'Aerospace' usually covers 'space'. The shuttle used 5 IBM AP-101 flight computers (4 synch'ed voters for the core avionics software, 1 for independently written backup software). The AP-101 was designed to be a hi-rel computer for military use, so it's very much 'hardened' (including EMP protections), but not internally redundant. They were not cheap. Ken Shiriff has several articles about the hardware: https://www.righto.com/2026/03/ibm-4-pi-computer-history.htm...
