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

Gigaleak: Game Boy Advance BIOS and Game Boy Color Boot ROM

Nintendo DS Firmware 'Prototype' Reveals System's Unique Boot Up

Game Boy Advance / Useful Notes - TV Tropes

Altered GBA BIOS ? - The Independent Video Game

Nintendo GameCube Prototype From Space World 2000 Expo is

Another Nintendo leak uploaded online, features betas and source

Prototype GBA BIOS

Massive Nintendo Gigaleak Surfaces With ROMs, Canceled Games

Prototypes by system/Game Boy Advance - Hidden Palace

Nintendo GameCube Prototype From Space World 2000 Expo is

Prototypes by system/Game Boy Advance - Hidden Palace