Dennis Ritchie

Dennis Ritchie, who has died aged 70, was the co-creator of the Unix operating system, the software tool which powers the internet, and the equally important computer programming language known as “C”.

Dennis Ritchie 

For those with only a sketchy knowledge of computer-speak, the job of an operating system is to organise the various parts of the computer – the processor, the memory, the disk drives, keyboards, video monitors and so on – to perform useful tasks. A programming language, meanwhile, is usually an artificial shorthand of words, numbers and punctuation used to construct computer programs – including operating systems themselves.

Such is its utility in the modern world of computing that Unix has been described as “the best screwdriver ever built”. The operating system powers many of the world’s data centres, such as those at Google and Amazon, and its technology serves as the foundation of many different operating systems.

Steve Jobs used Unix as the basis for his NeXT computer workstation, and later it became the foundation for Apple’s smartphones and other products. In addition, computer languages such as C++ and Java were built on the C language that Ritchie devised. Meanwhile, the Unix philosophy of free access inspired the open source software movement and its Unix variant, Linux, which now powers most of the servers on which the internet depends.

Work on Unix began at AT&T’s Bell Laboratories in the late 1960s at a time when computers were generally huge, complex to use and typically overseen by men in white coats who jealously guarded access to them. The idea behind Unix was to design an easily portable system that could be run on the cheaper and smaller “minicomputers” that were in the early stages of development at the time. Ritchie explained that their aim was to produce “a system around which fellowship can form”.

Ritchie and his colleague Ken Thompson, the two researchers assigned to the project, set to work on the core components of the new operating system (known as shell, editor and assembler) and persuaded the Bell Labs patent department to acquire a full-sized DEC computer, known as the PDP7, and run Unix on it.

The first version of Unix had been written in a primitive programming language known as machine code , but it proved cumbersome and slow. So Ritchie invented a new language called C . By the early 1970s five people were working on Unix, and it soon had a long list of commands it could carry out, written in C.
Helped by AT&T’s decision to give the software away free, word about Unix soon spread among the academics who were the principal users of computers. Universities began to train their students in Unix and C, and when they graduated they took this training into industry. In May 1975 Unix was chosen as the operating system for the new computer network that grew into the internet, and it was subsequently adapted for use on many different computers. In the 1990s the rise of the web beyond halls of academia gave it a new lease of life.
In 1978 Ritchie and a colleague, Brian Kernighan, published The C Programming Language, widely known as “K&R”, which became a bestselling programming textbook, running into two editions and selling millions of copies in 25 languages.
Dennis MacAlistair Ritchie was born on September 9 1941 in Bronxville, New York state. His father was an engineer at Bell Labs. When Dennis was a child, the family moved to Summit, New Jersey, where he attended high school. He then went to Harvard, where he read Applied Mathematics.
Ritchie stayed on at Harvard to do graduate work, but while working at the computer centre at the Massachusetts Institute of Technology he decided he was more interested in computing than mathematics. He was recruited by the Sandia National Laboratories, which conducted atomic weapons research and testing, then in 1967 was recruited by Bell Labs to work on a new operating system known as Multics. When Bell pulled out of the project in 1969 after four years of development on the grounds that it was proving too complicated and costly, Ritchie and Ken Thompson began rethinking software philosophy and came up with Unix – “a kind of treacherous pun on Multics”, as Ritchie once explained.
Ritchie travelled widely and was well read, but his main passion was work, and he remained at Bell Labs until he retired in 2007.
In 1983 he and Thompson received the Turing award of the Association of Computing Machinery, the “Nobel Prize of computing”, and in 1998 were awarded the National Medal of Science by President Clinton. In 1999 Ritchie was awarded the US National Medal of Technology.
He was unmarried.