Description:

Cromwell is a free, legal bios replacement for the Xbox. It is capable of
loading Linux from the Xbox's Hard Disk, and CDROM. It is not able to load
Xbox games, either originals or copies. It can be installed and used in
one of two ways.

* Flashed to a modchip - If selected, it will let you boot linux. If not
selected, it will load the original MS bios, so no functionality is lost.
* Flashed to the TSOP - this replaces the MS bios stored on the Xbox, and
makes it impossible to play games (whether original or not).

The advantage of the second method is that it makes it possible to
dedicate the whole harddisk to Xbox Linux.

Xromwell is a very similar program, built from the same sourcecode.
However, instead of being a bios, it is an XBE (XBox Executable), meaning
that it can be launched like other XBEs. It is not signed with the MS key,
which means you will need either a modchip with a bios that allows you to
run unsigned XBEs, or a softmod exploit, such as the UDE.

Cromwell/Xromwell also has a number of other functions, such as locking and
unlocking hard disks, and selecting video modes (PAL/NTSC switching).

See: http://www.xbox-linux.org/Cromwell_Manual for further reading.