"GPCs running together in the same GN&C (Guidance, Navigation and Control) OPS (Operational Sequence) are part of a redundant set performing identical tasks from the same inputs and
producing identical outputs. Therefore, any data bus assigned to a commanding GN&C GPC is heard by all members of the
redundant set (except the instrumentation buses because each GPC has only one dedicated bus connected to it). These
transmissions include all CRT inputs and mass memory transactions, as well as flight-critical data. Thus, if one or more GPCs in
the redundant set fail, the remaining computers can continue operating in GN&C. Each GPC performs about 325,000 operations
per second during critical phases. "
Acknowledgement: NASA Shuttle Reference Pages
