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UNIX Operating System – 1969 AD

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Ken Thompson (b. 1943), Dennis Ritchie (1941–2011), Malcolm Douglas McIlroy (b. 1932)

After Bell Labs decided to pull out of the Multics project, Bell computer scientists Ken Thompson, Dennis Ritchie, Malcolm McIlroy, and others decided to build a modern, streamlined operating system with a fraction of the resources that MIT and Honeywell were throwing into Multics.

Bell Labs had a five-year-old PDP-7 computer from DEC that wasn’t being otherwise used, so in 1969, Ken Thompson wrote an operating system for it that would implement the core Multics ideas, including a hierarchical file system with a root directory that could contain both files and other directories, a “shell” program that allowed the user to type commands that could support any number of directories and files within other directories, and the ability to expand the system with user-written commands.

By 1972, the system had a name—UNICS—a play of the word eunuch (a castrated man) and Multics. UNICS was a castrated Multics! Perhaps a bit childish, the name was changed to UNIX (nobody quite remembers by whom), and the new name stuck.

UNIX was rewritten into the newly invented C programming language in 1972. Although the minimalist operating system lacked many features found on more sophisticated operating systems, UNIX offered just enough features to let researchers and businesses develop their own software.

UNIX got a huge boost in 1983 when the University of California, Berkeley, added support for the internet’s transmission control protocol/internet protocol (TCP/IP) networking protocol to the operating system. Now any school or business that wanted to get on the internet could do so with a network connection and a computer running the Berkeley Standard Distribution (BSD) of UNIX, which also came with an email server, a mail client, and even games. Soon workstations were being created specifically for the purpose of running the operating system.

UNIX survives today as the operating system in the Apple Macintosh and the iPhone®.

SEE ALSO Utility Computing (1969), C Programming Language (1972), IPv4 Flag Day (1983), Linux Kernel (1991)

Photograph of Ken Thompson (sitting) and Dennis Ritchie (standing) at the PDP-11.

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