CHAPTER 6

Turing’s great invention: the

universal computing machine

jack copeland

T

here is no such person as the inventor of the computer: it was a group effort. The

many pioneers involved worked in different places and at different times, some in

relative isolation and others within collaborative research networks. There are some

very famous names among them, such as Charles Babbage and John von Neumann—and,

of course, Alan Turing himself. Other leading names in this roll of honour include Konrad

Zuse, Tommy Flowers, Howard Aiken, John Atanasoff, John Mauchly, Presper Eckert, Jay

Forrester, Harry Huskey, Julian Bigelow, Samuel Alexander, Ralph Slutz, Trevor Pearcey,

Maurice Wilkes, Max Newman, Freddie Williams, and Tom Kilburn. Turing’s own outstand-

ing contribution was to invent what he called the ‘universal computing machine’. He was

first to describe the basic logical principles of the modern computer, writing these down in

1936, 12 years before the appearance of the earliest implementation of his ideas. This came in

1948, when Williams and Kilburn succeeded in wiring together the first electronic universal

computing machine—the first modern electronic computer.

A universal machine

In 1936, at the age of just 23, Turing invented the fundamental logical principles of the modern

computer—almost by accident. A shy boyish-looking genius, he had recently been elected a

Fellow of King’s College, Cambridge. The young Turing worked alone, in a spartan room at

the top of an ancient stone building beside the River Cam. It was all quite the opposite of a

modern research facility—Cambridge’s scholars had been doing their thinking in comfortless

stone buildings, reminiscent of cathedrals or monasteries, ever since the university had begun

to thrive in the Middle Ages.

A few steps from King’s, along narrow medieval lanes, are the buildings and courtyards

where, in the seventeenth century, Isaac Newton revolutionized our understanding of the uni-

verse. Turing was about to usher in another revolution. He was engaged in theoretical work in