The PSXONPSP660.bin file is widely considered the "Gold Standard" BIOS for PlayStation 1 emulation in RetroArch because it was originally an optimized, region-free BIOS included in Sony's PSP firmware 6.60. Why PSXONPSP660.bin is Better
The "Omni-BIOS": Why You Need PSXONPSP660.BIN for RetroArch If you’ve spent any time setting up Sony PlayStation emulation on Psxonpsp660-bin Retroarch BETTER LINK
Scroll down to the "Firmware" section. If you see "Present" next to the BIOS entry, you’re good to go. Core-Specific Settings : For cores like Beetle PSX The PSXONPSP660
File hosting churn – The psxonpsp660.bin is often hosted on: Some games will freeze on the "EA Games" or "Ubisoft" logo
You may also see files named psxonpsp660.pbp. The .bin version is a raw, uncompressed BIOS dump. RetroArch prefers the .bin format for direct loading, though it supports both. For the easiest path, stick with psxonpsp660.bin.