Dennis MacAlistair Ritchie (September 9, 1941 – October 12, 2011) was an American

computer scientist A computer scientist is a person who is trained in the academic study of computer science. Computer scientists typically work on the theoretical side of computation, as opposed to the hardware side on which computer engineers mainly focus (a ...

. He is most well-known for creating the

C programming language ''The C Programming Language'' (sometimes termed ''K&R'', after its authors' initials) is a computer programming book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally designed and implemented the language, as well a ...

and, with long-time colleague

Ken Thompson Kenneth Lane Thompson (born February 4, 1943) is an American pioneer of computer science. Thompson worked at Bell Labs for most of his career where he designed and implemented the original Unix operating system. He also invented the B programmi ...

, the

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, ...

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

and B programming language. Ritchie and Thompson were awarded the

Turing Award The ACM A. M. Turing Award is an annual prize given by the Association for Computing Machinery (ACM) for contributions of lasting and major technical importance to computer science. It is generally recognized as the highest distinction in compu ...

from the ACM in 1983, the Hamming Medal from the

IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operati ...

in 1990 and the

National Medal of Technology The National Medal of Technology and Innovation (formerly the National Medal of Technology) is an honor granted by the President of the United States to American inventors and innovators who have made significant contributions to the development ...

from President Bill Clinton in 1999. Ritchie was the head of

Lucent Technologies Lucent Technologies, Inc. was an American multinational telecommunications equipment company headquartered in Murray Hill, New Jersey. It was established on September 30, 1996, through the divestiture of the former AT&T Technologies business u ...

System Software Research Department when he retired in 2007. He was the "R" in

K&R C C (''pronounced like the letter c'') is a general-purpose computer programming language. It was created in the 1970s by Dennis Ritchie, and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of ...

, and commonly known by his

username A user is a person who utilizes a computer or network service. A user often has a user account and is identified to the system by a username (or user name). Other terms for username include login name, screenname (or screen name), accoun ...

dmr.

Personal life and career

Dennis Ritchie was born in

Bronxville, New York Bronxville is a Administrative divisions of New York#Village, village in Westchester County, New York, Westchester County, New York (state), New York, United States, located approximately north of Midtown Manhattan. It is part of the Administ ...

. His father was Alistair E. Ritchie, a longtime

Bell Labs Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mul ...

scientist and co-author of ''The Design of Switching Circuits'' on

switching circuit theory Switching circuit theory is the mathematical study of the properties of networks of idealized switches. Such networks may be strictly combinational logic, in which their output state is only a function of the present state of their inputs; or ma ...

. As a child, Dennis moved with his family to

Summit, New Jersey Summit is a city in Union County, in the U.S. state of New Jersey. The city is located on a ridge in northern-central New Jersey, within the Raritan Valley and Rahway Valley regions in the New York metropolitan area. At the 2010 United State ...

, where he graduated from Summit High School. He graduated from

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of highe ...

with degrees in

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which ...

and

applied mathematics Applied mathematics is the application of mathematical methods by different fields such as physics, engineering, medicine, biology, finance, business, computer science, and industry. Thus, applied mathematics is a combination of mathemati ...

In 1967, Ritchie began working at the Bell Labs Computing Sciences Research Center, and in 1968, he defended his PhD thesis on "Computational Complexity and Program Structure" at Harvard under the supervision of

Patrick C. Fischer Patrick Carl Fischer (December 3, 1935 – August 26, 2011) was an American computer scientist, a noted researcher in computational complexity theory and database theory, and a target of the Unabomber.. In 2020, the

Computer History Museum The Computer History Museum (CHM) is a museum of computer history, located in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the information age, and explores the computing revolution and its impact o ...

worked with Ritchie's family and Fischer's family and found a copy of the lost dissertation. During the 1960s, Ritchie and

worked on the

Multics Multics ("Multiplexed Information and Computing Service") is an influential early time-sharing operating system based on the concept of a single-level memory.Dennis M. Ritchie, "The Evolution of the Unix Time-sharing System", Communications of ...

operating system at Bell Labs. Thompson then found an old

PDP-7 The PDP-7 was a minicomputer produced by Digital Equipment Corporation as part of the PDP series. Introduced in 1964, shipped since 1965, it was the first to use their Flip-Chip technology. With a cost of , it was cheap but powerful by the s ...

machine and developed his own application programs and operating system from scratch, aided by Ritchie and others. In 1970,

Brian Kernighan Brian Wilson Kernighan (; born 1942) is a Canadian computer scientist. He worked at Bell Labs and contributed to the development of Unix alongside Unix creators Ken Thompson and Dennis Ritchie. Kernighan's name became widely known through co- ...

suggested the name "

", 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 In cryptography, a ciphertext-only attack (COA) or known ciphertext attack is an attack model for cryptanalysis where the attacker is assumed to have access only to a set of ciphertexts. While the attacker has no channel providing access to the pla ...

