug 1, 2018)

G4S0 said:


> So to dump a Game Boy BIOS or a Game Boy Color BIOS, all I have to do is to insert a flash card like EverDrive, boot up a BIOS ROM, and maybe swap cartridges to get a BIOS dump?


Wh... What? How did any of my or somebody else's posts lead you to that conclusion?


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## Ryccardo (Aug 1, 2018)

G4S0 said:


> So to dump a Game Boy BIOS or a Game Boy Color BIOS, all I have to do is to insert a flash card like EverDrive, boot up a BIOS ROM, and maybe swap cartridges to get a BIOS dump?


No, you have to get a flashcard (or bootleg, etc) with a dumper software, then do nasty hardware tricks at the right time (which can be figured out by... looking at an already dumped/disassembled bootrom to figure out instruction timings; the first time it was done by chance) to skip the instruction that disables the bootrom, then using said dumper software (which may or may not publicly exist) as needed


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## G4S0 (Aug 1, 2018)

I kept searching for a Game Boy (Color) BIOS dumper software, which it took so much of my time.

https://image.ibb.co/iqmu3z/G01036814_03_mainboard_front.jpg
https://image.ibb.co/mpTwGK/2014_01_31_T19_04_06_562_Z_gbamp2s_installed.jpg


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## Normmatt (Aug 2, 2018)

This talk is very interesting and this is the most relevant part of the talk.


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## G4S0 (Aug 3, 2018)

Now, I have a whole new reason to dump the GB (+GBC) BIOS.

The first method is to probe (or solder).
The second method is to use a CPU on a test board.
The third method is to de-cap the CPU.

I might be sure about using a flash cartridge and a ROM that dumps the boot ROM.

The key that I figured out is to stop the un-mapping, in order to dump the boot ROM.


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## G4S0 (Aug 3, 2018)

Sorry for the double post, but I know that there are some GBA BIOS-dumping tools that can dump the GBA BIOS simply. What if there are the GB-and-GBC BIOS-dumping tools that can dump their BIOS just like the GBA BIOS-dumping tools?


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