Ken Shirriff @righto.com · Mar 29
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The Space Shuttle used a more advanced System/4 Pi computer called the AP-101B. A separate computer, the I/O Processor, provided 24 data buses to all parts of the Shuttle. These boxes still used individual TTL chips and magnetic core memory.

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Ken Shirriff · Mar 29

In 1991, the Space Shuttle upgraded its computer to the AP-101S, replacing two 60-pound boxes with one box. With five computers on the Shuttle, this change freed up 300 pounds for additional cargo. The CPU was implemented in three boards full of chips, much larger than the earlier 4 Pi boards.

Aaron Kimball · Mar 29

Was there any CPU / MCU running code anywhere? Or were they all 100% discrete logic?