As someone who has worked on nonstops for 35 years (and still counting!) it's nice to see them get a mention on here. I even have two at home, one a K2000 (MIPS) machine from the 90's and an Itanium server from a the mid 10's. I am pretty sure the suburbs lights dim when I fire them up :).

It's an interesting machine architecture to work on, especially the "Guardian 90" personality, and quite amazing that you can run late 70's based programs without a recompilation written for a CPU using TTL logic on a MIPS, Itanium or X86 CPU; not all of them mind you, and not if they were natively compiled. The note on Stratus was quite interesting for a long time the only real direct competitor Nonstop had in a real sense was Stratus. The other thing that makes these systems interesting is they have a unix like personality called "OSS" that allows you to run quite a bit of POSIX style unix programs.

My favourite nonstop story was in the big LA earthquake (89?) a friend of mine was working at a POS processor. When they returned to the building the Tandem machine was lying on its side, unplugged and still operating (these machines had their own battery backup). The righted it, plugged everything back in and the machine continued operating as though nothing happened. The fact that pretty much all the network comms were down kind of made this a moot point, but it was fascinating none the less. Pulling a CPU board, network board or disc controller or disc - all doable with no impact to transaction flow. The discs themselves were both mirrored and shadowed, which back in the day made these systems very expensive.