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 National Security Agency (NSA) is a national-level intelligence agency of the United States Department of Defense, under the authority of the Director of National Intelligence (DNI). The NSA is responsible for global monitoring, collecti ...

, the authors decided not to publish it, as they were told that the principle was applicable to machines still in use by foreign governments. Ritchie was also involved with the development of the Plan 9 and Inferno operating systems, and the programming language

Limbo In Catholic theology, Limbo (Latin '' limbus'', edge or boundary, referring to the edge of Hell) is the afterlife condition of those who die in original sin without being assigned to the Hell of the Damned. Medieval theologians of Western Euro ...

. 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.

C and Unix

Ritchie is best known as the creator of the

, one of the developers of the

operating system, and co-author of the book ''

The C Programming Language ''The C Programming Language'' (sometimes termed ''K&R'', after its authors' initials) is a computer programming book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally designed and implemented the language, as well as ...

''; he was the 'R' in ''K&R'' (a common reference to the book's authors Kernighan and Ritchie). Ritchie worked together with

, who is credited with writing the original version of Unix; one of Ritchie's most important contributions to Unix was its porting to different machines and platforms. They were so influential on

Research Unix The term "Research Unix" refers to early versions of the Unix operating system for DEC PDP-7, PDP-11, VAX and Interdata 7/32 and 8/32 computers, developed in the Bell Labs Computing Sciences Research Center (CSRC). History The term ''Resear ...

that Doug McIlroy later wrote, "The names of Ritchie and Thompson may safely be assumed to be attached to almost everything not otherwise attributed." Ritchie liked to emphasize that he was just one member of a group. He suggested that many of the improvements he introduced simply "looked like a good thing to do", and that anyone else in the same place at the same time might have done the same thing. Nowadays, the C language is widely used in application,

, and

embedded system An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded ...

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 particular hardware—making it easy to write programs on any machine that supports C. Moreover, C is a high level language with constructs mapping to the application's data structures. C influenced several other languages and derivatives as

C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...

Objective-C Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. Originally developed by Brad Cox and Tom Love in the early 1980s, it was selected by NeXT for its NeXT ...

used by Apple, C# used by Microsoft, and

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...

extensively used in corporate environment and also by Android. Ritchie and Thompson used C to write UNIX. Unix has been influential establishing computing concepts and principles that have been widely adopted. In an interview from 1999, Ritchie clarified that he saw

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...

and BSD operating systems as a continuation of the basis of the Unix operating system, and as derivatives of Unix: In the same interview, he stated that he viewed both Unix and Linux as "the continuation of ideas that were started by Ken and me and many others, many years ago."

Awards

In 1983, Ritchie and Thompson received the

"for their development of generic operating systems theory and specifically for the implementation of the UNIX operating system". Ritchie's Turing Award lecture was titled "Reflections on Software Research". In 1990, both Ritchie and Thompson received the

IEEE Richard W. Hamming Medal The IEEE Richard W. Hamming Medal is presented annually to up to three persons, for outstanding achievements in information sciences, information systems and information technology. The recipients receive a gold medal, together with a replica ...

from the

Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operation ...

(IEEE), "for the origination of the UNIX operating system and the C programming language". In 1997, both Ritchie and Thompson were made Fellows of the

, "for co-creation of the UNIX operating system, and for development of the C programming language." On April 21, 1999, Thompson and Ritchie jointly received the

of 1998 from President

Bill Clinton William Jefferson Clinton (né Blythe III; born August 19, 1946) is an American politician who served as the 42nd president of the United States from 1993 to 2001. He previously served as governor of Arkansas from 1979 to 1981 and again ...

for co-inventing the UNIX operating system and the C programming language which, according to the citation for the medal, "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". In 2005, the

Industrial Research Institute Innovation Research Interchange (IRI) is a division of the National Association of Manufacturers, a nonprofit association based in Washington, D. C., United States. IRI was founded as a private non-profit in 1938 and merged with the NAM in 2022. I ...

awarded Ritchie its Achievement Award in recognition of his contribution to science and technology, and to society generally, with his development of the Unix operating system. In 2011, Ritchie, along with Thompson, was awarded the Japan Prize for Information and Communications for his work in the development of the Unix operating system.

Death

Dennis Ritchie (right) Receiving Japan Prize

Ritchie was found dead on October 12, 2011, at the age of 70 at his home in

Berkeley Heights, New Jersey Berkeley Heights is a township in Union County, New Jersey, United States. A commuter town in northern-central New Jersey, the township is nestled within the Raritan Valley region in the New York metropolitan area. As of the 2010 United State ...

, where he lived alone. First news of his death came from his former colleague,

Rob Pike Robert "Rob" Pike (born 1956) is a Canadian programmer and author. He is best known for his work on the Go (programming language), Go programming language and at Bell Labs, where he was a member of the Unix team and was involved in the creation o ...

. He had been in frail health for several years following treatment for

prostate cancer Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that su ...

and

heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, h ...

