Xbox -> Hacking -> ModChips:

There have been dozens of modchips produced for the Xbox. They all perform the same basic function, which is to load an alternate bios file. The stock bios has many security restrictions built in, such as not allowing unsigned code, backup media, or a different hard drive. Loading a hacked bios file allows users to override these security features.

List of Xbox modchips:
-Xenium

-X2

-X3

-SmartXX

-X-Chip

-X-Lite

-X-Changer

-X-BIT

-SpiderChip

-DuoX

-MuppetX

For legal reasons, modchips cannot be shipped with an alternate bios file. Because of this, Flashbios was developed from a legal Linux bios core. Flashbios has the basic function of booting the Xbox, and allowing you to reflash the chip with any bios you choose.