CHAPTER 20

Baby

jack copeland

T

he modern computer age began on 21 June 1948, when the first electronic universal

stored-program computer successfully ran its first program. Built in Manchester,

this ancestral computer was the world’s first universal Turing machine in hardware.

Fittingly, it was called simply ‘Baby’. The story of Turing’s involvement with Baby and with its

successors at Manchester is a tangled one.^1

The modern computer is born

The world’s first electronic stored-program digital computer ran its first program in the sum-

mer of 1948 (Fig. 20.1). ‘A small electronic digital computing machine has been operating suc-

cessfully for some weeks in the Royal Society Computing Machine Laboratory’, wrote Baby’s

designers, Freddie Williams and Tom Kilburn, in the letter to the scientific periodical Nature

that announced their success to the world.^2 Williams, a native of the Manchester area, had spent

his war years working on radar in rural Worcestershire. Kilburn, his assistant, was a blunt-

speaking Yorkshireman. By the end of the fighting there wasn’t much that, between them, they

didn’t know about the state of the art in electronics. In December 1945 the two friends returned

to the north of England to pioneer the modern computer.^3

Baby was a classic case of a small-scale university pilot project that led to successful commer-

cial development by an external company. The Manchester engineering firm Ferranti built its

Ferranti Mark I computer to Williams’s and Kilburn’s design: this was the earliest commercially

available electronic digital computer. The first Ferranti rolled out of the factory in February

1951.^4 UNIVAC I, the earliest computer to go on the market in the United States, came a close
second: the first one was delivered a few weeks later, in March 1951.^5
Williams and Kilburn developed a high-speed memory for Baby that went on to become a
mainstay of computing worldwide. It consisted of cathode-ray tubes resembling small television
tubes. Data (zeros and ones) were stored as a scatter of dots on each tube’s screen: a small focused
dot represented ‘1’ and a larger blurry dot represented ‘0’. The Williams tube memory, as the
invention was soon called, was also used in Baby’s immediate successors, built at Manchester