On Board Computer (OBC) is a ruggedized computer designed to carry out various functions. OBC is a two module system based on Intel 80486 Microprocessor. Fault Tolerant Scheme in hot standby mode is employed to take care of bus-traffic. 

The 1553B bus of the OBC unit is organized over three 1553B Buses (B0, B1, B2) using BIU-61588 devices, configured as BC on B0, and B1 & B2 as RT (For main OBC).It uses MIL-STD-1553B interface to communicate with LC for which the standby OBC is configured in MT mode.OBC has its own internal clock through which RTC is generated. The entire software required by the OBC is PROM based.