[em500]

This is Unix V4 from 1973. The total number of installations world wide was around 20, all inside Bell Labs. There was no networking support at all, so security was mostly physical, i.e., office building security (though you could dial in with a modem). Multi-user support was a bunch of serial-line terminals. Pretty much everyone knew everyone else who was on the system.

[rst]

They were already mailing distribution tapes -- the software being run here was extracted off one of them (which had literally been lost in a store room for decades).