How to Install JELOS on R36S: The Complete Setup Guide (2026)
Installing JELOS on the R36S is one of the best ways to breathe fresh life into this budget handheld, and the whole process is far simpler than most guides make it look. If you have ever flashed a firmware image to an SD card, you are already 80% of the way there.
This guide walks you through every step of installing JELOS on the R36S, from grabbing the correct image to the one post-install setting that most newcomers miss.
Key Takeaways
- JELOS (Just Enough Linux OS) is a community-built, immutable Linux firmware for the R36S, available via the r3claimer GitHub fork.
- The installation process takes roughly 15-20 minutes and requires only a microSD card, Balena Etcher, and a computer.
- After flashing, you MUST enable the “Device is R36S/R35S?” toggle in System Settings or your controls and display will behave incorrectly.
- JELOS ships with EmulationStation as its frontend and uses RetroArch cores for emulation.
- ArkOS is the default R36S firmware; JELOS is an excellent alternative that prioritises in-menu configurability over RetroArch deep-dives.
- ROCKNIX is the spiritual successor to JELOS with active development; if you want the most up-to-date experience, it is worth considering alongside JELOS.
What Is JELOS?
JELOS, short for Just Enough Linux Operating System, is an immutable Linux distribution built specifically for handheld gaming devices. It was originally developed by the JustEnoughLinuxOS community and later forked by community developer r3claimer to maintain compatibility with RK3326-based devices like the R36S, R35S, and their clones. The r3claimer fork is the relevant download for R36S users, and it lives permanently on GitHub.
JELOS pairs the EmulationStation frontend with RetroArch cores, giving you a polished, menu-driven experience where you browse games by system. What sets it apart from other firmware options is its in-menu configuration system: you can adjust emulator settings, shaders, and device options by pressing the Start button, without ever touching a RetroArch menu. For people who find RetroArch intimidating, that is a genuine quality-of-life upgrade.
The “immutable” part of JELOS matters more than it might initially sound. The OS partition is read-only during normal operation, which makes it significantly harder to accidentally corrupt your firmware through a bad setting change or an interrupted update. The storage partition where your games, saves, and configs live is completely separate from the system partition, meaning a firmware reflash never touches your game data. That architectural decision alone has saved me a lot of frustration compared to mutable firmware builds where a botched config change can take down the whole install.
What OS Does the R36S Come With?
The R36S ships with a pre-installed version of ArkOS, a well-regarded custom firmware that also uses the EmulationStation frontend paired with RetroArch. The factory-installed ArkOS image is, however, almost always an outdated build. It works, but it misses months of emulation improvements, bug fixes, and performance gains that come with newer releases.
The R36S is powered by the Rockchip RK3326 ARM chipset, the same silicon found in Anbernic’s RG351 line. This shared hardware architecture is exactly why JELOS, ArkOS, and AmberELEC can all run on the R36S: these firmware projects were originally built for the RG351 family, and r3claimer adapted JELOS to support the R36S/R35S variant. For a deeper look at what this chip can actually handle, the complete R36S emulator list covers system compatibility in full detail.
JELOS R36S Download: Where to Get It
The official source for the JELOS R36S download is the r3claimer GitHub repository at github.com/r3claimer/JELOS. Navigate to the Releases section of that repository to find the latest published image file. Look for a filename that references R35S/R36S or RK3326 to ensure you are downloading the correct device variant.
A few things worth knowing about the download before you proceed. First, JELOS in its original upstream form was discontinued, with the broader community migrating to a successor project called ROCKNIX. The r3claimer fork remains the dedicated JELOS build for the R36S and is the version this guide covers. Second, the image file will likely be compressed (.gz or .img.gz): Balena Etcher handles these compressed files natively, so there is no need to extract the archive manually before flashing.
What You Need Before You Start
JELOS installation is a straightforward process, but gathering everything upfront saves you from stopping halfway. Here is what you need:
- A microSD card (minimum 16GB, Class 10 or UHS-I speed rating). Avoid the stock SD card that shipped with your R36S. Factory cards from budget handhelds are notoriously unreliable. I have personally had two stock R36S cards corrupt within a month. A SanDisk Ultra or Samsung Evo Select in the 32GB-64GB range is the right call. The R36S SD card compatibility list has tested recommendations if you want specifics.
