Kenneth Lane Thompson (born February 4, 1943) is an American pioneer ofcomputer science. Thompson worked atBell Labs for most of his career where he designed and implemented the originalUnix operating system. He also invented theB programming language, the direct predecessor to theC language, and was one of the creators and early developers of thePlan 9 operating system. Other notable contributions included his work onregular expressions and early computer text editorsQED anded, the definition of theUTF-8 encoding, and his work on computer chess that included the creation ofendgame tablebases and the chess machineBelle.
Since 2006, Thompson has worked atGoogle, where he co-developed theGo language. In 1983, he won theTuring Award with his long-term colleagueDennis Ritchie.[3] He is considered one of the greatest computer programmers of all time.[4][5][6]
Thompson was born inNew Orleans, Louisiana. When asked how he learned to program, Thompson stated, "I was always fascinated with logic and even in grade school I'd work on arithmetic problems in binary, stuff like that. Just because I was fascinated."[7]
Thompson was hired byBell Labs in 1966.[9] In the 1960s at Bell Labs, Thompson andDennis Ritchie worked on theMultics operating system. While writing Multics, Thompson created the Bon programming language.[10][11] He also created a video game calledSpace Travel. Later, Bell Labs withdrew from the MULTICS project.[12] In order to go on playing the game, Thompson found an oldPDP-7 machine and rewroteSpace Travel on it.[13] Eventually, the tools developed by Thompson became theUnixoperating system: Working on aPDP-7, a team of Bell Labs researchers led by Thompson and Ritchie, and includingRudd Canaday, developed ahierarchical file system, the concepts ofcomputer processes anddevice files, acommand-line interpreter,pipes for easy inter-process communication, and some small utility programs. In 1970,Brian Kernighan suggested the name "Unix", in a pun on the name "Multics".[14] After initial work on Unix, Thompson decided that Unix needed a system programming language and createdB, a precursor to Ritchie'sC.[15]
In the 1960s, Thompson also began work onregular expressions. Thompson had developed theCTSS version of the editorQED, which included regular expressions for searching text. QED and Thompson's later editored (the standard text editor on Unix) contributed greatly to the eventual popularity of regular expressions, and regular expressions became pervasive in Unix text processing programs. Almost all programs that work with regular expressions today use some variant of Thompson's notation. He also inventedThompson's construction algorithm used for converting regular expressions intonondeterministic finite automata in order to make expression matching faster.[16]
Throughout the 1970s, Thompson and Ritchie collaborated on the Unix operating system; they were so prolific onResearch Unix thatDoug McIlroy later wrote, "The names of Ritchie and Thompson may safely be assumed to be attached to almost everything not otherwise attributed."[17] In a 2011 interview, Thompson stated that the first versions of Unix were written by him, and that Ritchie began to advocate for the system and helped to develop it:[18]
I did the first of two or three versions of UNIX all alone. And Dennis became an evangelist. Then there was a rewrite in a higher-level language that would come to be called C. He worked mostly on the language and on the I/O system, and I worked on all the rest of the operating system. That was for thePDP-11, which was serendipitous, because that was the computer that took over the academic community.
Feedback from Thompson's Unix development was also instrumental in the development of the C programming language. Thompson would later say that the C language "grew up with one of the rewritings of the system and, as such, it became perfect forwriting systems".[18]
In early 1976, Thompson wrote the initial version of Berkeley Pascal at the Computer Science Division, Department of Electrical Engineering and Computer Science, UC Berkeley (with extensive modifications and additions following later that year byWilliam Joy, Charles B. Haley[20][21][22] and faculty advisorSusan Graham).
Thompson wrote a chess-playing program called "chess" for the first version of Unix (1971).[23] Later, along withJoseph Condon, Thompson created the hardware-assisted programBelle, a world championchess computer.[24] He also wrote programs for generating the complete enumeration ofchess endings, known asendgame tablebases, for all 4, 5, and 6-piece endings, allowing chess-playing computer programs to make "perfect" moves once a position stored in them is reached. Later, with the help of chess endgame expertJohn Roycroft, Thompson distributed his first results onCD-ROM. In 2001, theICGA Journal devoted almost an entire issue to Thompson's various contributions to computer chess.[23]
In 1983, Thompson and Ritchie jointly received theTuring Award "for their development of generic operating systems theory and specifically for the implementation of the UNIX operating system". His acceptance speech, "Reflections on Trusting Trust", presented the persistent compilerbackdoor attack now known as theThompson hack ortrusting trust attack, and is widely considered a seminalcomputer security work in its own right.[25] In 2023, the backdoor's annotated source code was published online.[26] The end of the acceptance speech consisted of criticism of journalists' positive coverage ofhackers, such asthe 414s.
