: Place in the system folder within your main RetroArch directory.

Here is the breakdown of what that file is and important context regarding its use:

With the right psxonpsp660.bin in your SEPLUGINS folder, you aren't just playing a game; you are mastering the hardware. Dust off your PSP, charge that battery, and let the nostalgia begin.

Unlike traditional BIOS files dumped from physical consoles (like SCPH-1001 or SCPH-5501), this version was optimized by Sony to run on mobile hardware.