1965 Bell Laboratories joins with MIT and General Electric in the development effort for the new operating system, Multics, which would provide multi-user, multi-processor, and multi-level
(hierarchical) file system, among its many forward-looking features.

1969 AT&T was unhappy with the progress and drops out of the Multics project. Some of the Bell Labs programmers who had worked on this project, Ken Thompson, Dennis Ritchie, Rudd Canaday, and Doug McIlroy designed and implemented the first version of the Unix File System on a PDP-7 along with a few utilities. It was given the name UNIX by Brian Kernighan as a pun on Multics.

1971 The system now runs on a PDP-11, with 16Kbytes of memory, including 8Kbytes for user programs and a 512Kbyte disk.

Its first real use is as a text processing tool for the patent department at Bell Labs. That utilization justified
further research and development by the programming group. UNIX caught on among programmers because it was designed with these features:
• programmers environment
• simple user interface
• simple utilities that can be combined to perform powerful functions
• hierarchical file system
• simple interface to devices consistent with file format
• multi-user, multi-process system
• architecture independent and transparent to the user.

1973 Unix is re-written mostly in C, a new language developed by Dennis Ritchie. Being written in this high-level language greatly decreased the effort needed to port it to new machines.

1974 Thompson and Ritchie publish a paper in the Communications of the ACM describing the new Unix OS. This generates enthusiasm in the Academic community which sees a potentially great teaching tool
for studying programming systems development. Since AT&T is prevented from marketing the product due to the 1956 Consent Decree they license it to Universities for educational purposes and to commercial entities.

1977 There are now about 500 Unix sites world-wide.

1980 BSD 4.1 (Berkeley Software Development)

1983 SunOS, BSD 4.2, SysV

1984 There are now about 100,000 Unix sites running on many different hardware platforms, of vastly different capabilities.

1988 AT&T and Sun Microsystems jointly develop System V Release 4 (SVR4). This would later be developed into UnixWare and Solaris 2.

1993 Novell buys UNIX from AT&T

1994 Novell gives the name "UNIX" to X/OPEN

1995 Santa Cruz Operations buys UnixWare from Novell. Santa Cruz Operations and Hewlett-Packard announce that they will jointly develop a 64-bit version of Unix.

1996 International Data Corporation forecasts that in 1997 there will be 3 million Unix systems shipped world-wide.