The Unix Tree

Welcome to the Unix Tree. Here you can browse the source code and manuals of various old versions of Unix. For every file, you can also find related files from other versions: this can help show how the different versions of Unix are related. Most of the Unix versions below come from the Unix Archive.

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Research Unix

These are the versions of Unix developed at Bell Laboratories, initially by Ken Thompson and Dennis Ritchie, later by many other of the researchers there.

PDP-7 Unix 1970-01
First Edition Unix 1971-11
Second Edition Unix 1972-06
Third Edition Unix 1973-02
Fourth Edition Unix 1973-11
Fifth Edition Unix 1974-06
Sixth Edition Unix 1975-05
Seventh Edition Unix 1979-01
Addenda to 7th Edition 1980-12


Originally set up to support Unix internally, the Unix Support Group eventually became Unix System Laboratories, and developed the System III and System V commercial versions of Unix.

PWB/UNIX 1.0 1977-07
32V Unix 1979-05
System III 1980-06
PDP-11 3+2 1983-01

Other Early Unixes

As Unix was distributed non-commercially in the mid-1970s, many other institutions took the system and modified it. Many of the changes from these early variants were fed back into the research version of Unix.

Mini-Unix 1976-12
Interdata 7/32 Port 1979-06
AUSAM 1979-10
V7M 2.1 1981-10

Early BSDs

The early BSDs, 1BSD and 2BSD, were collections of commands and libraries like the Pascal system, the ex editor and the C-shell. Later systems such as 2.8BSD through to 2.11BSD were complete, installable, 16-bit systems with kernel source.

The First BSD 1978-01
The Second BSD 1979-04
2.9BSD 1983-11
2.11BSD 1992-02

32-bit BSDs

3BSD was the first Unix to provide paged virtual memory. The 4BSDs went on to add features such as networking, the fast filesystem, vnodes & NFS, and they culminated in 4.4BSD-Lite which had been rewritten to contain no original Unix code.

3BSD 1980-03
4BSD 1980-10
4.1c BSD 1982-12
4.2BSD 1983-09
4.3BSD 1986-06
4.3BSD from UWisc 1987-01
4.3BSD Tahoe 1988-06
4.3BSD Reno 1990-06
The Net/2 Distribution 1991-06
4.4BSD 1993-06

Commercial Unixes

Many companies produced modified version of Unix, taking some or all of 32V, System III, System V, 4BSD, merging them and then value-adding to them.

Ultrix-11 3.1 1988-01

Unix Derivatives

Several systems started with Unix source code, but this was written out over time so that no original Unix code remains. The best known examples are OpenSolaris, FreeBSD, NetBSD and OpenBSD.

FreeBSD 5.3 2004-08
OpenBSD 4.6 2009-10
NetBSD 5.0.2 2010-02
OpenSolaris build 135 2010-03

Unix Clones

There have been many systems which implement the Unix system calls, library APIs and commands, but which did not include any original Unix source code. Here is a small selection.

Xinu 1987-01
Minix 1.1 1987-01
Minix 1.5 1989-11
Linux 0.96c 1992-07
Coherent 4.2 1994-12
Minix 2.0 1996-10
Linux 2010-04

Similarities between files are found using the ctcompare tool running in default mode. For each file, the list of similar files is given in descending order of the total number of similar token runs.

The Unix Tree website is (c) 2010, Warren Toomey.