The Manchester baby reborn [Small Scale Experimental Machine]

A program was laboriously inserted and the start switch pressed. Immediately the spots on the display tube entered a mad dance. In early trials it was a dance of death leading to no useful result. But one day it stopped and there shining brightly in the expected place, was the expected answer. So Prof Sir Frederic Williams described how a stored program successfully ran on a computer for the first time in the world on 21 June 1948. That historic event was one of the major steps in ushering in the information age, the second industrial revolution. The countless millions of people who use a computer today would find the principle of that event, to load and run a program in a universal machine, exactly as they do every day. And no earlier computer, for example the huge ENIAC machine at the University of Pennsylvania, could claim that 'likeness'. The computer was the Small-Scale Experimental Machine (SSEM) at Manchester University, later enlarged to become the Manchester Mark 1. That computer was dismantled and the parts dispersed in 1951-52 to be replaced by an engineered version, the Ferranti Mark 1, the first commercially delivered computer in the world. Fifty years ago, the first successful running of a stored program marked the beginning of a new era in computing. The author describes how the machine responsible, Manchester University's "Baby", has been rebuilt to mark the anniversary.