It was CMOS CPU that could be clocked to almost nothing. It was used in several cubesats and a few spacecraft--perhaps including the Hubble. https://en.wikipedia.org/wiki/...
These rudimentary chips have been a available in Silicon over Sapphire, and have been used in several spacecraft and satellites--including the Hubble. Oddly, it was the first CMOS chip, and can be clocked down to almost nothing.
Ref: https://en.wikipedia.org/wiki/...
IPS: https://github.com/amsat-dl/IP...