From Halopedia, the Halo wiki
The ODST BIOS is firmware, designed to be the first code run by the ODST armor when activated. The initial function of the BIOS is to identify, test, and initialize system devices such as the heads-up display, VISR and other hardware.
The BIOS handles most of the armors software functions when initiated. Updates to the BIOS allow newer hardware to be supported and function. BIOS versions can be viewed though the ODST armors magnification system when no weapon is being held or no zoom-supported weapon is being held.
This BIOS version is equipped a Visual Intelligence System, Reconnaissance with low-light vision enhancement, which outlines hostile units in red, friendlies in green, weapons in blue, and objects of interest in yellow.
List of appearances