Backus was born in Philadelphia, the son of a stockbroker. As a teenager, he did not distinguish himself at school. He enrolled at the University of Virginia to study chemistry, as his father had done, but dropped out after six months. During his war service in the army, he briefly considered a career in medicine, but became disillusioned by the rote learning. At the end of the war, he discovered an aptitude for mathematics while training at a school for radio technicians, and went on to study the subject to postgraduate level at Columbia University, New York City.
Shortly before receiving his master's degree in 1949, Backus visited IBM's New York headquarters, where the company's latest computer was on public display. This machine, with its banks of flashing lights and whirring tapes, became the popular image of what a computer should look like. Backus mentioned that he was looking for a job and was invited to meet one of the machine's inventors, who asked him a series of technical questions and hired him on the spot. Backus spent the next two years programming the computer to perform scientific calculations, including precise predictions of the orbital position of the Moon that would later be used to plan the Apollo landings.
In 1954, IBM introduced the Model 704 Electronic Data-Processing Machine, the world's first mass-produced computer. Backus had worked on the design of the machine, but he was frustrated at the difficulties inherent in programming it. The machine only understood sequences of numerical codes, so programming was slow.
Backus decided that there had to be an easier way. It should be possible, he reasoned, to write the instructions for the computer in something resembling plain English, and have the computer translate that into the proper sequence of codes. He put this idea to his manager, who had the foresight to allow him to put together a small team to try it out. The result, announced in late 1956, was a "formula translation" language named Fortran, which enabled complex calculations to be expressed as a combination of English commands and mathematical formulae. Backus and his team confounded sceptics by demonstrating that programs written in Fortran were as efficient as those written in numerical codes. This was an important factor in ensuring the adoption of Fortran by the scientists and engineers who used the IBM 704.
Its success led to the creation of many other programming languages in the following years. With the Danish computer scientist Peter Naur, Backus developed a notation for describing the structure of computer languages, known as the Backus-Naur Form, which is still in use.
Backus joined IBM's research centre in Yorktown Heights in 1959, and moved to the company's San Jose, California, research laboratory in 1963. In the same year, he was made an IBM fellow, an accolade that was the personal gift of the chairman of the company in recognition of outstanding technical achievement. He remained with IBM for more than 40 years until his retirement in 1991. He received the 1977 Turing Award of the Association of Computing Machinery and the 1993 Charles Stark Draper Prize of the National Academy of Engineering. The National Science Foundation honoured him in 1975 with the award of its national medal.
All three awards cited his lasting contributions to computer science, which made the power of computers available to countless scientists and engineers.
Backus was married twice. His first marriage, to Marjorie Jamison, ended in divorce. His second wife, Barbara Stannard, died in 2004. He is survived by two daughters and a brother.
John Warner Backus, computer scientist, born December 3 1924; March 17 2007
Published: Thursday April 5, 2007 © The Guardian
The following correction was printed in the Guardian's Corrections and clarifications column, Wednesday April 11 2007
In the article above, the "whirring tapes" of IBM's latest computer in 1949 were an anachronism. Magnetic tape was first used to record computer data in 1951.