R36S BIOS Files: Which Systems Need Them and Where They Go
Most R36S systems need no BIOS at all: NES, SNES, Mega Drive, Game Boy, N64 and PSP games run without one. The systems that do are mainly CD-based and arcade. Sega CD, PC Engine CD, Neo Geo and NAOMI games won't start without theirs, and PS1 and Dreamcast run better with one. On ArkOS and dArkOS, BIOS files go in the bios folder on the games partition (EASYROMS), or on the TF2 card if you've moved your games there.
File names must match exactly. Below are the names the emulators look for, taken from the ArkOS and dArkOS emulator list and the libretro documentation, with MD5 checksums so you can check files you dumped yourself. This site doesn't host, link to or say where to find BIOS files.
Which R36S systems need a BIOS?
| System | Need | File name(s) | Where and notes |
|---|---|---|---|
| PlayStation 1 | Recommended | scph1001.bin, scph5501.bin, scph7001.bin, scph101.bin or psxonpsp660.bin | bios folder. Any one is enough. |
| Sega CD / Mega-CD | Required | bios_CD_U.bin, bios_CD_E.bin, bios_CD_J.bin | bios folder. Each region's games need that region's file. |
| PC Engine CD / TurboGrafx-CD | Required | syscard3.pce | bios folder. syscard1.pce and syscard2.pce are optional extras. |
| Neo Geo | Required | neogeo.zip | Keep it zipped, in bios and in the neogeo folder. |
| Neo Geo CD | Required on ArkOS | neocd_f.rom, neocd.bin or uni-bioscd.rom | bios/neocd subfolder. See the note below. |
| Dreamcast | Recommended | dc_boot.bin (ArkOS also lists dc_flash.bin) | bios/dc subfolder. |
| Sega NAOMI | Required | naomi.zip | bios/dc subfolder. |
| Atomiswave | Required | awbios.zip | bios/dc subfolder. |
| Famicom Disk System | Required | disksys.rom | bios folder. |
| Game Boy Advance | Optional | gba_bios.bin | Used only when the mGBA option "Use BIOS file if found" is on. |
| Game Boy / Game Boy Color | Optional | gb_bios.bin, gbc_bios.bin | bios folder. |
| Nintendo DS | Optional | nds_bios_arm7.bin, nds_bios_arm9.bin, nds_firmware.bin | DraStic runs without them. |
| Sega Saturn | Optional | saturn_bios.bin | Most Saturn games are too slow on the R36S anyway. |
| Amiga | Needed | kick34005.A500, kick40068.A1200, kick33180.A500 | bios folder, used by Amiberry. |
| Atari Lynx | Sources differ | lynxboot.img | libretro lists it as required; ArkOS marks it optional. |
| Intellivision | Required | exec.bin, grom.bin | bios folder. |
| Arcade (FBNeo) | Some games | Board BIOS sets, such as pgm.zip for PGM games | arcade folder or bios. |
| NES, SNES, Mega Drive, N64, PSP, PC Engine | None | — | Mega Drive and Master System accept optional boot ROMs. |
Neo Geo CD note: the ArkOS list also names the LO ROM (000-lo.lo or ng-lo.rom) alongside the CD BIOS. Newer versions of the NeoCD emulator identify BIOS files by their contents and can fall back to a built-in BIOS, but the NeoCD project still calls an original BIOS the most compatible choice.
A few smaller systems depend on the emulator:
- Atari 5200: ArkOS lists 5200.rom and ATARIBAS.ROM. The current libretro Atari800 docs say the core runs without them, using built-in replacements.
- ColecoVision: ArkOS's default CoolCV emulator has its BIOS built in. Only the alternative blueMSX core needs coleco.rom.
- MSX and MSX2: the default blueMSX core needs the Databases and Machines folders from a full blueMSX installation, copied into
bios.
Where is the BIOS folder on ArkOS-based firmware?
- One card: EASYROMS →
bios. On the device, that's/roms/bios. - Two cards: after Switch to SD2 for Roms, use the
biosfolder on the TF2 games card (/roms2/bios). The ArkOS wiki says that in a two-card setup, all BIOS files go on the second card. - Subfolders: Dreamcast, NAOMI and Atomiswave files go in
bios/dc. The libretro Flycast docs say all its BIOS files must be in a folder nameddc. Neo Geo CD files go inbios/neocd. - Neo Geo: the ArkOS wiki recommends a copy of
neogeo.zipin bothbiosandneogeo, because Neo Geo ROM sets come in different formats. FBNeo checks the game's own folder first. - Seller cards and other builds: use the BIOS folder that's already on the card rather than creating a second one with different capitals.
Do BIOS file names have to match exactly?
Yes. The emulator looks for one exact name, and anything else is invisible to it.