. News of Ritchie's death was largely overshadowed by the media coverage of the death of

Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ancest ...

co-founder

Steve Jobs Steven Paul Jobs (February 24, 1955 – October 5, 2011) was an American entrepreneur, industrial designer, media proprietor, and investor. He was the co-founder, chairman, and CEO of Apple; the chairman and majority shareholder of Pixar; ...

, which occurred the week before.

Legacy

Following Ritchie's death, computer historian

Paul E. Ceruzzi Paul E. Ceruzzi (born 1949) is curator emeritus at the Smithsonian's National Air and Space Museum in Washington, D.C. Life Ceruzzi received a BA from Yale University in 1970 and received a Ph.D. from the University of Kansas in 1981, both i ...

stated: In an interview shortly after Ritchie's death, long time colleague

said Ritchie never expected C to be so significant. Kernighan told ''

The New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...

'' "The tools that Dennis built—and their direct descendants—run pretty much everything today." Kernighan reminded readers of how important a role C and Unix had played in the development of later high-profile projects, such as the iPhone. Other testimonials to his influence followed. Reflecting upon his death, a commentator compared the relative importance of

and Ritchie, concluding that " itchie'swork played a key role in spawning the technological revolution of the last forty years—including technology on which Apple went on to build its fortune." Another commentator said, "Ritchie, on the other hand, invented and co-invented two key software technologies which make up the DNA of effectively every single computer software product we use directly or even indirectly in the modern age. It sounds like a wild claim, but it really is true." Another said, "many in computer science and related fields knew of Ritchie’s importance to the growth and development of, well, everything to do with computing,..." The Fedora 16

Linux distribution A Linux distribution (often abbreviated as distro) is an operating system made from a software collection that includes the Linux kernel and, often, a package management system. Linux users usually obtain their operating system by downloading one ...

, which was released about a month after he died, was dedicated to his memory.

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...

9.0, released January 12, 2012, was also dedicated in his memory. Asteroid

294727 Dennisritchie Year 947 ( CMXLVII) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. Events By place Europe * Summer – A Hungarian army led by Grand Prince Taksony campaigns in Italy, heading ...

, discovered by astronomers Tom Glinos and

David H. Levy David Howard Levy (born May 22, 1948) is a Canadian amateur astronomer, science writer and discoverer of comets and minor planets, who co-discovered Comet Shoemaker–Levy 9 in 1993, which collided with the planet Jupiter in 1994. Biography ...

in 2008, was named in his memory. The official was published by the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function T ...

on 7 February 2012 ().

Gallery

File:Dennis Ritchie in a chalet in the mountains surrounding Salt Lake City, Utah--Summer 1984, Usenix conference.jpg, Ritchie engaged in conversation in a

chalet A chalet (pronounced in British English; in American English usually ), also called Swiss chalet, is a type of building or house, typical of the Alpine region in Europe. It is made of wood, with a heavy, gently sloping roof and wide, well-suppo ...

in the mountains surrounding

Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the capital and most populous city of Utah, United States. It is the seat of Salt Lake County, the most populous county in Utah. With a population of 200,133 in 2020, th ...

at the 1984 Usenix conference. File:Usenix84 1.jpg, At the same Usenix 1984 conference, Dennis Ritchie is visible in the middle, wearing a striped sweater, behind Steven Bellovin wearing a baseball cap.

Notable works

* B programming language *

on which many currently used languages and technologies are based. *

, a multiuser operating system. Several workalikes (commonly referred to as

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...

systems) have been developed based on Unix's design. Some of these follow

POSIX The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming in ...

standards, again based on Unix. * '' Unix Programmer's Manual'' (1971) * ''

'' (sometimes referred to as ''K&R''; 1978 with

)

Publications and academic papers

Ritchie has been the author or contributor to about 50 academic papers, books and textbooks and which have had over 15,000 citations. Here are some of his most cited works: * The C programming language, BW Kernighan, DM Ritchie, Prentice Hall, Englewood Cliffs, New Jersey (1978) * Programming languages, D Ritchie (1978) *The UNIX time-sharing system, DM Ritchie, K Thompson, Classic operating systems, 195-220 (2001) *Advanced programming in the UNIX environment, WR Stevens, SA Rago, DM Ritchie, Addison-Wesley (1992, 2008)

References

External links

Dennis Ritchie's home page at Bell Labs

* * ttps://abcnews.go.com/Technology/video/unix-starting-point-personal-computer-13869282?tab=9482931§ion=1206840&playlist=11496627&page=1 Dennis Ritchie's video interview June 2011* * {{DEFAULTSORT:Ritchie, Dennis 1941 births 2011 deaths American computer scientists American technology writers Harvard School of Engineering and Applied Sciences alumni Turing Award laureates Multics people Unix people Plan 9 people Inferno (operating system) people C (programming language) Scientists at Bell Labs National Medal of Technology recipients Programming language designers People from Bronxville, New York People from Berkeley Heights, New Jersey People from Summit, New Jersey Summit High School (New Jersey) alumni 20th-century American inventors Scientists from New York (state)