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The Manchester computers were an innovative series of stored-program electronic computers developed during the 30-year period between 1947 and 1977 by a small team at the University of Manchester, under the leadership of Tom Kilburn. They included the world's first stored-program computer, the world's first transistorised computer, and what was the world's fastest computer at the time of its inauguration in 1962.

The project began with two aims: to prove the practicality of the Williams tube, an early form of computer memory based on standard cathode ray tubes (CRTs); and to construct a machine that could be used to investigate how computers might be able to assist in the solution of mathematical problems. The first of the series, the Small-Scale Experimental Machine (SSEM), ran its first program on 21 June 1948. As the world's first stored-program computer, the SSEM, and the Manchester Mark 1 developed from it, quickly attracted the attention of the United Kingdom government, who contracted the electrical engineering firm of Ferranti to produce a commercial version. The resulting machine, the Ferranti Mark 1, was the world's first commercially available general-purpose computer.

The collaboration with Ferranti eventually led to an industrial partnership with the computer company ICL, who made use of many of the ideas developed at the university, particularly in the design of their 2900 series of computers during the 1970s.

The Manchester Small-Scale Experimental Machine (SSEM), also known as the Baby, was designed as a test-bed for the Williams tube, an early form of computer memory, rather than as a practical computer. Work on the machine began in 1947, and on 21 June 1948 the computer successfully ran its first program, consisting of 17 instructions written to find the highest proper factor of 2¹⁸ (262,144) by trying every integer from 2¹⁸ − 1 downwards. The program ran for 52 minutes before producing the correct answer of 131,072.

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