NonStop

NonStop is a fault-tolerant computer architecture that Tandem Computers built from 1976: duplicated hardware and process pairs that take over for each other, so a broken component never stops the system. It ended up where downtime costs money by the second — bank clearing, stock trading, card and ATM networks, telecom. Compaq bought Tandem in 1997, HP took over in 2002, and the platform lives on at HPE, now on x86 rather than its own processors. The "no single point of failure" idea held for half a century.