- Capital letters count. ArkOS-family firmware runs on Linux. Its emulator list spells each extension twice, such as .cue and .CUE, because the system treats them as different names. Use the names exactly as listed. One wrinkle: libretro writes PSXONPSP660.bin in capitals and ArkOS writes psxonpsp660.bin. The scph names are lower case in both.
- Watch hidden extensions. Windows hides known extensions by default, so a file can end up named
scph1001.bin.bin. Turn on file name extensions in File Explorer. - Zip or not. Neo Geo, NAOMI, Atomiswave and arcade board BIOS files stay as .zip files. Single-file BIOS images such as
scph1001.binorsyscard3.pcemust not be zipped. - Region. A US Sega CD game needs
bios_CD_U.bin; a Japanese one needsbios_CD_J.bin.
How do you check a BIOS file with MD5?
An MD5 checksum is a fingerprint of a file. If your dump's fingerprint matches the published one, the dump is complete and correct.
1. Open a terminal in the folder that holds the file.
2. Run certutil -hashfile scph1001.bin MD5 on Windows, md5 scph1001.bin on macOS or md5sum scph1001.bin on Linux.
3. Compare the result with the table. Capital letters in the checksum don't matter.
| File | MD5 (libretro docs) |
|---|---|
| scph1001.bin | 924e392ed05558ffdb115408c263dccf |
| scph5501.bin | 490f666e1afb15b7362b406ed1cea246 |
| scph7001.bin | 1e68c231d0896b7eadcad1d7d8e76129 |
| scph101.bin | 6e3735ff4c7dc899ee98981385f6f3d0 |
| bios_CD_U.bin | 854b9150240a198070150e4566ae1290 |
| bios_CD_E.bin | e66fa1dc5820d254611fdcdba0662372 |
| bios_CD_J.bin | 278a9397d192149e84e820ac621a8edd |
| syscard3.pce | 38179df8f4ac870017db21ebcbf53114 |
| dc_boot.bin | e10c53c2f8b90bab96ead2d368858623 |
| disksys.rom | ca30b50f880eb660a320674ed365ef7a |
| gba_bios.bin | a860e8c0b6d573d191e4ec7db1b1e4f6 |
| exec.bin | 62e761035cb657903761800f4437b8af |
| grom.bin | 0cd5946c6473e42e8e4c2137785e427f |
A mismatch isn't always fatal. The libretro PCSX-ReARMed docs say any retail PS1 BIOS seems to work regardless of version or region, as long as it uses one of the expected names. Zipped BIOS sets such as neogeo.zip can't be checked this way, because a zip's checksum changes with how it was packed. Arcade tools check the files inside against the emulator's DAT file instead.
Where do BIOS files legally come from?
From hardware you own. The libretro docs put it plainly: RetroArch and libretro don't share copyrighted system files, and you must provide your own BIOS in line with your local laws. The ArkOS developer likewise says the project doesn't support or condone preloaded images or ROM packs.
- Dump your own. Dumping tools copy the BIOS of a console you own to a file. The method depends on the console.
- Check what came on the card. Many seller cards arrive with a filled
biosfolder. We can't tell you where those files came from. If you want to be sure, replace them with your own dumps. - Use our lists to verify, not to find. We publish names and checksums so you can check your own files. We don't host, link to or describe sources for BIOS files.
What are the symptoms of a missing BIOS?
| Symptom | Usual system | What to check |
|---|---|---|
| Game is in the list but drops back to the menu at once | Sega CD, PC Engine CD, Famicom Disk System | File name, region and folder |
| Every Neo Geo game fails | Neo Geo | neogeo.zip in bios and in neogeo |
| Some PS1 games black-screen or lose memory card saves | PS1 | A real BIOS instead of the built-in fallback |
| NAOMI games won't load in RetroArch | NAOMI | naomi.zip in bios/dc, and the region set to Japan |
| Neo Geo CD games won't boot | Neo Geo CD | Files in bios/neocd |
The PS1 row comes from the libretro docs: without a BIOS, PCSX-ReARMed uses a high-level emulation (HLE) BIOS, which can cause memory card problems in some games, Suikoden among them, and black screens in others. The NAOMI region tip comes from the ArkOS wiki: in RetroArch, go to Quick Menu → Options → Region → Japan.
RetroArch can also tell you what it sees. Its Information → Core Information screen lists the firmware files the loaded core looks for and marks each one present or missing. The libretro FBNeo docs warn that this check can report an FBNeo BIOS as missing even when the core finds it.
For other launch problems, see the R36S troubleshooting guide. Folder layout is in the R36S SD card guide, and system pages such as PlayStation 1, Neo Geo, Sega CD, PC Engine CD and Dreamcast list each system's needs.
Sources: ArkOS emulators and ports list, libretro BIOS guide, libretro PCSX-ReARMed, libretro Flycast
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