muOS ROM folder names: which folder each system goes in

On muOS you don’t have to copy a fixed folder layout. You make a folder inside ROMS, put your games in it, and muOS works out from the folder’s name which system it is and which emulator to use. That only works if muOS knows the name. This page lists the names it knows, how it reads them, and what to do with a system it doesn’t recognise.

Tested on: Anbernic RG40XXH · muOS 2601.0 Jacaranda. The list below is the one built into that version (assign.json, 378 names for 34 systems).

Where the folders go

• SD card 1: the ROMS folder at the top of the card.
• SD card 2 (if you have one): its own ROMS folder at the top.

Each system gets its own folder directly inside ROMS, for example ROMS/GBA. muOS doesn’t create these folders for you: on a new card, ROMS may be empty or hold only a few.

How muOS reads a folder name

When you open a folder in Explore Content for the first time, muOS:

1. turns the folder name into lower case,
2. removes spaces, -, _ and +,
3. looks the result up in its list. If it’s there, the folder gets that system and its default emulator.

So GBA, gba, Game Boy Advance and game-boy-advance all work: they become gba or gameboyadvance, which are on the list.

Some names you’d expect are not on the 2601 list, so those folders aren’t recognised:

• Game Boy Color (gameboycolor), although Game Boy and Game Boy Advance are. Use GBC.
• FBNeo and MAME, although the emulators are there. Use ARCADE or FBA.
• NDS and other systems without a name on the list (see below).

The list

The short name is the one we suggest: it’s on muOS’s list and easy to type. Any of the other names work as well.

System	Short name	Other names muOS recognises (a selection)
Nintendo Game Boy	GB	GAMEBOY, DMG, Game Boy
Nintendo Game Boy Color	GBC	GBCOLOR, NGBC (but not Game Boy Color, see below)
Nintendo Game Boy Advance	GBA	GBADVANCE, Game Boy Advance
Nintendo NES / Famicom	NES	FC, FAMICOM
Nintendo SNES / Super Famicom	SNES	SFC, SUPERNES, Super Famicom
Nintendo 64	N64	64, NINTENDO64
Sega Mega Drive / Genesis	MD	GENESIS, MEGADRIVE, GEN
Sega Master System	SMS	MS, MASTERSYSTEM
Sega Game Gear	GG	GAMEGEAR
Sega 32X	32X	SEGA32X, S32X
Sega Mega CD / Sega CD	SEGACD	MEGACD, SCD
Sega Dreamcast	DC	DREAMCAST
Sega Naomi / Atomiswave	NAOMI	ATOMISWAVE, AW
Sony PlayStation	PS	PSX, PS1, PLAYSTATION
Sony PSP	PSP	PPSSPP
NEC PC Engine / TurboGrafx-16	PCE	TG16, PCENGINE, TURBOGRAFX
NEC PC Engine CD	PCECD	TGCD, PCENGINECD
NEC SuperGrafx	SGFX	SUPERGRAFX
SNK Neo Geo	NEOGEO	NG
SNK Neo Geo CD	NEOCD	NGCD, NEOGEOCD
SNK Neo Geo Pocket / Color	NGP	NGPC, NEOGEOPOCKET
Arcade	ARCADE	FBA, MAME2003, CPS, FINALBURNNEO
Atari 2600	ATARI2600	2600, A2600, ATARI
Atari Lynx	LYNX	ATARILYNX
Commodore Amiga	AMIGA	AMIGA500
Commodore 64	C64	COMMODORE64
PC DOS	DOS	PC, MSDOS, DOSBOX
PICO-8	PICO8	PICO, FAKE08
ScummVM	SCUMMVM	SCUMM
Doom	DOOM	PRBOOM
Cave Story	CAVESTORY	NXENGINE
Ports (scripts)	PORTS	APPS, SCRIPTS
Books	BOOKS	BOOK
Video and music	MEDIA	VIDEOS, MUSIC, MOVIES

Folder names that are also emulator names (for example MGBA, SNES9X, DUCKSTATION, FLYCAST) are on the list too, and pick that system.

A system that isn’t on the list

Some systems muOS can run have no name on the 2601 list, for example Nintendo DS. Their folders are still shown, but muOS doesn’t know which emulator to use. Assign it once by hand:

1. Open the folder in Explore Content and highlight any game.
2. Press SELECT to open the content options, choose Core and press A.
3. Choose the system, then the emulator.
4. Press X to use it for every game in this folder (A sets it for this one game only).

muOS remembers the choice for that folder.

Games with several files

Disc games (PlayStation, Dreamcast, Sega CD…) often come as several files (.cue + .bin, .gdi + tracks). Keep each game in its own folder inside the system folder, for example ROMS/DC/Game Name/.

Putting games in the right folder over Wi-Fi

Our free app Wi-Fi Transfer sorts games for you. Tap Add games in your phone’s or PC’s browser and pick the files: a .gba file goes to ROMS/GBA, a .sfc to ROMS/SNES, and so on. If you already have a folder muOS knows for that system, for example ROMS/GBA, it uses that one. For file types that could belong to several systems (.zip, .bin, .iso, .chd), open the right folder first and upload into it.

Only use games you’re allowed to have, such as free homebrew. For ideas, see the best free homebrew games for the RG40XXH.

Troubleshooting

• The folder is there but games don’t start, or ask for a core: the name isn’t on muOS’s list. Rename the folder to a short name from the table, or assign the system by hand as above.
• A game starts with the wrong emulator: highlight it, press SELECT → Core and pick another one (press X to change the whole folder).
• Games don’t show at all: check they’re directly in the system folder (or in one game folder inside it), not in a .zip of a whole collection.

Summary

1. Make one folder per system inside ROMS, named with a short name from the table (GB, GBA, SNES, PS, PSP…).
2. Case, spaces, -, _ and + don’t matter.
3. Not on the list (for example Game Boy Color, NDS, FBNEO, MAME)? Rename it, or use SELECT → Core, then X for the whole folder.

Sources: the folder list built into muOS 2601.0 (assign.json on the handheld); how muOS reads folder names: MustardOS frontend source; Assigning a core to a directory (muOS community FAQ).

Questions? Email feedback@pocketkode.com.

PocketKode is not affiliated with muOS or Anbernic.