The rise and fall of IBM's 4 Pi aerospace computers: an illustrated history
Summary
The article provides an illustrated history of IBM's System/4 Pi avionics computers, tracing generation-to-generation from the TC/CP/EP line through Advanced System/4 Pi (AP, SP, CC, ML) and up to AP-102/VHSIC variants. It highlights how memory technology, standardization, redundancy, and rugged design shaped Space Shuttle and military avionics, with plenty of technical detail and vintage photos.