COPElAND | 201
Jack Good. Until recently, Turing’s influence on Kilburn’s early thinking about computer archi-
tecture went completely unrecognized. Turing showered Kilburn with original ideas, while
Good (although a brilliant and original thinker himself ) acted mainly as a go-between, sup-
plying Kilburn with design ideas that originated in the United States. Newman, too, exposed
Williams and Kilburn to American thinking.
As I shall explain, the logical design of the 1948 Baby was virtually identical to a 1946 design
produced by John von Neumann (Fig. 6.3) and his computer group at Princeton’s Institute
of Advanced Study. It was as electronic engineers, not as computer architects, that Williams
and Kilburn led the world in 1948. In effect Newman and Good acted as messengers between
the Princeton group and Kilburn and Williams, transferring information about the Princeton
design. Kilburn seems to have remained quite unaware of the true source of the logical ideas
he acquired from Newman and Good, while Williams acknowledged that his and Kilburn’s
thinking might (via Newman) have been indirectly influenced by von Neumann, although he
too seemed to have no inkling of the true extent of this influence.^8
The intellectual traffic was not all one way, however. In the summer of 1948, when the
Princeton project was hopelessly bogged down with memory problems, von Neumann’s chief
engineer, Julian Bigelow, visited Williams’s laboratory at Manchester.^9 Bigelow, who extolled
Williams’s ‘inventive genius’, realized that the Manchester tube memory was exactly what the
Princeton group needed. When their vast computer was finished in 1951—the first of the
so-called Princeton class computers—its main memory consisted of forty Williams tubes,
compared with just one in Baby. The Manchester tube memory made ‘a whole generation of
electronic computers possible’, said Herman Goldstine, one of the Princeton group’s leading
lights.^10 The Princeton computer’s commercial offspring, the IBM 701, was IBM’s first stored-
program electronic computer. Its unveiling, complete with the Williams tube memory, marked
the dawn of a new era in computer sales.
By a wonderful coincidence, Turing himself had outlined a design for a computer memory
closely resembling the Williams tube six months or more before Williams even entered the
field. In his report ‘Proposed electronic calculator’ (the document setting out the design of his
ACE), Turing wrote that ‘a suitable storage system can be developed without involving any new
types of tube, using in fact an ordinary cathode-ray tube with tin-foil over the screen to act as
a signal plate’. This was exactly the arrangement later adopted by Williams. Turing continued:^11
It will be necessary to furbish up the charge pattern from time to time, as it will tend to become
dissipated . . . If we were always scanning the pattern in a regular manner as in television this
would raise no serious problems. As it is we shall have to provide fairly elaborate switching
arrangements to be applied when we wish to take off a particular piece of information. It will be
necessary to . . . switch to the point from which the information required is to be taken, do some
scanning there, replace the information removed by the scanning, and return to refurbishing
from the point left off.
Turing was certainly correct that the key problem was how to ‘furbish up’ the stored
patterns—the zeros and ones—before they leaked away. The solution he proposed in this quota-
tion was essentially the method subsequently adopted by Williams: the way to stop the pattern
disappearing—in other words, the way to make the tube ‘remember’ the data written on its
screen—was to scan the face of the tube continually, reading and then rewriting each digit.
As Williams later explained it, ‘you go and look at a spot and say “what’s there?”, all right that’s
there, so you put it back’.^12