born Sept. 9, 1941 in Bronxville, N.Y., and received Bachelor's and advanced degrees from Harvard University, where as an undergraduate. He concentrated in Physics and as a graduate student in Applied Mathematics. The subject of his 1968 doctoral thesis was subrecursive hierarchies of functions.He joined Bell Labs in 1967, following his father, Alistair E. Ritchie, who had a long career there. His most visible public accomplishment was as co-author of The Design of Switching Circuits, with W. Keister and S. Washburn; it was an influential book on switching theory and logic design just before the transistor era
Early in the development of Unix, he added data types and new syntax to Thompson's B language, thus producing the new language C. C was the foundation for the portability of Unix, but it has become widely used in other contexts as well; much application and system development for computers of all sizes, from hand-held to supercomputer, uses it. There are unified U.S. and international standards for the language, and it is the basis for Stroustrup's work on its descendant C++.
Awards: ACM award for the outstanding paper of 1974 in systems and languages; IEEE Emmanuel Piore Award (1982), Bell Laboratories Fellow (1983); Association for Computing Machinery Turing Award (1983); ACM Software Systems Award (1983); C&C Foundation award of NEC (1989); IEEE Hamming Medal (1990). He was elected to the U. S. National Academy of Engineering in 1988. In April 1999 he received the U. S. National Medal of Technology. These were all awarded in conjunction with Ken Thompson.