Answer: SSEM

Although SSEM (Small-Scale Experimental Machine) contained all the components of a modern computer, it bore very little resemblance to the computers of today or even the computers that would follow it in the coming decades.

Produced by Manchester University computer engineers in 1948, SSEM was the world’s first stored-program computer. While many engineers going all the way back to Charles Babbage had designed program-controlled computers, the SSEM was the first computer to retain the program within itself and required no reprogramming to restore the functionality of the stored program. SSEM was built explicitly to test Williams Tubes, a type of cathode-ray tube memory that stored binary data electronically, and was never intended as a general purpose computer.

While the SSEM was never commercialized, the advances made in computer architecture through the project heavily influenced the design of the Manchester Mark 1, which was in turn revised and sold as the first commercial general purpose computer under the name Ferranti Mark 1 in 1951.