R36S SD Card Guide: Format, Folders and File Types

On a two-slot R36S, the card in TF1 holds the firmware (the operating system) and the card in TF2, often marked GAME, holds your games, BIOS files and saves. You don't format the TF1 card: you flash a firmware image to it, and on ArkOS and dArkOS that image builds its own exFAT games partition, called EASYROMS, on first boot. For a separate games card, exFAT is the safe choice.

What trips most people up is folder names. ArkOS and dArkOS use short lowercase names such as psx, n64 and gba, while some seller cards use different ones. For the copy-and-paste steps, see how to add games to the R36S.

Which R36S SD card slot is which?

If your unit came with only a TF1 card, your games sit on that card's EASYROMS partition and TF2 stays empty. Single-slot units keep everything on one card.

One rule catches people out: according to the ArkOS wiki, once the firmware is set to use the second card for games, both cards must be inserted for it to boot.

What size and type of microSD card should you use?

• System card (TF1): the ArkOS and dArkOS install notes ask for at least 8 GB and strongly recommend 16 GB or more.
• Games card (TF2): size depends on your library. Cartridge games are small; PS1, PSP and Dreamcast disc images take most of the room. Setup guides commonly pair a 16 to 64 GB system card with a 128 GB games card.
• Brand: both wikis warn that no-name cards tend to fail quickly or refuse to boot, and recommend name brands such as SanDisk, Samsung or PNY from a trusted seller. Setup guides say the same about the unbranded cards bundled with many R36S units.

Neither wiki sets a minimum speed class.

How do you format an R36S SD card?

The system card (TF1): flash it, don't format it

1. Write the firmware image with an image-writing tool. Our dArkOS install guide covers which tools the projects recommend.

2. If Windows asks to format the card after flashing, click Cancel. Formatting wipes the install.

3. Don't resize the EASYROMS partition yourself. The first boot expands it to fill the card and converts it to exFAT. The ArkOS wiki warns that expanding it manually beforehand makes the first boot hang.

The games card (TF2)

1. Copy off anything you want to keep. Formatting erases the card.

2. Format it as exFAT. The ArkOS wiki accepts exFAT, ext4, FAT32 or NTFS and lists ext4, exFAT and NTFS as the faster options. exFAT is the one Windows, macOS and Linux can all open without extra software.

3. Give it its own label, such as ROMS. The dArkOSRE-R36 install guide warns against reusing the name EASYROMS, which can cause boot problems such as missing themes.

4. With the device off, insert the card in TF2 and power on. Open Options → Advanced → Switch to SD2 for Roms (on ArkOS, Options sits in the system list; dArkOSen calls it Enable SD2). The firmware creates the system folders but doesn't copy your games across.

5. Power off and copy your games into the new folders from your computer.

FAT32 also works, but it can't hold a single file over 4 GB, and the format tool built into Windows doesn't offer FAT32 for cards over 32 GB.

How are the folders organised, and why do the names differ?

On ArkOS and dArkOS, the games partition shows up as EASYROMS on your computer and as /roms on the device; a second games card appears as /roms2. Inside is one folder per system, plus support folders such as bios, tools and bgmusic.

Don't delete folders that look empty or unfamiliar. The ArkOS wiki notes that some, including the PSP and NDS folders, hold files those emulators need.

Folder names come from the firmware's own system list, not from any standard:

• ArkOS and dArkOS use the same names. The dArkOS emulator list repeats ArkOS's folder for every system.
• Some systems accept two names: megadrive or genesis, snes or sfc, nes or famicom.
• Seller cards can differ. Setup guides report stock cards that use names such as FC for the NES and MD for the Mega Drive.

How do you find the right folder for a system?

1. Look at the folders already on the games partition. The firmware creates them, so use those rather than making new ones.

2. Match the console to its short name using the table below. When a system has two possible folders, keep all its games in one.

3. Check the system's page on this site, for example PlayStation 1 or Game Boy Advance, for the file types and BIOS it needs.

4. Reboot and check the menu. EmulationStation hides systems whose folder is empty.

Which file types does each system accept?

These are the folders and extensions in the ArkOS emulator list, which dArkOS shares (upper-case extensions work too).

The R36S BIOS files guide explains the BIOS notes, and the R36S emulator list covers how well each system runs.

How do you set up multi-disc PS1 games with .m3u?

An .m3u file is a short text list of a game's discs, so the game shows up once in the menu.

1. Put every disc of the game in the psx folder. A subfolder per game is fine.

2. Create a text file named after the game, for example Metal Gear Solid (USA).m3u.

3. List one disc per line: the .cue file of each disc for CUE/BIN games, or the .chd file of each disc.

4. Save it and check the extension is .m3u, not .m3u.txt.

5. In the game, change discs from RetroArch's Quick Menu → Disc Control.

ArkOS can write these files for you: its Options section has a PS1 - Generate m3u files tool, which needs the word "Disc" in your file names. To hide the per-disc duplicates, open the PS1 list, press Start, go to UI Settings → Theme Configuration → File Extensions and tick only .m3u.

Should you use CHD, PBP or CSO to save space?

Usually, yes, though the saving varies by game.

• CHD is a lossless compressed disc format from MAME. It keeps every track, usually in noticeably less space, and turns a multi-file CUE/BIN game into one file. On ArkOS it works for PS1, Sega CD, PC Engine CD, Neo Geo CD, Dreamcast and PSP. MAME's chdman tool makes them (chdman createcd for CD games; the libretro docs note PSP CHDs need createdvd).
• PBP is a compressed PS1 format that came from the PSP. PCSX-ReARMed, the usual PS1 emulator, loads it.
• CSO is a compressed PSP ISO, read by PPSSPP.

One trade-off: the ArkOS wiki says uncompressed .gdi files usually give the best Dreamcast performance.

How do you back up the original R36S card?

Back up the card before you change anything. It holds the device files (DTB files) that match your exact board and screen, and community projects such as dArkOSRE-R36 ask for those files when your model isn't supported.

1. Shut down from the menu: Start → Quit → Shutdown.

2. Make a full image of the TF1 card. On Windows, the Read function in Win32 Disk Imager works; ticking Read Only Allocated Partitions keeps the image smaller. On macOS or Linux, a raw imaging tool such as dd does the job.

3. Copy the BOOT partition's .dtb files and boot.ini into a separate folder as well.

4. Copy your saves. On ArkOS-family firmware they sit next to the games, in each system folder.

5. Then move to a new name-brand card and keep the original as a fallback.

Common R36S SD card mistakes

• Not seeing EASYROMS on Windows. If only a small BOOT drive appears, Windows hasn't given the games partition a drive letter. Assign one in Disk Management.
• Copying from a Mac without checking. The ArkOS wiki warns that a Mac can add extra characters to files, a known reason games don't appear. macOS also leaves hidden files starting with ._; delete them if you see duplicate entries that won't launch.
• Hidden extensions on Windows, which turn game.cue into game.cue.txt. Turn on file name extensions in File Explorer.
• Pulling a card while the device is on. Shut down first.
• Losing track of saves when swapping cards. Saves stay with the games.

Still missing something? See the R36S troubleshooting guide and the ArkOS guide.

Sources: ArkOS wiki, ArkOS emulators and ports list, dArkOSRE-R36 firmware installation, libretro: disc images and CHD