A defence against the "Thompson hack" was developed by David A. Wheeler. It uses a technique called diverse double compilation to circumvent the hack by creating and comparingreproducible builds.[27]
Throughout the 1980s, Thompson and Ritchie continued revising Research Unix, which adopted a BSD codebase for the 8th, 9th, and 10th editions. In the mid-1980s, work began at Bell Labs on a new operating system as a replacement for Unix. Thompson was instrumental in the design and implementation of thePlan 9 from Bell Labs, a new operating system utilizing principles of Unix, but applying them more broadly to all major system facilities. Some programs that were part of later versions of Research Unix, such asmk andrc, were also incorporated into Plan 9.
Thompson tested early versions of theC++ programming language forBjarne Stroustrup by writing programs in it, but later refused to work in C++ due to frequent incompatibilities between versions. In a 2009 interview, Thompson expressed a negative view of C++, stating, "It does a lot of things half well and it's just a garbage heap of ideas that are mutually exclusive."[28]
In 1992, Thompson developed theUTF-8 encoding scheme together withRob Pike.[29] UTF-8 has since become the dominantUnicode encoding form for theWorld Wide Web, accounting for more than 90% of all web pages in 2019.[30]
In the 1990s, work began on theInferno operating system, another research operating system that was based around a portablevirtual machine. Thompson and Ritchie continued their collaboration with Inferno, along with other researchers at Bell Labs.[31]
In 1995, Thompson collaborated on music compression with Sean Dorward,based on original research work done by Jim Johnston, under the guidance of Joe Hall and Jont Allen.[32][33]
In 2004, he assisted in the implementation ofTurochamp, a chess programAlan Turing devised in 1948, before any computers existed that could execute it.[34]
He worked at Entrisphere, Inc. as afellow until 2006.
As of 2024[update] he works atGoogle, first as a Distinguished Engineer and later as a Google Advisor.[35] Recent work has included the co-design of theGo programming language. Referring to himself along with the other original authors of Go, he states:[18]
When the three of us [Thompson,Rob Pike, andRobert Griesemer] got started, it was pure research. The three of us got together and decided that we hated C++. [laughter] ... [Returning to Go,] we started off with the idea that all three of us had to be talked into every feature in the language, so there was no extraneous garbage put into the language for any reason.
In 1983, Thompson and Ritchie jointly received theTuring Award "for their development of generic operating systems theory and specifically for the implementation of the UNIX operating system". In his acceptance speech, "Reflections on Trusting Trust", Thompson outlined an attack in the form of acompiler backdoor that has been referred to as theThompson hack or thetrusting trust attack, and is widely considered a seminalcomputer security work in its own right.[25]
In 1997, both Thompson and Ritchie were inducted asFellows of theComputer History Museum for "the co-creation of the UNIX operating system, and for development of the C programming language".[38] In 2024, he recorded an extensive oral history for the museum.[39]
On April 27, 1999, Thompson and Ritchie jointly received the 1998National Medal of Technology from PresidentBill Clinton for co-inventing the UNIX operating system and the C programming language which together have "led to enormous advances in computer hardware, software, and networking systems and stimulated growth of an entire industry, thereby enhancing American leadership in the Information Age".[40]
Ken Thompson is married and has a son.[43][23] He was a user ofApple products but later switched toRaspberry Pi OS due to issues he faced with Apple products.[44]
^"Thesis Students".Elwyn Berlekamp's Home Page. University of California, Berkeley Department of Mathematics. Archived fromthe original on Oct 21, 2021.
^Thompson, K. L. (1969)."Bon User's Manual"(PDF).Multics History Project. Multics Documents: MIT Computer Science & Artificial Intelligence Lab. p. 1. Archived fromthe original(PDF) on Feb 14, 2021. RetrievedMar 18, 2021.
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