Sunday, August 29, 2010

Gmini 402 firmware loader

The Gmini 402 firmware loader is an utility which allows to temporarily load any firmware on the device, without flashing it. This means that after a reboot, the original firmware will load as it would normally do.

This utility loads any firmware from an AOS (firmware upgrade) file provided by Archos. These files are normally used to upgrade the firmware, and usually don't allow to downgrade to an older firmware version. Thanks to a lot of reverse engineering, I have reversed the AOS1 file format, allowing the development of the firmware loader.

To use it, download the zip archive from the link given below. Then extract it to the root of your Gmini 402. It will create a file named "firmware-loader.avi", and a "firmwares" directory. Then, download and put some AOS files into this "firmwares" directory.

Launch firmware-loader.avi from your Gmini 402, it will show you the list of the AOS files present in the "firmwares" directory. Pick one, validate with the square button, and a few seconds after, the firmware you picked will be loaded. Reboot your device to get back to the original firmware.

This utility is compatible (for now) only with the Gmini 402 (not CC), with firmware 1.3.11 (like any MediOS app).

Download it here:

Download AOS upgrades here (these links link directly to, so they may not work in the future, but will still be available through

Note: I can make a Gmini 402cc version of the firmware loader, I just need someone with a Gmini 402cc to run a program on it and give me the output. Let me know if you want it.

Note 2: While reversing Archos firmware, I found that Archos implementation of RSA is very slow (mainly because they don't use any "mod" optimization). In half a day, I implemented from scratch an RSA implementation which uses Barrett reduction, which is about 1,000 times faster.

Note 3: I'll publish the details of the AOS1 file format soon.


  1. hi there, i have the camcorder version of the 402. just let me know if you re still interested in trying it out.

    found your blog via archosfans forum, so i would contact via pm there, if you re interested.

  2. I'm going to contact you on archosfans forum, I guess your username there is Migge too.

    Thanks for helping.