Firmware & Customization Guide
Complete guide to choosing, installing, and customizing firmware for your R36S retro gaming handheld.
Quick Firmware Recommendations
Start here
Rocknix
Still shipping monthly, and usually boots without device-tree work
If your panel is unknown
Community ArkOS (frozen)
Panel Picker is still the least painful first boot — but retired, no further updates
ArkOS’s successor
dArkOS
R36S build exists; slower pace, last release March 2026
Understanding Firmware Options
The R36S ships with ArkOS, but several custom firmware options exist. They differ in what they decide for you and in how often they change under you — and they are no longer all in active development. ArkOS was retired in 2026; Rocknix is the one still shipping on a regular schedule. The sections below say where each one actually stands.
Stock ArkOS
What it is: ArkOS is a Linux distribution using Emulation Station as the front-end and RetroArch for most emulators. It's the default firmware on genuine R36S units.
Pros:
- Stable and widely supported
- Mature and well understood — though development ended in 2026, so no further updates
- Extensive documentation and community guides
- Compatible with most micro-SD cards
Cons:
- Stock pre-installed version is usually outdated
- Manual update process (requires downloading the RG351MP version and replacing device-tree files)
- No built-in Wi-Fi support (requires USB dongle)
When to choose it: Best for users who want the most stable, well-documented firmware with the largest community support.
Community-Maintained ArkOS (by AeolusUX)
What it is: A ready-to-flash ArkOS image specifically configured for the R36S, maintained by community member AeolusUX on GitHub.
Pros:
- Includes the correct device-tree blob (.dtb) files for all R36S screen panels
- Features "Panel Picker Mode" to automatically detect your screen type
- Simplifies installation—just flash and boot
- Integrates latest ArkOS improvements
Cons:
- Unofficial build (not from the original ArkOS maintainers)
- May lag slightly behind the latest official ArkOS releases
- Smaller user base than official ArkOS
When to choose it: Ideal for beginners who want ArkOS without the complexity of manually replacing .dtb files.
Rocknix (formerly JELOS)
What it is: The continuation of JELOS: that project was archived and its remaining developers carried the codebase forward under the Rocknix name, so this is the same lineage rather than a rival to it. Rocknix uses Emulation Station with integrated configuration options accessible from the Start button.
Pros:
- Actively maintained with regular updates
- Easier per-system and per-game emulator settings
- Integrated settings UI (no need to dive into RetroArch menus)
- Good performance optimizations
- Active community support
Cons:
- Slightly different interface may require adjustment
- Some advanced RetroArch features less accessible
- Still requires flashing via SD card
When to choose it: Best for users who want a more streamlined configuration experience and prefer integrated settings over RetroArch's complex menus.
JELOS — now Rocknix, not a separate choice
If a guide, video or forum post points you at JELOS, it is pointing at what is now Rocknix. JELOS was archived and its remaining developers carried the same codebase forward under the new name, so there is no fourth firmware to weigh here and no current JELOS release to download. Anything written about JELOS applies to Rocknix, allowing for everything that has shipped since.
This matters when you are reading older material. A 2023 comparison of “ArkOS vs JELOS” is a comparison of the same two projects covered above, and its conclusions about which one updates more often are now stale in both directions — the JELOS side kept going under another name, and the ArkOS side stopped.
AmberELEC
What it is: Custom firmware ported from Anbernic RG351 devices.
Pros:
- Alternative look and feel
- Some users prefer its interface
Cons:
- Not officially supported for R36S handheld
- No longer actively developed
- Requires manual configuration and renaming device-tree files
- Lacks recent performance optimizations
When to choose it: Only for advanced users who specifically want its unique features and are comfortable with manual configuration.
Firmware Comparison
Quick reference table to help you choose the right firmware for your needs:
| Feature | Stock ArkOS | Community ArkOS ✅ | Rocknix |
|---|---|---|---|
| Beginner Friendly | ⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ |
| Active Development | Retired 2026 | Retired 2026 | Yes |
| Community Support | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ |
| Panel Picker Mode | No | ✅ Yes | No |
| Ease of Configuration | ⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐⭐⭐ |
| Requires .dtb Replacement | ⚠️ Yes | ✅ No | No |
| Performance | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ |
| Recommendation | Frozen — fine if it works | Easiest install, frozen | Best for new users |
Our Recommendation
New to the R36S? Start with Rocknix. It is the only one of these still shipping regularly — monthly through 2026 — and it usually boots on an R36S panel without you having to swap device-tree files by hand.
Want ArkOS’s lineage with someone still working on it? dArkOS is the successor its author named when he retired ArkOS, and there is an R36S build. Set expectations on pace: its last release was March 2026 against Rocknix’s monthly, and it is essentially one maintainer. Support for the variants — R36H, R36 Plus, Max, Ultra — is in beta rather than finished.
Already running ArkOS and happy? Stay. It is frozen, not broken, and on hardware this well understood that is a legitimate place to be. The community build’s Panel Picker is still the least painful way to get a first boot on an unknown panel. Just know that nothing further is coming: no fixes, no core updates, and no issue tracker to report to.
How to Install or Update Firmware
Requirements
- A quality micro-SD card (16–128 GB, Class 10 or UHS-1)
- SD card reader for your computer
- Firmware image file (download from official sources)
- Flashing tool (Rufus, Win32DiskImager, Raspberry Pi Imager, or Balena Etcher—note: some guides discourage Etcher due to reliability issues)
- Backup of your original SD card (especially the BOOT partition and .dtb files)
Step-by-Step Installation Process
Step 1: Back Up Your Stock Card
Before making any changes, back up the entire stock micro-SD card to your computer. Pay special attention to the BOOT partition, which contains critical device-tree files (usually named rk3326-r35s-linux.dtb or rk3326-rg351mp-linux.dtb). If the stock card is corrupted or lost, these files can be downloaded from the community, but backing up is safer.
