The Manchester Small-Scale Experimental Machine (SSEM), nicknamed Baby, was the world's first stored-program computer. It was built at the Victoria University of Manchester, England, by Frederic C. Williams, Tom Kilburn and Geoff Tootill, and ran its first program on 21 June 1948.The machine was not intended to be a practical computer but was instead designed as a testbed for the Williams tube, an early form of computer memory.