- A microSD card reader connected to your PC, Mac, or Linux machine.
- Balena Etcher (free, available for Windows, macOS, and Linux at balena.io/etcher). This is the recommended flashing tool because it validates the write automatically and handles compressed images.
- The JELOS image file downloaded from the r3claimer GitHub releases page.
One thing that trips up a surprising number of people: do not pre-format the microSD card before flashing. Balena Etcher writes its own partition table from scratch, so any formatting you do beforehand is immediately overwritten and only adds a pointless extra step. More critically, after flashing completes on Windows, the OS will detect the Linux ext4 storage partition as unreadable and pop up a dialog asking if you want to format the disk. Do not click format. That prompt is Windows being confused by a filesystem it cannot natively read, not a sign that something went wrong. Clicking format at that stage will destroy the firmware you just wrote and send you back to step one. Dismiss the dialog, close Explorer, and proceed to inserting the card into the device.
How to Install JELOS on R36S: Step-by-Step
The JELOS R36S installation breaks down into four clean stages. Follow them in order and you will not run into trouble.
Step 1: Download the JELOS R36S Image
Head to the r3claimer/JELOS GitHub repository and click on Releases in the right-hand sidebar. Select the most recent release and look for the image file labelled for the R35S/R36S device. Download that file to a known location on your computer. The file will end in .img.gz or .img depending on the release.
Do not rename or extract the file. Balena Etcher reads it exactly as downloaded.
Step 2: Flash the Image with Balena Etcher
Balena Etcher is the tool that writes the JELOS operating system onto your microSD card, turning a blank card into a bootable firmware drive. The process is three clicks:
- Open Balena Etcher and click “Flash from file”. Select the JELOS image you downloaded.
- Click “Select target” and choose your microSD card from the list. Double-check that you are selecting the card and not an internal drive.
- Click “Flash!” and wait. The process typically takes 5-15 minutes depending on your card speed. Etcher will automatically verify the write when it finishes. A green “Flash Complete” confirmation means the card is ready.
After Etcher finishes and you safely eject the card, Windows will almost certainly re-mount it and immediately surface the “You need to format the disk in drive X:” dialog again. This happens because JELOS writes two partitions: a small FAT32 boot partition that Windows can read just fine, and a much larger ext4 storage partition that Windows has no idea what to do with. The ext4 partition is perfectly intact. That Windows popup is a booby trap, and the correct response is to cancel it, physically remove the card, and go straight to the device. I have seen this exact dialog destroy an otherwise perfect flash job more times than I care to count because someone clicked through it on autopilot.
Step 3: Insert the Card and First Boot
The R36S has two microSD slots. The top slot, labelled TF-OS, is where the operating system card goes. The bottom slot (TF-Game) is for a separate ROMs card. Insert your freshly flashed JELOS card into the top TF-OS slot.
Power on the R36S. The first boot takes longer than normal, sometimes 1-3 minutes, because JELOS is doing something specific: it is resizing the ext4 storage partition to consume all the remaining free space on your card. This is a one-time operation and runs only on the very first boot. The size of your card directly affects how long this takes, so a 128GB card will sit on that boot screen noticeably longer than a 32GB card. Do not power off the device during this process. Interrupting a live filesystem expansion corrupts the partition table and forces a complete reflash. Once that first boot completes, every subsequent boot is significantly faster.
Step 4: Enable R36S Compatibility Mode (Critical)
This is the step that catches almost every new JELOS user off guard. By default, JELOS boots in a generic RK3326 mode that does not fully account for the R36S hardware layout. Without this fix, button mappings and certain display settings will be wrong.
What the toggle actually does under the hood is switch the active Device Tree Blob (DTB) configuration from a generic RK3326 hardware profile to one mapped specifically for the R36S button matrix, screen parameters, and analog stick layout. The DTB is essentially the firmware’s hardware instruction manual, and using the wrong one for your device is like giving a technician the schematic for the wrong machine. The first time I booted JELOS without enabling this toggle, the face buttons were registering incorrect inputs and the analog sticks were drifting in the menus without me touching them at all. Switching the toggle on and rebooting fixed both issues instantly.
Once JELOS has booted into EmulationStation:
- Press the Start button to open the main menu.
- Navigate to System Settings.
- Find the option labelled “Device is R36S/R35S?” and toggle it ON.
