BIOS

A BIOS (Basic Input/Output System) is the firmware that ships baked into the original game console hardware — boot code, system menus, hardware initialization routines. Some emulators require the original BIOS to function correctly (PlayStation, Saturn, GBA in some cores) because games make calls into BIOS routines that need byte-accurate behavior. Distributing copyrighted BIOS images is illegal in most jurisdictions; users are expected to dump their own from hardware they own.