Be warned that the gameboy color bios we currently have is not the 'real' one: it was ?accidentally? left in the rom of pokemon stadium for n64, possibly a leftover from an older version of that hardware which actually had a varant of the cgb cpu in it; the bios is 'incomplete': it doesn't do the near-constant cart logo or header checks which the real cgb bios does, and it doesn't have the table of various different color palettes predone for games which are selected based on a ?hash? of the header title of each game. It also does NOT result in the correct register states when the cart code is started which may cause all sorts of weird errors.
In fact, I don't even know if the 'pokemon stadium cgb bios' even checks the header flags to set up the 'undocumented' registers to switch the windowing and sprite priority registers to the proper modes for cgb vs dmg games. it probably doesn't.

Based on preliminary decapsulation work on the cgb cpu, the bios is 3 roms:
a 256 byte one (probably from 0x0000-0x00FF) which is similar to the dmg one
a 512 byte one (probably from 0x0150-0x034F) which holds the logo and code to decompress it
and a 1792 byte one (address unknown so far) which holds the big lookup table of games and what colors they should have.
None of these roms have actually been read out yet due to difficulty staining the die, but we know how large they are.


Last edited by Lord Nightmare; 09/11/09 10:53 PM.

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