In 1948, the SSEM (Small-Scale Experimental Machine), also known as the Manchester Baby or Baby, was introduced. Frederic Williams designed it, and with the assistance of Geoff Tootill, Tom Kilburn (his protégée) built it at the University of Manchester in England. The first electronically-stored program that was able to electronically store and execute a program written by Kilburn, which can calculate the highest proper factor of an integer with the help of repeated subtraction instead of division. On 21 June 1948, Kilburn’s program was executed.
In England, at the University of Cambridge Mathematical Laboratory, the EDSAC was designed and built by Maurice Wilkes, which was the second stored-program computer. It performed its first calculation on 6 May 1949. It was designed with an implementation of tic-tac-toe screened on a 6-inch cathode ray tube.
Another computer, Manchester Mark 1, was able to run stored programs. Also, at the Victoria University of Manchester, the first version of the Mark 1 computer was built in April 1949 that was able to run the program. Later, it was used to run a program for nine hours without error to search for Mersenne primes on 16 and 17 June.