Xbox Linux is a project that ported the Linux computer operating system to the Microsoft Xbox, a video game console. There is also a newer project for the Xbox 360, Free60. Because the Xbox uses a digital signature system to prevent the public from running unsigned code, one must either use a modchip, or find an alternative system for running unsigned code. Originally, modchips were the only option. However, it was later demonstrated that the TSOP chip on which the Xbox's BIOS is held may be reflashed. This way, one may flash on the "cromwell" BIOS developed by the Xbox Linux project (the name comes from a corruption of "clean room", alluding to the fact that it was developed entirely legally). Catalyzed by a large cash prize for the first team to provide the possibility of booting Linux on an Xbox without the need of a hardware hack, numerous software-only hacks were also found. For example, a buffer overflow was found in the game "007: Agent Under Fire", allowing the booting of a Linux loader ("xbeboot") straight from a save game.
The Xbox is essentially just a PC, with a custom 733MHz Intel Mobile Celeron processor, an 8GB (user-accessible. Actual capacity is 10GB) hard drive, 64MB of RAM (although on all earlier boxes this is upgradable to 128MB), and 4 USB ports (The controller ports are actually USB 1.1 with a modified connector). The specifications are enough to run several readily available Linux distributions, smoothly.
There are several Linux distributions available for the Xbox, such as "Xebian", an Xbox compatible version of Debian, and Gentoox, a similarly customized version of Gentoo. It is equally possible to produce your own distribution, requiring merely a recompilation of your kernel.
An Xbox with Linux can be a full desktop computer with mouse and keyboard, a web/email box connected to a TV, a server, router or a node in a cluster. One can either dual-boot or use Linux only; in the latter case, one can replace both IDE devices. One can also connect the Xbox to a VGA monitor. A converter may be needed to use keyboards/mice in the controller ports, however this is fairly easy to achieve because the Xbox uses the standard USB bus.
As of now only a few distributions (which one is not clear) of Linux will run on the 1.6 Xbox (the third newest version, including 1.6b). Xboxes with a modchip with the Cromwell bios installed can run more distributions than with only a softmod. This is mainly due to complications due to the new video chip used in V1.6 Xboxes that was developed exclusively by Microsoft and which has no source code available at this time, which causes major overscan on all four sides of the screen when a different kernel than the original is loaded.
One of the more popular ways of installing Xbox Linux is through a softmod, which does not require a modchip to use. The Xbox Linux softmod utilizes a save exploit found in the original run of MechAssault, Splinter Cell, and 007: Agent Under Fire. The method involves loading a hacked save file transferred to the Xbox's Hard Drive. When the save file is loaded, the MechInstaller (named for the most commonly used game for this method, MechAssault) is initiated. The Xbox Live option on the dashboard is replaced with the new Linux option after rebooting the system. Another softmod that can be used is the hotswap exploit which will unlock the Xbox hard drive long enough to allow one to modify it. So, if you have enough time on your hands and know what you're doing, you can remove the hard drive, put it into an actual computer, and partition the drive so that Linux can be used, but the Xbox system is still bootable (this means that you can still play the Xbox). Instructions and scripts can be found in the external links (Last link).