Timeline: 40 Years Of Unix

Some milestones of the Unix operating system's four-decades-long history

Here are some milestones of the Unix operating system's four-decades-long history.


AT&T-owned Bell Laboratories withdraws from development of Multics, a pioneering but overly complicated time-sharing system. Some important principles in Multics were to be carried over into Unix.

Ken Thompson at Bell Labs writes the first version of an as-yet-unnamed operating system in assembly language for a DEC PDP-7 minicomputer.


Thompson's operating system is named Unics, for Uniplexed Information and Computing Service, and as a pun on "emasculated Multics." (The name would later be mysteriously changed to Unix.)


Unix moves to the new DEC PDP-11 minicomputer.

The first edition of the Unix Programmer's Manual, written by Thompson and Dennis Ritchie, is published.


Ritchie develops the C programming language.


Unix matures. The "pipe" is added to Unix; this mechanism for sharing information between two programs will influence operating systems for decades. Unix is rewritten from assembler into C.


"The UNIX Timesharing System," by Ritchie and Thompson, appears in the monthly journal of the Association for Computing Machinery. The article produces the first big demand for Unix.


Bell Labs programmer Mike Lesk develops UUCP (Unix-to-Unix Copy Program) for the network transfer of files, e-mail and Usenet content.


Unix is ported to non-DEC hardware, including the IBM 360.


Bill Joy, a graduate student at UC Berkeley, sends out copies of the first Berkeley Software Distribution (1BSD), essentially Bell Labs' Unix v6 with some add-ons. BSD becomes a rival Unix branch to AT&T's Unix; its variants and eventual descendents include FreeBSD, NetBSD, OpenBSD, DEC Ultrix, SunOS, NeXTstep/OpenStep and Mac OS X.


4BSD, with DARPA sponsorship, becomes the first version of Unix to incorporate TCP/IP.


Bill Joy co-founds Sun Microsystems to produce the Unix-based Sun workstation.


AT&T releases the first version of the influential Unix System V, which would later become the basis for IBM's AIX and Hewlett-Packard's HP-UX.


X/Open Co., a European consortium of computer makers, is formed to standardize Unix in the X/Open Portability Guide.


AT&T publishes the System V Interface Definition, an attempt to set a standard for how Unix works.


Rick Rashid and colleagues at Carnegie Mellon University create the first version of Mach, a replacement kernel for BSD Unix.


AT&T Bell Labs and Sun Microsystems announce plans to co-develop a system to unify the two major Unix branches.

Andrew Tanenbaum writes Minix, an open-source Unix clone for use in computer science classrooms.


The "Unix Wars" are under way. In response to the AT&T/Sun partnership, rival Unix vendors including DEC, HP and IBM form the Open Software Foundation (OSF) to develop open Unix standards. AT&T and its partners then form their own standards group, Unix International.

The IEEE publishes Posix (Portable Operating System Interface for Unix), a set of standards for Unix interfaces.


Unix System Labs, an AT&T Bell Labs subsidiary, releases System V Release 4 (SVR4), its collaboration with Sun that unifies System V, BSD, SunOS and Xenix.


The OSF releases its SVR4 competitor, OSF/1, which is based on Mach and BSD.


Sun announces Solaris, an operating system based on SVR4.

Linus Torvalds writes Linux, an open-source OS kernel inspired by Minix.


The Linux kernel is combined with GNU to create the free GNU/Linux operating system, which many refer to as simply "Linux."


AT&T sells its subsidiary Unix System Laboratories and all Unix rights to Novell. Later that year, Novell transfers the Unix trademark to the X/Open group.

Microsoft introduces Windows NT, a powerful, 32-bit multiprocessor operating system. Fear of NT spurs true Unix-standardization efforts.


X/Open merges with the OSF to form The Open Group.


Thompson and Ritchie receive the National Medal of Technology from President Clinton.


The Open Group announces Version 3 of the Single Unix Specification.

Sources: A Quarter Century of UNIX, by Peter H. Salus; Microsoft; AT&T; The Open Group; Wikipedia and other sources

Main story:Unix turns 40: The past, present and future of a revolutionary OS

This story, "Timeline: 40 Years Of Unix" was originally published by Computerworld.

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