By no means a complete list, some significant Unix systems you'll not find in production today.
- Bell Labs Historic Unix
From PDP-7 or Unix V1 in 1969 to Seventh Edition or Unix V7 in 1979. Mostly by Ken Thompson and Dennis Ritchie.
Today, you can run some of the historical Unixes on a software simulator, faster than the original hardware,
thanks to the great work from The Unix Heritage Society. The emulator of choice
is Bob Supnik's SIMH which can emulate a DEC PDP-11 among many other
ancient machines.
- Early Academic, BSD
- Xenix
- Unix System III
- Ultrix
- Unix System V
- IRIX
- Unicos
- A/UX
- Tru64
- SCO OpenServer
- UnixWare