Instead, it has:

Microsoft didn't just build one BIOS and forget it. Over 11 years of production (from Xenon to Winchester), the bootloaders were revised constantly to patch security holes. Here are the major "CB versions" modders care about:

Most emulators do not include these files because they are copyrighted by Microsoft. Users are typically expected to dump their own firmware from their physical consoles. 3. Modding and Custom Firmware (CFW)

You’ll need:

The console's operating system and subsequent bootloaders are stored on a flash memory chip called the NAND. This is where "firmware updates" or dashboard versions are installed.

Microsoft has historically issued suspensions for inappropriate language used in these profile bios. or are you looking for Xenia emulator setup instructions? Xbox 360 modding with 2 wires and 1 resistor - Facebook

(modifies boot flow)