Arthur's final computer and OS

I guess in "2001" Arthur tried to warn us about a
HAL9000 incident and loss of human life at the hands
of a computer. Many do not realize this actually
happened not long after his screenplay. The Therac-25
was a computer driven radiation therapy device that
came into use some years after "2001". A software
bug caused intense over-doses of radiation that killed
a number of patients. The bug could not be duplicated
by the manufacturer. It later turned out that to
duplicate the bug required experience with the computer.
This turned out to be dependent on the rate at which
instructions were typed in. Fascinating story, and one
which Arthur warned us about.

I do wonder what computer and OS was his last?

Dominic-Luc Webb