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# beetle_saturn - RetroBIOS

Type | libretro
Classification | community_fork
Source | https://github.com/libretro/beetle-saturn-libretro
Upstream | https://mednafen.github.io/
Version | v0.9.45.1
Profiled | 2026-03-24
Cores | mednafen_saturn
Systems | sega-saturn
Core ID | mednafen_saturn_libretro

Technical notes

Libretro port of Mednafen's Saturn emulation module, frozen circa v0.9.45.1 (2017) with some later backports. Region auto-detection reads the disc header and selects the matching BIOS. Manual override via beetle_saturn_region option.

InitCommon() returns false if the BIOS file is missing or not exactly 512 KB. Both region BIOS files are required for full region coverage.

KOF95 and Ultraman ROM carts are loaded when the cart type is set via core option or auto-detected from the internal game database.

Upstream Mednafen (1.32.x) has ST-V arcade board support (3 additional BIOS files) and bootable ROM cart support, both absent from this libretro port.

5 files | 2 required, 3 optional | 4 in repo, 1 missing

`sega_101.bin` -required, japan, asia-ntsc

- System: sega-saturn
- Size: 512.0 KB
- Validation: size
- Source: `mednafen/ss/ss.cpp:928-929,937-949`
- Platforms: batocera, emudeck, lakka, recalbox, retroarch, retrobat, retrodeck, retropie
- Saturn BIOS v1.01 (Japan). Used when region is JP or Asia NTSC.

`mpr-17933.bin` -required, north-america, europe, south-korea, asia-pal, brazil, latin-america

- System: sega-saturn
- Size: 512.0 KB
- Validation: size
- Source: `mednafen/ss/ss.cpp:930-931,937-949`
- Platforms: batocera, emudeck, lakka, recalbox, retroarch, retrobat, retrodeck, retropie
- Saturn BIOS (NA/EU). Used for all non-JP/Asia-NTSC regions.

`mpr-18811-mx.ic1` -optional

- System: sega-saturn
- Size: 2.0 MB
- Source: `mednafen/ss/cart.cpp:157-172, mednafen/ss/cart/rom.cpp:32-43`
- Platforms: batocera, lakka, recalbox, retroarch, retrobat, retrodeck, retropie
- KOF95 expansion ROM cart. Loaded when cart type set to KOF95.

`mpr-19367-mx.ic1` -optional

- System: sega-saturn
- Size: 2.0 MB
- Source: `mednafen/ss/cart.cpp:157-172, mednafen/ss/cart/rom.cpp:32-43`
- Platforms: batocera, lakka, recalbox, retroarch, retrobat, retrodeck, retropie
- Ultraman expansion ROM cart. Loaded when cart type set to Ultraman.

`satar4mp.bin` -optional, missing from repo

- System: sega-saturn
- Size: 256.0 KB
- Source: `mednafen/ss/cart.cpp:174-188, mednafen/ss/cart/ar4mp.cpp:120-159`
- Action Replay 4M Plus firmware. Unfinished in source (ar4mp.cpp:22-24), needs CPU UBC emulation. Cart type not exposed in core options.

Generated on 2026-03-25T14:56:43Z