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RetroBIOS

Beetle PSX (Mednafen PSX)

Beetle PSX (Mednafen PSX) emulates Sony PlayStation. It reads 7 files, none of them required: it starts games without them.

About this profile
Detail Value
Type libretro
Classification Community fork
Source https://github.com/libretro/beetle-psx-libretro
Upstream https://mednafen.github.io/
Version 0.9.44.1, stated in libretro_options.h
Revision libretro/beetle-psx-libretro@7fea57a541ab
Profiled 2026-03-29
Profile YAML, JSON
Cores beetle_psx, mednafen_psx, mednafen_psx_hw, beetle-psx
Systems Sony PlayStation
Install this emulator's files

The installer finds your setup and its BIOS folder, then downloads only the files this emulator reads there and checks each one.

Open the Start menu. Type PowerShell and open it. Paste the line. Press Enter.

PowerShell
&([scriptblock]::Create((irm https://abdess.github.io/retrobios/i.ps1))) --emulator beetle_psx
Technical notes

Region-based BIOS selection: the core picks JP/NA/EU firmware based on disc region. SHA1 validated with warning on mismatch (does not block loading): libretro.c:744-756, 853-860. SHA1 and alternate filenames sourced from MAME (mame src/mame/sony/psx.cpp). The lists and the checksum search live in libretro.c:622-676,684-776. Override option allows using PSP, PS3, or OpenBIOS as region-free alternative. Embedded OpenBIOS (512KB) compiled into the binary serves as HLE fallback when no BIOS found. "Skip BIOS" option patches BIOS ROM but causes compatibility issues. Upstream Mednafen loads the same 3 region BIOS. Override BIOS and HLE fallback are libretro additions. Two BIOS geometries are accepted: the stock 512 KB kernel and the 1 MB SCPH-5903 part, selected by file size at load time (libretro.c:3467-3481). A 1 MB image switches Video CD from HLE to daughterboard emulation (libretro.c:6758). Reached through the BIOS path override only: the region name lists carry no SCPH-5903 entry, and the firmware scan compares against the region SHA1, so a 1 MB file never matches there (libretro.c:659-667). Mednafen rejects a BIOS that is not 524288 bytes (mednafen psx.cpp:1777), and the fork keeps that geometry as BIOS_SIZE_STD (libretro.c:1300), so this geometry is libretro only.

Files

Section titled “Files”

7 files: 0 required, 7 optional. 3 have an HLE fallback.

In this collection: 7 in repo and 0 missing.

Optional

Section titled “Optional”
FileStatusHash

scph5500.bin

SCPH-5500 (v3.0 09-09-96 J)

  • Aliases: SCPH5500.bin, SCPH-5500.bin
  • Without it the core logs 'Firmware is missing' and maps its built-in OpenBIOS (libretro.c:846-851, 3425-3511): the runs cited for required booted on OpenBIOS, the other regions' files refused.
Hashes, validation, source and more
  • On a failed check: warns and runs with the file
in repo HLE fallback both Region: JapanMD5 8dd7d5296a65

scph5903.bin

SCPH-5903 (System ROM Version 2.2 12/04/95 J), Video CD daughterboard

  • No code path opens this name: the Japanese name list and the SHA-1 scan look for scph5500.bin (libretro.c:768-776, 660-664). Copied as scph5500.bin it loads with a SHA-1 warning (libretro.c:854-861) and enables the Video CD daughterboard.
Hashes, validation, source and more
  • On a failed check: warns and runs with the file
in repo libretroMD5 81328b966e6d

scph5501.bin

SCPH-5501, 5503, 7003 (v3.0 11-18-96 A)

