Third Edition Unix

Release Date: February, 1973
Released By: Bell Labs Research
Source Code: some source code is in the Unix Archive, browsable in the Unix Tree
Documentation: 3rd Edition man pages

The Third Edition of Unix was the last version with a kernel still written in assembly code, but is the first version to include pipes. More specifically, the Third Edition kernel targets the PDP-11/45 hardware including making use of protection and extended arithmetic features. For much of 1973, the existing Third Edition was maintained and improved, while the kernel was rewritten in C to become the Fourth Edition of Unix.

For the Third Edition of Unix we only have part of the C compiler, and the manual pages. Dennis Ritchie describes this version of the C compiler as follows:

“prestruct-c” is a copy of the compiler just before I started changing it to use structures itself. … [It] implements structures in a way that begins to approach their current meaning. Their declaration syntax seems to use () instead of {}, but . and → for specifying members of a structure itself and members of a pointed-to structure are both there.

The files currently listed as Second Edition under cmd and lib in the UNIX tree, V2 Sources, may represent code closer in character to the Third Edition, given the lack of Extended Arithmetic Element usage. See this email.

Changes include:

The following papers are carried over in SEE ALSO sections from the Second Edition in the manual:

The following papers are introduced in SEE ALSO sections:

For more information about Third Edition Unix, see The Evolution of the Unix Time-sharing System by Dennis Ritchie.