The origins HP NonStop date back to 1974 when Jimmy Treybig founded Tandem Computers.

His mission was to create the Tandem NonStop: the most reliable and fault tolerant computer in the world. He then planned to sell his NonStop computers to banks, payment processors, ATM networks, stock exchanges, telecom firms and any company/government for which computer server downtime and data loss was simply not acceptable.

The Tandem name came from the fact that Jimmy's servers had two of everything, so if a fault occurred in one component, the server would automatically switch to its twin component without missing a beat.

In 1976, the first customer NonStop was shipped to Citibank and many more customers were to follow. In 1997 Tandem was bought by Compaq and in 2001 Compaq merged with HP, paving the way for today's ultra high performance HP NonStop machines.

Further reading is available HP's website, on Wikipedia for Tandem and also on this HP NonStop entry on Wikipedia.