February 20, 2026 Guide

R36S Dual SD Card Setup Guide

The R36S has two microSD card slots — TF1 for your firmware/OS and TF2 for your games library. Understanding how they work together saves you from common setup mistakes and lets you build a much larger game collection than a single card allows.

Understanding the Two SD Card Slots

The R36S ships with two microSD card slots labelled TF1 and TF2. They serve completely different purposes, and confusing them is one of the most common mistakes new R36S owners make.

TF1 (top slot) — System card: This is where your firmware lives. Whether you are running ArkOS, Rocknix, or the stock OS, TF1 holds the operating system, emulator configuration, and system files. This card is flashed with firmware using a tool like balenaEtcher — it is not formatted manually like a regular storage drive.

TF2 (bottom slot) — Games card: This is your game library card. It holds your ROMs, BIOS files, and save data. TF2 is optional but becomes essential once your game collection outgrows the space left on TF1 after the OS is installed.

The two-slot design exists for good reasons. Keeping the OS on a separate card from your games protects the firmware from corruption when you add or remove games. It also means you can swap entire game libraries by swapping TF2, and you can use a much larger card for games without paying for an unnecessarily large OS card.

Which Slot Is Which?

TF1 is the slot closer to the screen (top slot). TF2 is the bottom slot. Look at the label printed on the device next to the slots — it is marked directly on the R36S body.

Slot	Location	Purpose	Recommended Size
TF1	Top slot (near screen)	Firmware / OS	32–64GB (OS doesn't need more)
TF2	Bottom slot	ROMs, BIOS files, Saves	64GB–512GB (as large as needed)

Do You Need Two SD Cards?

No — you can run your R36S with only a card in TF1. ArkOS and most other firmware options automatically create a ROMS partition on TF1 during first boot. This partition is where your games go if you are using a single-card setup. Everything works fine this way.

Reasons to add TF2:

Your game library has grown larger than the remaining free space on TF1
You want to swap between different game libraries by swapping TF2
You want to reduce write wear on your OS card by keeping game transfers off TF1
You prefer having a dedicated large card (256GB, 512GB) purely for games

Reasons to stick with TF1 only:

Simpler setup — one card to manage, one card to back up
Works perfectly for smaller game collections (a few dozen games per system)
Fewer cards means fewer things that can go wrong or get lost

Beginner Recommendation

For most beginners: start with one card in TF1. Get comfortable with the device and your game collection first. Add TF2 later when your game library grows and you need the extra space.

Setting Up Your TF2 Games Card

When you are ready to add a second card, follow these four steps in order. Skipping steps or doing them out of sequence is the most common reason TF2 setup fails.

Step 1 — Format TF2 as exFAT

ArkOS expects TF2 to be formatted as exFAT. Do not use FAT32 and do not use NTFS — both will cause detection problems or prevent TF2 from being recognised correctly.

Windows:

Insert TF2 into your PC card reader
Open File Explorer, right-click the drive, and select Format
Set File system to exFAT
Leave Allocation unit size at default
Click Start and confirm

macOS:

Open Disk Utility (Applications → Utilities → Disk Utility)
Select your SD card from the left sidebar
Click Erase
Set Format to ExFAT
Click Erase to confirm

Linux:

Identify your card device with lsblk (for example, /dev/sdb)
Run: mkfs.exfat /dev/sdX (replace X with your actual device letter)
Do not run this on the wrong device — double-check before running

Important: Format TF2 Only

Format only TF2 this way. Never format TF1 manually — TF1 must be flashed with firmware using balenaEtcher, not formatted through File Explorer or Disk Utility. Manually formatting TF1 will erase your firmware and break your device until you reflash it.

Step 2 — Create the ROM Folder Structure on TF2

After formatting TF2, open it on your PC and create the required folder structure before adding any games. ArkOS expects TF2 to have the same folder layout as the ROMS partition on TF1.

At minimum, create a top-level ROMS/ folder. Inside it, create subfolders for each system you want to use:

ROMS/psx/ — PlayStation 1 games
ROMS/gba/ — Game Boy Advance games
ROMS/snes/ — Super Nintendo games
ROMS/nes/ — NES games
ROMS/gbc/ — Game Boy Color games
ROMS/md/ — Sega Mega Drive / Genesis games
ROMS/bios/ — BIOS files (PS1 BIOS, etc.)

The folder names are case-sensitive on Linux-based firmware. Use lowercase names to match what ArkOS expects. If you are unsure of the exact folder names, check what already exists in the ROMS partition on TF1 — TF2 must mirror that structure.

Easiest Approach

Copy the entire folder structure from your TF1 ROMS partition to TF2. Insert TF1 into your PC card reader, browse to the ROMS partition, and copy all the empty folders (without game files) to TF2. This guarantees the folder names and structure are identical and compatible.

