The BIOS (Basic Input/Output System) is the low-level firmware that tells the PS2 hardware how to boot up, handle memory, and interact with controllers and discs.
Once you have the BIOS file, it acts as the "key" to unlock your games. Placement: In your emulator settings, you must point the BIOS Image directory to the folder containing your BIOS files [1, 26]. Configuration: fps2bios
You can legally extract PS1 and PS2 BIOS files from the official PS3 firmware available on Sony’s website [2]. Tools like the PS2/PS1 BIOS Extraction Guide Retro Game Corps The BIOS (Basic Input/Output System) is the low-level