*Google* https://en.wikipedia.org/wiki/Tandem_Computers https://en.wikipedia.org/wiki/Tandem_Computers: 1974 (50y) (semi-dead) https://en.wikipedia.org/wiki/Q

*Google* https://en.wikipedia.org/wiki/Tandem_Computers https://en.wikipedia.org/wiki/Tandem_Computers: 1974 (50y) (semi-dead) https://en.wikipedia.org/wiki/QNX https://en.wikipedia.org/wiki/QNX: 1982 (42y) https://en.wikipedia.org/wiki/VxWorks https://en.wikipedia.org/wiki/VxWorks: 1987 (37y) https://en.wikipedia.org/wiki/GNU_Hurd https://en.wikipedia.org/wiki/GNU_Hurd: 1990 (34y) https://en.wikipedia.org/wiki/4690_Operating_System https://en.wikipedia.org/wiki/4690_Operating_System: 1993 (30y) (these run the self-service touchscreens at Costco's food section, IIUC) It's surprisingly hard to query for "graph intersection between earliest first release date and most recent release date" :(