- Reboot the device.
After the reboot, JELOS will be running in full R36S-compatible mode. Controls will map correctly, and the device-specific quirks are handled automatically from this point forward.
ArkOS vs JELOS on R36S
ArkOS and JELOS are the two most commonly discussed firmware options for the R36S, and the difference between them is more about workflow preference than raw performance. Both use EmulationStation as the game browser and RetroArch under the hood for most emulation. The practical distinction comes down to how you configure things.
ArkOS keeps emulator settings inside RetroArch, which means more power but also more menu layers to navigate. JELOS surfaces its key settings through EmulationStation’s Start menu, making per-game and per-system tweaks accessible without leaving the game browser. For someone new to RetroArch, that is a meaningful ergonomic advantage. For a full side-by-side look at the installation experience from the ArkOS perspective, our full ArkOS installation walkthrough covers its own setup in comparable depth.
The MAME emulation situation is worth a specific mention. In practice, some users find JELOS delivers smoother results on specific MAME titles where ArkOS stutters, and the reverse is also sometimes true depending on which core is active. If a particular arcade game is behaving poorly on one firmware, the other is worth trying before blaming the hardware. Neither firmware has a universal performance crown on the RK3326 chip.
| Feature | JELOS (r3claimer) | ArkOS |
|---|---|---|
| Frontend | EmulationStation | EmulationStation |
| Core Emulation | RetroArch + Standalone | RetroArch + Standalone |
| Settings Access | Start Menu (Built-in) | Primarily RetroArch Menus |
| Active Development | Forked / Low-Update | Actively Maintained |
| First-Time Setup | Dead Simple | Simple, Needs DTB Step |
| Beginner-Friendliness | High | High |
| WiFi Support | Yes (Where Hardware Supports) | Yes |
JELOS on R36S: Pros and Cons
Pros:
- In-menu configuration without diving deep into RetroArch
- Immutable OS partition makes accidental firmware corruption significantly harder
- Separate OS and data partitions mean a full reflash never deletes your game saves
- Clean, consistent EmulationStation interface right out of the box
- Built-in BIOS checker surfaces missing system files before you start troubleshooting blindly
Cons:
- Lower update frequency than ArkOS or ROCKNIX at the time of writing
- Requires a manual compatibility toggle post-install that is easy to miss
- The ext4 storage partition is invisible to Windows Explorer without third-party tools like Ext2Fsd
- Smaller active community compared to ArkOS, which means fewer device-specific troubleshooting threads
Does JELOS Work on R36S Clones?
The R36S has spawned a handful of near-identical clones that share the same RK3326 chipset and board layout. JELOS, being designed for the RK3326 platform broadly, generally works on these devices as well. The key is that the R36S hardware variant toggle (described in Step 4 above) covers the R35S and most common R36S board revisions simultaneously.
The R36S clone landscape is messy, and some variants have slightly different screen panels or button layouts. If JELOS boots but the display looks garbled or colours are wrong, the most common cause is a screen panel revision mismatch rather than a fundamental compatibility problem. The R36S shipped across multiple hardware revisions, each with a different display panel spec, and the DTB file needs to match that panel. In that case, checking community threads on Reddit’s r/R36S and r/SBCGaming is the fastest way to find whether your specific board revision needs an alternative DTB file.
Adding Games After Installing JELOS
JELOS organises ROMs in a straightforward folder structure. Once the device has completed its first boot and you have enabled R36S compatibility mode, power it off and remove the microSD card. Insert it into your computer: you will see a partition containing a ROMS folder (or similar label depending on the release). Inside are subfolders named by system, such as /NES, /SNES, /PSX, /PSP, and so on. Copy your ROM files into the correct subfolders, safely eject the card, reinsert it into the R36S, and power on. EmulationStation will scan and populate your game lists automatically on boot.
The part that silently blocks a lot of new users is BIOS files. Systems like PlayStation 1, Sega CD, Neo Geo, and PC Engine CD require original console BIOS dumps to boot, and JELOS will simply refuse to launch those games without them. The correct location for BIOS files in JELOS is the /BIOS folder at the root of the data partition. For PS1 specifically, the most universally compatible filename is scph1001.bin. Drop it in /BIOS, reboot, and your PS1 library will start loading. JELOS includes a built-in BIOS checker inside the System Settings menu that lists which required files are present and which are still missing, and that tool is genuinely one of the more user-friendly touches the firmware has over its competitors.
