Wikipedia
Venix was a version of the Unix operating system for low-end computers, developed by VenturCom, a "company that specialises in the skinniest implementations of Unix".
A working version of Venix for the IBM PC XT was demoed at Comdex in May 1983. It was based on Version 7 Unix with some enhancements from BSD (notably vi) and custom inter-process communication mechanisms. In September 1984, Venix/86 Encore was released; it supported a number of early PC-compatibles, including the AT&T 6300, the Zenith 150, the (first) NCR PC, and the Texas Instruments Professional PC.
Venix 2.0, based on System III, ran on the DEC PRO-350 microcomputer (Venix/PRO), the DEC Rainbow 100 (Venix/86R) as well as PCs (Venix/86 and /286). It was released in 1984. From version 3.0, Venix was based on System V. A real-time version based in System V.3.2 was released for the 386 in 1990.
The last version Venix 4.2.1 based on UNIX System V Release 4.2 (UnixWare) was released in 1994. The workstation system included the real-time operating system, NFS and TCP/IP networking, X, OpenLook and Motif GUIs and the Veritas journaling File System ( vxfs). A development system included additionally an ANSI C compiler, a library of real-time functions, GUI development software, real-time development utilities, and selected industrial I/O device drivers.