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BaseOS Install Guide

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Prashant Vaibhav edited this page Aug 15, 2026 · 6 revisions

What you need

  1. An SD card of 4GB or larger size
  2. A disk image flashing tool, e.g. Raspberry Pi Imager or if you're on the latest macOS, you can use my very simple drag-n-drop Flash Tool

How to install

If this is the first time you are installing BaseOS, do this:

  1. Download the correct BaseOS image for your device and unzip it. You will get an .img file about 1.5GB in size.
  2. Use RPI Imager to burn the image to an empty SD card.
    1. Go to "OS", then scroll down and click Use Custom.
    2. Select the .img file you downloaded and click Next.
    3. Select your SD card and write the image.
  3. When done, insert the SD card into the 1st SD card slot (usually on the left side) of your RG XX handheld, then power on.

BaseOS will boot up and expand to fill your SD card.

Once it shows ADD FRONTEND TO SD CARD, you are done with step 1.

Now it's time to install NextUI.

How to install NextUI?

First decide if you want to run everything from 1 card, or put NextUI on a 2nd SD card.

The two card setup is better because you can move your NextUI card between devices. If you don't care about that, feel free to install both on the same card.

You can always change your mind later and switch from 1-card to 2-card setup and vice versa. It's all flexible.

2-card setup

Just install NextUI on the 2nd SD card by unzipping the NextUI zip directly to the SD Card. See the NextUI install guide for Anbernic for details.

Insert this into the 2nd SD slot (usually on the right side) and power on (with BaseOS card in the 1st SD slot).

BaseOS will recognise that SD slot 2 has NextUI, and begin installing it. It takes about 1 minute, please be patient. Once done, it will launch NextUI. You're done, enjoy!

1-card setup

  1. After the first boot reaches ADD FRONTEND TO SD CARD, power off your device by holding the POWER button.
  2. Plug the SD card into your computer. You will see a BASEOS volume appear on your computer. This will be your NextUI partition.
  3. Unzip NextUI (h700 version) to this partition. If you want, you can also copy your Roms and Bios now.
  4. Eject the SD card and plug it back into your handheld and power it on.

BaseOS will then boot up, install NextUI and launch it.

Frequently Asked Questions (FAQ)

Q: I followed all the steps but BaseOS still says "ADD FRONTEND TO SD CARD"

A: If you followed the steps for 1-card setup, make sure you don't have anything plugged into the 2nd SD slot. Otherwise BaseOS will try to find NextUI on the 2nd card. Remove it and restart your handheld.

If you followed the steps for 2-card setup, did you forget to plug that into the 2nd SD slot? If yes then you did something wrong... try again.

Q: How do I switch between 1-card and 2-card setups?

A: BaseOS supports both 2 card and 1 card setups without requiring any reinstall:

  • If you plug a card in slot 2, it will start NextUI from there.
  • If you don't plug anything, it will start NextUI from the 1st card (BASEOS partition).

Q: I did 2-card setup but now I want to move it to a single SD card, how to do that?

A: Duplicate your NextUI setup to the BaseOS card.

  1. Plug your BaseOS card into your computer, you will see a BASEOS partition appear.
  2. Copy your entire NextUI card to this BASEOS partition. Make sure you also copy all hidden files and folders.
  3. Eject the BaseOS card, plug into your handheld and power it on.

Make sure you don't have anything in the 2nd SD slot otherwise BaseOS will prefer that.

Q: I did a 1-card setup but now I want to move to 2-card setup.

A: Just as above, copy your BASEOS partition contents to a newly formatted SD card.

How to update BaseOS

BaseOS is stable and updates are infrequent. But when I do release a new update, you don't need to reflash your card to install the update. Follow this:

  1. Download the .bosupd file for your device from the new release.
  2. Copy it onto the card your handheld reads — the BASEOS volume on a one-card setup, or your NextUI card on a two-card setup. Put it directly on the card root folder.
  3. Power the handheld on.

It shows UPDATING SYSTEM for about a minute, then restarts into the new version.

Will I lose any data when updating?

No. Updates are safe.

Your ROMs, saves, BIOS and settings are not touched. The update is also atomic, meaning a bad download cannot leave you with a handheld that won't start. If the new version fails to start, BaseOS returns to the previous one by itself.

Ideally you will delete the .bosupd file after successful update. But you can leave it on the card. Anything older than the version you are running is ignored.

If you copied an update and nothing happened, ask the handheld why over SSH:

baseos-update status

It lists every update file it can see and what it decided about each one.

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