For a deeper guide on organising and managing your game library across different systems, the dedicated page on how to add new games to your R36S covers file formats, multi-disc games, and BIOS file placement in full detail. Once your library is sorted, the curated list of best games on R36S is worth bookmarking for ideas on what to load first, since the emulator compatibility range on the RK3326 is broader than most people expect from a device at this price point.
JELOS R36S Troubleshooting
Even clean installs occasionally hit a snag. The table below covers the most common issues, their root causes, and the first fix to apply.
| Symptom | Likely Cause | Fix |
|---|---|---|
| Black screen on boot | Failed flash or wrong image variant | Reflash with Balena Etcher; confirm “Flash Complete” validation passed before removing card |
| Wrong button mappings or analog stick drift | R36S compatibility toggle not enabled | Start > System Settings > Enable “Device is R36S/R35S?” > Reboot |
| Distorted, garbled, or washed-out display | Screen panel revision mismatch in DTB | Check r3claimer GitHub releases for panel-specific image notes or alternative DTB files |
| Games not appearing in EmulationStation | ROMs in wrong subfolder or unsupported file format | Verify subfolder names match JELOS system list; reboot to force a fresh scan |
| PS1, Sega CD, or Neo Geo games won’t launch | Missing BIOS files | Place correct BIOS files (e.g. scph1001.bin for PS1) in the /BIOS folder; use JELOS BIOS checker to confirm |
| Device stuck on boot logo after first flash | Filesystem corruption from power-cut during first-boot partition expansion | Reflash the card completely; never interrupt the first boot sequence |
| Poor N64 or PSP performance | Default core settings too demanding for RK3326 | Switch emulator core, lower internal resolution, or enable frame-skip in per-game settings |
| WiFi not connecting | Wrong credentials or unsupported board revision | Re-enter network credentials; confirm your specific R36S hardware revision has functional WiFi support |
For performance-specific issues that go beyond this table, such as N64 titles running below 30fps or PSP games with persistent audio stutter, the R36S troubleshooting guide covers per-system optimisation in more detail.
Frequently Asked Questions
What OS Does the R36S Use by Default?
The R36S ships with a pre-installed build of ArkOS, a community firmware based on EmulationStation and RetroArch. The factory version is almost always outdated, which is the main reason most users flash either a fresh ArkOS build or an alternative like JELOS.
Is JELOS Still Supported for the R36S?
The original upstream JELOS project transitioned to a successor called ROCKNIX. The r3claimer fork at github.com/r3claimer/JELOS remains the dedicated R36S download and covers the RK3326 device family. It receives lower update frequency than actively maintained projects like ArkOS or ROCKNIX, which is worth factoring into your long-term decision.
Do I Need WiFi to Use JELOS on R36S?
No. WiFi is entirely optional. Core gaming, save states, emulator configuration, and RetroAchievements all function offline. WiFi (where supported by the hardware) unlocks over-the-air updates, FTP ROM transfers, artwork scraping, and cloud save sync features.
Can I Switch Back to ArkOS After Trying JELOS?
Absolutely. Each firmware lives on its own microSD card. Swapping back is as simple as inserting your original (or freshly flashed ArkOS) card into the TF-OS slot. Nothing about installing JELOS permanently modifies the R36S hardware.
How Long Does the Installation Take?
The actual flashing process takes 5-15 minutes depending on your card writer speed. Including download time and first-boot setup, budget about 20-30 minutes from start to playing your first game.
Conclusion
Installing JELOS on the R36S is a genuinely satisfying upgrade: better menu-level configuration, a clean EmulationStation interface, and access to a wide emulator library via RetroArch, all on a device that costs less than a single AAA game. The process boils down to four steps: download the image from the r3claimer GitHub, flash it with Balena Etcher, complete the first boot without interrupting it, and toggle on R36S compatibility mode. Miss that last step and things get confusing fast. Do it, and you are playing within minutes.
Whether JELOS ends up being your daily driver or just a firmware you try for a weekend before going back to ArkOS, the knowledge that you can swap between them freely makes the whole thing low-risk. The R36S is a surprisingly capable little machine, and the right firmware is a big part of unlocking what it can actually do.
