Dennis M. Ritchie

Ritchie studied at Harvard University and Summit High School. The recorded working language is English. The field of work recorded is computer science. Employment is recorded with Bell Labs. Works named in the authority record are The C Programming Language, ALTRAN, B, BCPL, Multics and Plan 9. Distinctions recorded are Turing Award, National Medal of Technology and Innovation, Harold Pender Award and IEEE Emanuel R.

• Name — Dennis Ritchie • Birth Name — Dennis MacAlistair Ritchie • Born — 9 September 1941 • Birthplace — Bronxville, New York, U.S. • Died — c. 12 October 2011 • Place of death — Berkeley Heights, New Jersey, U.S. • Education — Harvard University (BS) • Doctoral Advisor — Patrick C. Fischer • Known for — ALTRAN B BCPL C Multics Unix • Field — Computer science • Workplaces — Lucent Technologies Bell Labs • Awards — IEEE Emanuel R. Piore Award (1982) Turing Award (1983) National Medal of Technology (1998) IEEE Richard W. Hamming Medal (1990) Computer Pioneer Award (1994) Computer History Museum Fellow (1997) Harold Pender Award (2003) Japan Prize (2011) • Website — www.nokia.com/bell-labs/about/dennis-m-ritchie/

Dennis Ritchie was born in Bronxville, New York. His father was Alistair E. Ritchie, a longtime Bell Labs scientist and co-author of The Design of Switching Circuits on switching circuit theory. As a child, Dennis moved with his family to Summit, New Jersey, where he graduated from Summit High School. He graduated from Harvard University with degrees in physics and applied mathematics in 1963.

• Illustration — Ken Thompson (left) and Dennis Ritchie (right), in 1973 • Illustration — Version 7 Unix for the PDP-11, including Dennis Ritchie's home directory: /usr/dmr In 1967, Ritchie began working at the Bell Labs Computing Science Research Center. In 1968, he completed a draft of his PhD thesis on "Computational Complexity and Program Structure" at Harvard under the supervision of Patrick C. Fischer. However, Ritchie never officially received his PhD degree. In 2020, the Computer History Museum worked with Ritchie's family and Fischer's family and found a copy of the lost dissertation. During the 1960s, Ritchie and Ken Thompson worked on the Multics operating system at Bell Labs. Thompson then found an old PDP-7 machine and developed his own application programs and operating system from scratch, aided by Ritchie and others. In 1970, Brian Kernighan suggested the name "Unix", a pun on the name "Multics". To supplement assembly language with a system-level programming language, Thompson created B. Later, B was replaced by C, created by Ritchie, who continued to contribute to the development of Unix and C for many years. During the 1970s, Ritchie collaborated with James Reeds and Robert Morris on a ciphertext-only attack on the M-209 US cipher machine that could solve messages of at least 2000–2500 letters. Ritchie relates that, after discussions with the National Security Agency, the authors decided not to publish it, as they were told that the principle applied to machines still in use by foreign governments. Ritchie was also involved with the development of the operating systems Plan 9 and Inferno, and the programming language Limbo. As part of an AT&T restructuring in the mid-1990s, Ritchie was transferred to Lucent Technologies, where he retired in 2007 as head of System Software Research Department.

Ritchie created the C programming language and was one of the developers of the Unix operating system. With Brian Kernighan, he co-wrote the book The C Programming Language, which is often referred to as K&R after their initials. Ritchie worked together with Ken Thompson, who is credited with writing the original version of Unix; one of Ritchie's contributions to Unix was its porting to different machines and platforms. They were so influential on Research Unix that Doug McIlroy later wrote, "The names of Ritchie and Thompson may safely be assumed to be attached to almost everything not otherwise attributed." Nowadays, the C language is widely used in application, operating system, and embedded system development, and its influence is seen in most modern programming languages. C is a low-level language with constructs closely translating to the hardware's instruction set. However, it is not tied to any given hardware, making it easy to write programs on any machine that supports C. Moreover, C is a high-level programming language with constructs mapping to data structures in application software. C influenced several other languages and derivatives, such as C++, Objective-C used by Apple, C# used by Microsoft, and Java used in corporate environments extensively and by Android. Ritchie and Thompson used C to write Unix, which has been influential in establishing many computing concepts and principles that are adopted widely. In an interview from 1999, Ritchie clarified that he saw Linux and Berkeley Software Distribution (BSD) operating systems as a continuation of the basis of the Unix operating system, and as derivatives of Unix: I think the Linux phenomenon is quite delightful, because it draws so strongly on the basis that Unix provided. Linux seems to be among the healthiest of the direct Unix derivatives, though there are also the various BSD systems as well as the more official offerings from the workstation and mainframe manufacturers. In the same interview, he stated that he viewed Unix and Linux as "the continuation of ideas that were started by Ken and me and many others, many years ago."

• Illustration — Dennis Ritchie (right) with Doug McIlroy (left) in May 2011 Ritchie was found dead on October 12, 2011, at the age of 70 at his home in Berkeley Heights, New Jersey, where he lived alone. First news of his death came from his former colleague, Rob Pike. He had been in frail health for several years following treatment for prostate cancer and heart disease.

• B language • C language on which many succeeding languages and technologies are based. • Unix multiuser operating system. Several workalikes (commonly referred to as Unix-like systems) have been developed based on Unix's design. Some follow POSIX standards, again based on Unix. • Unix Programmer's Manual (1971) • The C Programming Language (sometimes referred to as K&R; 1978 with Brian Kernighan)

What the record establishes about Dennis M. Ritchie is recorded as having received Turing Award, National Medal of Technology and Innovation and Harold Pender Award. Ritchie is recorded at birth as Dennis MacAlistair Ritchie. The identifiers under which Dennis M. Ritchie may be traced in institutional catalogues.