alt Hacker NewsBack when I was in the USAF they told us 4 Pi was because it was essentially two IBM 360 mainframes in parallel. Probably BS but that was what we all thought.
Really happy to see this history lesson in any case, I had mostly forgotten about my experiences from the mid 90s.
You're right, that's BS :-) Yes, many of the 4 Pi systems were essentially IBM 360 mainframes; some were completely compatible, while others were more "inspired" by the 360. However, only the little-used EP/MP model was a multiprocessor system. As for the name, IBM made it clear that the name comes from 4 pi steradians in a sphere.
What 4 Pi systems did you work with, by the way? Do you have any interesting stories?