Release Date: May 1975
Released By: Bell Labs Research
Source Code: v6src.tar.gz in the Unix Archive, browsable in the Unix Tree
Documentation: 6th Edition man pages

The Sixth Edition of Unix was released by Bell Laboratories in May 1975.

It was designed to run on the PDP-11s with 18-bit addressing such as the PDP-11/40, 11/45 and 11/70. The kernel's image size was around 29 Kbytes. This edition introduced the `Portable C Library' written by Mike Lesk, which would evolve into the Standard I/O library.

For more information about Sixth Edition Unix, see The Unix Time-sharing System: A Retrospective by Dennis Ritchie.