No legitimate emulator developer includes this file with their software. You must dump it yourself from a PSP you own.
If you are verifying if your file is correct or trying to identify it, the specific MD5 hash for this BIOS is typically: c53ca5908936d412331790f4426c6c33 psxonpsp660.bin
: If you switch from an HLE BIOS to this file, your existing save states may break. You might need to delete old states to get the new BIOS to load correctly, though standard in-game memory card saves often remain compatible. No legitimate emulator developer includes this file with