Paste the psxonpsp660.bin file directly into the system folder (do not hide it inside subfolders). Verifying the File in RetroArch To ensure the emulator recognizes the file: Open RetroArch. Go to > Information > Core Information .
It is the recommended BIOS for lr-pcsx-rearmed (used on Onion OS) and many other Libretro cores. How to Get psxonpsp660.bin BIOS Free psxonpsp660bin bios file free