Prototype GBA BIOS

No clue where I picked this up, but it's definitely strange. In addition to the changed sound, using this BIOS causes minor graphics corruption in some game

Prototypes by system/Game Boy Advance - Hidden Palace

Prototype GBA BIOS

Prototype GBA BIOS

Proto:Game Boy Advance BIOS - The Cutting Room Floor

PLCC Replaces Game Boy Cartridge ROM

GBATEK - sabia

Altered GBA BIOS ? - The Independent Video Game

Marcus Taylor Resume buzz 12-2016

Ultra Rare Gameboy Advance Prototype Found! : r/retrogaming

Nintendo GameCube Prototype From Space World 2000 Expo is

After almost 20 years, the SpaceWorld 2000 Game Boy Advance

Nintendo Lot Check ROM Leak - Retro Reversing (Reverse Engineering)