Step 3 — Insert TF2 and Configure ArkOS

With TF2 formatted and the folder structure created, you are ready to connect it to the device:

Power off the R36S completely — do not insert TF2 while the device is running
Insert TF2 into the bottom slot (the TF2 slot)
Power on the device — ArkOS will detect TF2 automatically on first boot with the new card inserted
ArkOS may prompt you to expand or initialise TF2 — accept if prompted
Once EmulationStation has loaded, press Start to open the main menu
Navigate to System Settings → Storage Device
Select TF2 as your active storage device

After selecting TF2 as the storage device, ArkOS will look for ROMs on TF2 instead of (or in addition to) the TF1 ROMS partition.

Step 4 — Update Games List

Placing ROM files on TF2 is not enough on its own — ArkOS does not watch for new files automatically. After adding any ROMs, you must manually refresh the game list before games will appear in EmulationStation.

From EmulationStation, press Start to open the main menu
Go to Game Settings
Select Update Games List
Choose This System to update only the currently selected system, or All Systems to scan everything
Wait for the scan to complete — this can take a minute or two if you have a large library

Games Will Not Appear Without This Step

Games will NOT appear automatically after you copy ROMs to TF2. You must run Update Games List every time you add new ROMs. This trips up almost every new user — the ROMs are there, they just haven't been scanned yet.

Adding Games to TF2

Once TF2 is set up and recognised, there are two practical ways to copy games onto it.

Via USB Cable (Recommended for Large Libraries)

Transferring games wirelessly or via USB while the R36S is powered on avoids the need to physically remove TF2 every time you want to add games.

Connect the R36S to your PC using a USB-A to USB-C cable while the device is powered on
In ArkOS, go to EmulationStation → Start → Network Settings → Enable WiFi to set up Samba network sharing, which lets you browse and copy files over your local network from Windows Explorer or macOS Finder
Alternatively, check if your firmware version supports USB Mass Storage mode — this mounts TF2 as a drive letter on your PC via the USB cable directly

Samba (network transfer) is generally the most convenient method for ongoing use once it is configured, as you can drag and drop files without touching the cards.

Directly via SD Card Reader (Simplest Method)

The most straightforward approach — no network setup required:

Power off the R36S
Remove TF2 from the bottom slot
Insert TF2 into your PC card reader
Copy your ROM files to the correct folders (for example, ROMS/psx/ for PS1 games)
Safely eject TF2 from your PC
Reinsert TF2 into the R36S TF2 slot
Power on the device
Run Update Games List as described in Step 4 above

This method is the most reliable and works regardless of network configuration or firmware version. The only downside is physical wear from repeatedly removing and reinserting the card.

Save Files and TF2

When TF2 is active as your storage device, your save data lives on TF2 — not on TF1. This has some important implications:

Save files are stored on TF2, typically in the ROMS/saves/ folder or in system-specific subfolders within ROMS
If you remove TF2, your saves go with it — the R36S will not be able to load them until TF2 is reinserted
If you lose or damage TF2, you lose your save data for all games stored on it
BIOS files should also be on TF2 at ROMS/bios/ if TF2 is your primary storage, since ArkOS looks there for BIOS files when TF2 is active

Back Up TF2 Regularly

Back up your TF2 card regularly — it contains your game saves, not just your ROM files. Losing TF2 means losing your save data for every game you have played. Copy the entire TF2 contents to your PC periodically as a backup.

Troubleshooting Dual Card Issues

Most TF2 problems fall into one of three categories: the card is not detected, games are not showing up, or saves from TF1 are not accessible after switching. Here is how to resolve each.

TF2 Not Detected

Check the format: Confirm TF2 is formatted as exFAT, not FAT32 or NTFS. FAT32 is the most common cause of TF2 not being recognised by ArkOS.
Insert with power off: Always insert TF2 with the device powered off, then boot. Hot-inserting SD cards is not supported and can cause detection failures.
Re-seat the card: The TF2 slot can be finicky on some units. Remove TF2, blow gently on the slot to remove any dust, and reinsert firmly.
Test in a PC card reader: Insert TF2 into your PC. If your PC cannot read it either, the card itself may be faulty or incorrectly formatted.

Games Missing After Switching to TF2

Run Update Games List: This is the most common cause. After setting TF2 as the storage device, you must manually update the games list before any ROMs appear.
Check folder names are correct: Folder names are case-sensitive on Linux-based firmware. A folder named PSX is not the same as psx. Check against the TF1 ROMS partition for the exact names your firmware uses.
Check ROM location: ROMs must be in the correct subfolder. For example, PS1 ROMs belong in ROMS/psx/ — placing them in ROMS/PlayStation/ or the root ROMS/ folder will not work.

Saves Not Carrying Over from TF1 to TF2

Save files stored on TF1 do not automatically move to TF2 when you switch storage devices. ArkOS simply starts looking for saves in a different location. To carry your saves over:

Power off the R36S
Remove TF1 and insert it into your PC card reader
Browse to the ROMS partition on TF1 and locate the save folders (for example, ROMS/psx/saves/ or similar, depending on firmware version)
Copy those save folders to the same relative path on TF2
Safely eject both cards, reinsert into the R36S, and power on

After copying, your saves will be present on TF2 and the games will load them as normal.