Earlier this year, people in many places wrote about the 40th anniversary of the moment Ken Thompson sat down and started to work on UNIX (which is actually in August). In fact, UNIX celebrates another birthday this year, even though on a slightly smaller scale.

In July 1974, exactly 35 years ago, Dennis Ritchie and Ken Thompson published the first version of their seminal paper The UNIX Time-Sharing System in the Communications of the ACM, Volume 17, Number 7, which is a revised version of a paper that has already been presented one year earlier at the Fourth ACM Symposium on Operating Systems Principles at the IBM Thomas J. Watson Research Center in Yorktown Heights, New York. Another updated version has been published later on in Volume 57, Number 6 of the Bell System Technical Journal , which is available on Dennis Ritchie's homepage. This paper received the ACM award for best paper in programming languages and systems in 1974.

Unix is a general-purpose, multi-user, interactive operating system for the larger Digital Equipment Corporation PDP-11 and the Interdata 8/32 computers. It offers a number of features seldom found even in larger operating systems, including

        i. A hierarchical file system incorporating demountable volumes,
        ii. Compatible file, device, and inter-process I/O,
        iii. The ability to initiate asynchronous processes,
        iv. System command language selectable on a per-user basis,
        v. Over 100 subsystems including a dozen languages,
        vi. High degree of portability.

This paper discusses the nature and implementation of the file system and of the user command interface.

In his paper Ritchie and Thompson already reported over 600 UNIX installations, but its final publication gave UNIX its first public exposure and a lot of visibility in the academic community. After its publication research labs and universities worldwide desired to give UNIX a shot and eventually took the computing world by storm.

The success of Unix lies not so much in new inventions but rather in the full exploitation of a care-fully selected set of fertile ideas, and especially in showing that they can be keys to the implementation of a small yet powerful operating system.

Due to its purity, simplicity and elegance UNIX has always been some kind of a programmers darling, or as Dennis Ritchie said, “constraint has encouraged not only economy, but also a certain elegance of design”. In his article Arc: An unfinished dialect of Lisp, Paul Graham said that UNIX won. Jeff Atwood expressed his opinion of UNIX on his blog as well: “I've been primarily a Windows developer since the early 90s, but over time, I've developed a grudging respect for Unix”.

Because we are programmers, we naturally designed the system to make it easy to write, test, and run programs. The most important expression of our desire for programming convenience was that the system was arranged for interactive use, even though the original version only supported one user. We believe that a properly designed interactive system is much more productive and satisfying to use than a “batch system”. More over, such a system is rather easily adaptable to non interactive use, while the converse is not true.

So, the question is: Would UNIX be where it is today, even without this paper? Or were Thompson's and Ritchie's incredible writing skills playing a large part as well? It certainly helped in the adoption of C.

One more thing

As we are talking about anniversaries, the Pragmatic Progammers are celebrating their 10th birthday today as well. From today on they will publish a free, monthly magazine called PragPub.

Therefore, happy birthday goes Ken Thompson and Dennis Ritchie ... AND the Pragmatic Programmers. Congratulations.

Labels: Miscellaneous, UNIX