It acts as the bridge between the emulator and the game code. Without it, many games will not boot or will suffer from save-file corruption.
| BIOS Filename | Region | MD5 Checksum (common) | Notes | |---------------|--------|------------------------|-------| | scph1001.bin | USA (NTSC) | 924e392ed05558ff84611551b07d044e | Original PSX; highest compatibility for early titles | | scph5501.bin | USA (NTSC) | 8dd7d5596c0307e2f8f364ff71bfc4f5 | Recommended for most games | | scph5502.bin | PAL (Europe) | 5dfacf1d4c6f37c92b6ee4ac6d84c1f5 | Required for PAL-only titles | | scph5500.bin | Japan (NTSC) | 8d5e4b5cfc01b75b1f5c5dafea8f6f2d | Japanese region games | | scph1000.bin | Japan (NTSC) | - | Very early BIOS; some timing issues | | scph7001.bin | USA (NTSC) | - | PSOne BIOS; identical to 5501 for emulation | Epsxe 1.9.25 Full HOT- Bios-plugins-memory Card