If the file you find has a matching MD5 sum, you can be confident it's the correct, unmodified BIOS.
emulation on RetroArch is by using the psxonpsp660.bin BIOS file. Historically, players had to hunt down regional BIOS files like scph5501.bin for North America, scph5502.bin for Europe, or scph5500.bin for Japan to avoid region locks. The file completely removes this hassle. Originally extracted from Sony’s official PlayStation Portable (PSP) firmware 6.60, this unified "omni-BIOS" is entirely region-free and explicitly optimized to deliver better performance and wider compatibility across all major emulation cores. Why psxonpsp660.bin is Better Than Traditional BIOS Files Psxonpsp660-bin Retroarch BETTER LINK
Disclaimer: This article is for educational purposes. We do not host or provide direct download links to copyrighted BIOS files. Please dump your own BIOS files from hardware you own. If the file you find has a matching