  • Aliases: SCPH5501.bin, SCPH-5501.bin, scph5503.bin, SCPH5503.bin, SCPH-5503.bin, scph7003.bin, SCPH7003.bin, SCPH-7003.bin, SCPH5501.BIN, SCPH-5501.BIN, SCPH5503.BIN, SCPH-5503.BIN, SCPH7003.BIN, SCPH-7003.BIN
  • Picked for REGION_NA: a SYSTEM.CNF serial whose third letter is U (SCUS, SLUS), a licence string naming America, and content whose region cannot be read while the region option stays on auto (libretro.c:2436-2438, 2279, 2330-2335, 3252-3266, 4517). Without it the core logs 'Firmware is missing' and maps its built-in OpenBIOS (libretro.c:846-851, 3425-3511): the runs cited for required booted on OpenBIOS, the other regions' files refused.
Hashes, validation, source and more
  • On a failed check: warns and runs with the file
in repo HLE fallback both Region: North America and Latin AmericaMD5 490f666e1afb

scph5502.bin

SCPH-5502, 5552 (v3.0 01-06-97 E)

  • Aliases: SCPH5502.bin, SCPH-5502.bin, scph5552.bin, SCPH5552.bin, SCPH-5552.bin
  • Without it the core logs 'Firmware is missing' and maps its built-in OpenBIOS (libretro.c:846-851, 3425-3511): the runs cited for required booted on OpenBIOS, the other regions' files refused.
Hashes, validation, source and more
  • On a failed check: warns and runs with the file
in repo HLE fallback both Region: Europe and OceaniaMD5 32736f17079d

psxonpsp660.bin

PSP embedded PS1 BIOS (region-free override)

  • Aliases: PSXONPSP660.bin
  • override_bios=1. Tried as psxonpsp660.bin, PSXONPSP660.bin, then PSXONPSP660.BIN. Falls back to region BIOS if not found.
Hashes, validation, source and more
  • SHA1: 96880d1ca92a016ff054be5159bb06fe03cb4e14
  • MD5: c53ca5908936d412331790f4426c6c33
  • Validation: sha1
  • Source: libretro.c:697-703
  • On a failed check: warns and runs with the file
in repo libretroMD5 c53ca5908936

ps1_rom.bin

PS3 embedded PS1 BIOS, first 512KB extracted (region-free override)

  • Aliases: PS1_ROM.bin
  • override_bios=2. Tried as ps1_rom.bin, PS1_ROM.bin, then PS1_ROM.BIN. Falls back to region BIOS if not found.
Hashes, validation, source and more
  • SHA1: c40146361eb8cf670b19fdc9759190257803cab7
  • MD5: 81bbe60ba7a3d1cea1d48c14cbcc647b
  • Validation: sha1
  • Source: libretro.c:705-711
  • On a failed check: warns and runs with the file
in repo libretroMD5 81bbe60ba7a3

openbios.bin

OpenBIOS (open-source PS1 HLE BIOS, region-free override)

  • Aliases: OPENBIOS.bin
  • override_bios=3. No SHA1 validation. Falls back to region BIOS if not found. Also embedded in binary as HLE fallback (libretro.c:2528-2530).
Source
in repo libretro-

Proof

Section titled “Proof”

Real runs that back this page (how they are made):

  • aliases of scph5501.bin: the core opened SCPH-5501.BIN, SCPH-5503.BIN, SCPH-7003.BIN, SCPH5501.BIN, SCPH5503.BIN, SCPH7003.BIN (records 1, 2, 3, 4, 5, 6).
  • hle_fallback of scph5501.bin: with no BIOS, it boots on the core's built-in BIOS (records 1, 2, 3, 4, 5, 6).
  • required of scph5500.bin: with scph5501.bin and scph5502.bin, it boots on the core's built-in BIOS (record).
  • required of scph5501.bin: with scph5500.bin and scph5502.bin, it boots on the core's built-in BIOS (record).
  • required of scph5502.bin: with scph5500.bin and scph5501.bin, it boots on the core's built-in BIOS (record).
  • validation of scph5501.bin: scph5501.bin: boots on scph5501.bin. scph5501.bin-zeros-524288: hangs. scph5501.bin-head-262144-of-scph5501.bin: hangs. scph5500.bin: shows a BIOS error. scph5502.bin: boots on scph5501.bin (record). With no BIOS, it boots on the core's built-in BIOS (record).

Next steps

Section titled “Next steps”
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Maintained by Abdess on GitHub. Report a problem.

Packs from release v2026.10.10, .

MIT for the tooling and metadata. BIOS and firmware files are third-party system software, preserved for personal backup, archival and interoperability.