Chris Johnson, Index
Space Shuttle General Purpose Computer (GPC) Case Study
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"(There are) 5 identical general-purpose computers aboard the orbiter control space shuttle vehicle systems. Each GPC is composed of two separate units, a central processor unit and an input/output processor. All five GPCs are IBM AP -101 computers. Each CPU and IOP contains a memory area for storing software and data. These memory areas are collectively re ferred to as the GPC's main memory.

The IOP of each computer has 24 independent processors, each of which controls 24 data buses use d to transmit serial digital data between the GPCs and vehicle systems, and secondary channels between the telemetry system a nd units that collect instrumentation data. The 24 data buses are connected to each IOP by multiplexer interface adapt ers that receive, convert and validate the serial data in response to discrete signals calling for available data to be transmitted or received from vehicle hardware."

Acknowledgement: NASA Shuttle Reference Pages

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