What is a BIOS & Why Do You Need It? A BIOS (Basic Input/Output System) is a low-level firmware file that some consoles (PS1, PS2, Dreamcast, Neo Geo, etc.) require to boot games. It handles hardware initialization and disc authentication. RetroArch cannot "emulate" these files from scratch — you must provide them.
BIOS files do not "expire" or get "yearly updates" like antivirus definitions. The same PS1 BIOS from 1995 works today. A "2025 pack" is marketing — what matters is file integrity (MD5). retroarch bios pack 2025