Fedora Linux
Fedora is the underlying operating system on the OLPC XO laptop. This is the Linux distribution (previously called "Fedora Core") developed by Fedora Project and sponsored by Red Hat.
Because it is the Linux base chosen by the OLPC on which to develop Sugar, it is a reference for any other Linux distribution attempting to run on the XO-1 hardware or present the Sugar UI on a conventional computer.
Fedora versions
Old builds including the 406.XX series were based on Fedora Core 6.
The transition to Fedora 7 happened in 2007 before the Trial 2 milestone (build 542).
So the operating system in the "ship.1" and "update.1" streams of releases was Fedora 7 , as you can see in the latest update.1 build log.
The 8.2.0 release was rebased on Fedora 9. Development efforts took place in the olpc3 stream but were merged into joyride as of build joyride-2072. Distro version migration nastiness records some of the changes made to the OLPC version of Fedora 7 that had to be reapplied to Fedora 9, and maybe in future rebasing efforts.
Language support
Fedora Core 6 uses the SCIM (Smart Common Input Framework) system to support multiple IMEs and keyboard layouts for multiple writing systems and languages. This includes Chinese, Japanese, Korean, and many other languages.
Installing Sugar
If you have a Fedora distribution running on a computer, you can install the Sugar environment that runs on the XO laptop.