210 | 20 BABy
the logical control—go far beyond anything to be found in the ‘First draft’. This minor borrow-
ing is probably what Turing was referring to when he told a newspaper reporter in 1946 that he
gave ‘credit for the donkey work on the A.C.E. to Americans’.^82
Yet the similarities between Turing’s design and the von Neumann proposals are relatively
minor compared with the striking differences. Moreover, the fact that von Neumann exerted
some influence on ‘Proposed electronic calculator’ should not be allowed to mask the extent to
which Turing’s universal machine of 1936 was itself a fundamental influence on von Neumann.
making history
By the start of summer 1948, the Manchester Baby was wired together and ready to try out.
Painstakingly, Kilburn and Williams entered the first program by hand, literally bit by bit, using
a panel of switches to plant each bit in memory. The program’s function was to find the highest
factor of a given number, a task that many people can carry out easily on the back of an enve-
lope. Eventually the program was stored successfully on the screen of a single Williams tube. It
was a mere seventeen instructions long.
Gingerly, the start switch was pressed. ‘Immediately the spots on the display tube entered
a mad dance’, Williams related.^83 This turned out to be a ‘dance of death’, he said, a hiding
to nowhere that was repeated again and again during the following week. ‘But one day’, he
recounted, ‘there, shining brightly in the expected place, was the expected answer’. It was
Monday 21 June 1948, the first day of the modern computer age—never before had electronic
hardware run a stored program. Williams said drily ‘We doubled our effort immediately by
taking on a second technician’.
At Manchester Turing finally had his hands on a stored-program computer. He was soon
using Manchester University’s Ferranti Mark I to model biological growth (as described in
Chapters 33–35). Others also began to explore the computer’s potential, creating a starburst
of ‘firsts’ in the Manchester laboratory. Christopher Strachey, soon to be one of computing’s
leading luminaries, got an artificial intelligence program up and running as early as 1952: it
played draughts (checkers), soliciting its human opponent’s next move with a peremptory ‘pip
pip’ sound.^84 If the human player delayed too long, the computer’s printer would chatter out
impatiently
YOU MUST PLAY AT ONCE OR RESIGN
or even
I REFUSE TO WASTE ANY MORE TIME. GO AND PLAY WITH A HUMAN BEING.
Strachey hijacked the computer’s monitor tube—normally used for showing the engineers how
things were ticking over in the inner workings—and set it up so as to display a virtual draughts-
board (Fig. 20.2, which is from Strachey’s notes). This was the first time that a computer screen
was used for interactive game playing.
Williams and Kilburn had used a Williams tube to store digital text several years earlier, in
the autumn of 1947—another historic moment—and used the term ‘picture elements’ (nowa-
days always shortened to ‘pixels’) to refer to the discrete blips making up the letters.^85 A photo-
graph of their historic experiment showed primitive pixels emblazoned across the face of the
tube to read ‘C.R.T. STORE’ (for ‘cathode-ray tube store’).^86 What’s more, Williams and Kilburn