This is what shipped in most 2001-2002 consoles. The most famous version is (the number refers to the kernel version, which is tied to the BIOS). This era is the most moddable because of a massive security flaw known as the "Font Hack."
Used in later "1.6" revision motherboards. This is the final official BIOS. It fundamentally changed how the console controls video output and, crucially, broke support for most "modchips" because it re-routed the LPC (Low Pin Count) bus. original xbox bios
The original Xbox was unique because it had a Hard Disk Drive (HDD) as a standard component. While the PS2 offered an optional HDD add-on (mostly for Final Fantasy XI), every Xbox had one. This meant the Xbox BIOS had a more complex job than most consoles: it had to manage a file system, handle dashboard updates, and interact with the HDD right from the boot sequence. This is what shipped in most 2001-2002 consoles
: Microsoft released several versions (e.g., 3944, 4034) ending with the final official retail BIOS Custom BIOS : Modders developed third-party replacements like X2 (Xecuter) This is the final official BIOS
: For consoles with a modchip or a flashed TSOP (Thin Small Outline Package) chip, the BIOS can be directly flashed or dumped using specialized software like XBlast [4, 8].