A trove of information, papers and a presentation by Bob Eager of a very well-used and long-lived operating system, written by a tiny team out of necessity, used at Edinburgh and Kent universities.
Some nice mentions of patching microcode - faulty hardware being one of the difficulties.
Here’s the presentation as a video:
The Edinburgh Multi-Access System (EMAS) project started in 1966, and resulted in a real service to users from 1971, running on an ICL System 4/75. In 1976, work started on porting this to the ICL 2900 series, and a service was offered from October 1978. The University of Kent took up the system, and offered a service from late 1979. A further port was made to IBM and IBM clone systems, with the final service being closed in 1992.
There’s an effort to resurrect EMAS in simulation, relatively well-advanced.
Nice paper title (1977):
An Experiment In Doing It Again, But Very Well This Time
The famously named paper on the process of re-implementing EMAS on the ICL 2900.
I particularly recommend the collection of anecdotes:
Some EMAS and ICL 2900 related anecdotes are here:
(I was at Edinburgh Uni in 1983/4, and used IMP, but had no idea it was such an early language.)
via @drogon on anycpu