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Logging into an Ultrix 4.0 system
Type: Multi-tasking, multi-user Unix
Creator: Digital Equipment Corporation
Architecture: PDP-11, VAX, DECStation
Current Version: 4.5 for VAX and DECStation (1995)
Date Released: 1984

ULTRIX was DEC's official UNIX for VAX, PDP-11 and DECStation equipment.


ULTRIX-11 was available for the PDP-11 and can be obtained up to version 3.1 from TUHS. It will run under SIMH (and other PDP-11 emulators).


ULTRIX-32 for the VAX was derived from 4.2 BSD with some influences from SYSV and included support for specific DEC technologies. ULTRIX-32 is now available from TUHS. The latest version is 4.5 from 1995. It will run under the VAX simulator in SIMH.


Ultrix for DECStation is not available from TUHS. The latest version is 4.5 from 1995. This version will also run, (Including CDE + X11!} under GXemul.

Y2K compatability

It's been confirmed that 4.0 is NOT y2k compatable... Not many UNIX from the 1990's or prior are so it's really no surprise...

Running ULTRIX

SIMH will run Ultrix. Right now, only 4.0 on the microVAX II is currently known to work.

Installation instructions for SIMH can be found here.

Sourcecode for Ultrix can be found here