Step 2: Download Firmware
- For official ArkOS: Download the RG351MP version from the ArkOS website
- For community ArkOS: Download from the AeolusUX GitHub repository
- For Rocknix: Download from the Rocknix GitHub releases page
- For AmberELEC: On its GitHub page, though it is no longer updated. There is no separate JELOS download — that project is now Rocknix, above.
Step 3: Flash the Image
Insert your new micro-SD card into your computer's card reader. Use a flashing tool to write the downloaded image:
- Open Rufus (Windows), Win32DiskImager (Windows), or Raspberry Pi Imager (all platforms)
- Select your micro-SD card (double-check the drive letter to avoid overwriting the wrong disk!)
- Select the downloaded firmware image file
- Click "Write" or "Flash"
- Wait for the process to complete (5–15 minutes depending on image size and card speed)
Step 4: Replace Device-Tree Files (if needed)
This step is only necessary for official ArkOS. Community builds and Rocknix typically include the correct files.
- After flashing, the BOOT partition should appear as a readable drive on your computer
- Navigate to the BOOT partition
- Locate the
.dtbfile (usuallyrk3326-rg351mp-linux.dtb) - Replace it with the correct R36S device-tree file from your R36S backup or download from GitHub
- The file should be renamed to match the original name or as instructed in the firmware guide
Common .dtb files for R36S:
rk3326-r35s-linux.dtb(works for many units)rk3326-rg351mp-linux.dtb(standard for ArkOS RG351MP builds)- Community ArkOS includes multiple panel-specific .dtb files
Step 5: First Boot
- Safely eject the SD card from your computer
- Insert the SD card into the R36S's TF1/TF-OS slot (the right-side slot on your R36S)
- Power on the device
- Important: Allow 5–10 minutes for the OS to expand on first boot. The screen may stay black during this time—do not power off!
- After expansion completes, the Emulation Station interface should appear
Step 6: Configure Your Setup
Once booted:
- Set your language and timezone
- Configure screen brightness and volume
- If using a dual-card setup, insert your game ROM card into the TF2/TF-GAME slot and enable "Switch to Second SD for ROMS" in the Options menu
- If using a Wi-Fi dongle, connect it and configure your network
Dual-Card Setup (Recommended)
A dual-card configuration separates the operating system from your game library:
TF1/TF-OS Slot (system card): 16–32 GB card with firmware
TF2/TF-GAME Slot (ROM card): 64–512 GB card for games
Benefits:
- Firmware updates don't affect your game library
- Easier to test different firmware builds
- Simpler backup strategy
- Can swap ROM cards without touching the system
How to enable dual-card mode in ArkOS:
- Insert both cards
- Boot the device
- Press Start to access the main menu
- Navigate to Options → Switch to Second SD for ROMS
- Enable the option
- Reboot
- Your EASYROMS folder will now appear on the TF2 card
Customization Options
Changing Emulator Cores
Different games may perform better with different emulator cores. To change the core:
Per-System:
- Highlight any game in that system
- Press Start
- Navigate to "Emulator Settings"
- Choose your preferred emulator
- Changes apply to all games in that system
Per-Game:
- Highlight the specific game
- Press Start
- Navigate to "Edit This Game's Metadata"
- Change "Emulator" to your desired core
- Save
- This setting applies only to that specific game
Customizing Hotkeys
RetroArch hotkeys can be fully customized:
- During gameplay, press the hotkey button to open the RetroArch Quick Menu
- Navigate to Settings → Input → Hotkeys
- Assign new button combinations for functions like save state, load state, screenshot, fast-forward, etc.
- Save configuration to make changes persistent
Default R36S hotkeys on the ArkOS builds, which use FN as the hotkey button (ROCKNIX uses SELECT and a different set — the button mapping guide has both side by side):
- FN + R1: Save state
- FN + L1: Load state
- FN on its own: Fast-forward
- FN + A: Pause emulation
- FN + B: Reset the game
- FN + X: RetroArch Quick Menu
- FN + Start: Exit to menu
- Start + Select: Alternative exit combination (stock firmware)
Installing Themes
Emulation Station supports custom themes to change the appearance of the menu system:
- Download a theme package (many available on GitHub and retro gaming forums)
- Extract the theme folder
- Copy it to the
themesdirectory on your SD card - Reboot or restart Emulation Station
- Navigate to UI Settings → Theme Set
- Select your new theme
Popular themes include Carbon, Epic Noir, Art Book, and numerous custom community creations.
PortMaster (PC Game Ports)
PortMaster is a tool that installs native Linux game ports on the R36S. These are not emulated — they are the games' own code compiled for ARM, so they behave differently from anything in RetroArch.
Ports that suit this hardware well:
- Cave Story
- Doom series
- Duke Nukem 3D
- Quake series
- OpenBOR engine games
- Over 1,300 ports in total, added to regularly
PortMaster serves handhelds far more powerful than this one and its list is not filtered by device, so heavier entries — Half-Life or Stardew Valley, for example — are present but a much bigger ask of an RK3326. Check each port's own device notes. Our PortMaster guide covers the Wi-Fi requirement, the autoinstall folder for setting ports up without it, and which kinds of game hold up.
Installation:
- Download the PortMaster script from the official repository
- Copy it to your SD card's scripts folder
- Run PortMaster from the Ports section in Emulation Station
- Browse and install available ports
- Launch games directly from Emulation Station