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Annals H~.st Comput (1989) 10 257-275
G American Federation of Information Processing Socletles
Electronics Technology and
Computer Science,
1940-l 975: A Coevolution
PAUL CERUZZI
This paper explores the relationship between two disciplines: electrical
engineering and computer science, over the past 40 years. The aufhor
argues that it was the technology of electronics-the exploitation of the
properfies of free electrons--that final/y permitted BabbageS concepts of
automatic computing machines to be practically realized. Electrical
Engineering (EE) activities thus “took over” and dominated
the
work of
those involved with computing. Once fhaf had been done (around the mid-
195Os), the reverse takeover happened: the soence of computing then
“took over” the discipline of Electrical Engineering, in
the
sense that its
theory of digital switches and separation of hardware and
software
offered
EE a guide
to
designing and building ever more complex
arcuits.
Categories and Subject Descriptors: K. 2.
[Computing Milieux]:
History
of Computing-hardware, software, systems, theory. A. 1,
[General
Literature]:
Introductions and Survey.
General Terms: Des/gn, Reliability, Theory.
Additional Terms: Computer
Science.
Electrical Engineering.
Introduction
In 1976, a colorful brochure put out by the IBM
Corporation had a startling title: “It Was to Have
Been the Nuclear Age. It Became The Computer
Age: the Evolution of IBM Computers” (Figure
11.’ Leaving aside the question whether it is proper
to identify any period of time by a piece of tech-
nology, the title does call attention to the fact that
the computer seems to have sprung up suddenly
and unexpectedly. to dominate much of the na-
tion’s technology, economy, and culture.
cades, and not sooner? A complete answer to this
question would include a mix of economic and so-
cial as well as technical factors. This essay fo-
cuses on an aspect of the internal development
of computer technology that was as important as
any: namely that after 1940, Babbage’s concep-
tual formulation of an computer was joined to an-
other technology that was well suited to its re-
alization. That technology was electronics.
Annals of the Hlstory of Computing, Volume 10, Number 4, 1989 . 257
But a sophisticated description of a digital
computer appeared in the writings of Charles
Babbage in the 1830s. Why, then, the appear-
ance
of a “computer age” in the past three de-
‘An earlier version of the paper was presented to the an-
nual meeting of the Society for History of Technology (SHOTi,
October 23, 1986. Pittsburgh, Pennsylvania.
Author’s Address:
Dept. of Space Science and Exploration,
National Air and Space Museum. Smithsonian Institution,
Washington, D.C. 20560. (202) 357-2828.
Electronics emerged as the “technology of
choice” for implementing the concept of a com-
puting machine between 1940 and 1955. As it did
so, it enabled persons not trained in Electrical
Engineering to exploit the power and versatility
of computers. This activity led to the sbudy of
“computing” independently of the technology out
of which “computers” were built. In other words,
it led to the creation of a new science: “Computer
Science.”
The term “coevolution” implies that there was
a continuous and reciprocal interaction between
electronics and computing. Such interaction did,
P. Ceruzzi
l
Coevolution of Electronics and Computer Science
in fact occur. As computer science matured, it re-
first automatic calculators, finally, after years of
hope and promise, came into existence. But al-
most from the start they were eclipsed by ma-
chines using the much faster vacuum tube as its
computing element. The story of the invention of
the electronic digital computer has been told
elsewhere, and in that story the issue of the vac-
uum tube’s perceived unreliability, as well as its
heavy power demands, are among the difficulties
cited for the initial skepticism as to its practi-
cality. These were indeed serious issues, but they
were addressed. Once they were, vacuum tube
technology, with its higher operating speeds, was
perceived as an alternative to relays.
paid its debt to electronics by offering that en-
gineering discipline a body of theory which served
to unify it above the level of the physics of the
devices themselves. In short, computer science
provided electrical engineering a paradigm, which
I call the “digital approach,” which came to de-
fine the daily activities of electrical engineers in
circuits and systems design.2
Though continuous, the interaction between
Computer Science and Electrical Engineering was
marked by two distinct phases. In the first phase,
between 1940-1955, electronics took over the
practice of computing. In the second, from 1955
to 1975, computing took over electronics. I shall
look at each in turn.
Between 1940 and 1950, a scattered group of
persons, without knowledge of one another, put
Babbage’s ideas into working machinery. These
inventors were interested in building machines
that could carry out a sequence of elementary
arithmetic operations, store intermediate results,
and recall those results automatically as needed,
and display or print the final results of the cal-
culation. They were not, for the most part, con-
cerned with the engineering details of their im-
plementation, except insofar as they wished to
have a machine that worked reliably (Cohen
19851. As things turned out, the first reliable,
working computers-in other words, the first
machines to implement Babbage’s idea of an au-
tomat.ic computing machine-used relays or sim-
ilar electromechanical elements to carry and ma-
nipulate numbers. Using relays (a technology
borrowed from the telephone industry), George
Stibitz of Bell Laboratories and Konrad Zuse of
the Henschel Aircraft Company in Berlin each
built calculators that could carry out three to five
arithmetic operations a second. And using a com-
bination of relays and toothed wheels borrowed
from punched-card accounting machines, How-
ard Aiken at Harvard built a powerful “Auto-
matic Sequence Controlled Calculator” with a
similar operating speed (Ceruzzi 1981).
Relay computers played the vital role of intro-
ducing the concept of automatic, sequential cal-
culation to an often skeptical community. It was
with electromechanical relay technology that the
Throughout this paper I ~111 be concentrating on that
branch of Electrical Engmeenng that IS more accurately de-
scribed as “electronic” engineering This term ~111 be defined
later in the text, but essentially I will not address that branch
of EE that deals with Power Engineering or the so-called
“Heavy Currents.”
One reason for the rapid ascendancy of elec-
tronic devices for computing elements was that
events during the war, mainly unrelated to
building computers, had transformed electronics
itself, raising it above the level considered (and
rejected) by the computer pioneers like Aiken or
Stibitz. One development-radar-was critical,
and became the bridge across which electronics
entered the realm of computing.
The role of radar is not usually considered as
Paul Ceruzzi was born
in Bridgeport,
Connecticut, and
attended Yale University,
where he received a
B.A. in 1970. He
attended graduate
school at the University
of Kansas, from which
he received his Ph.D. in
American Studies in
1981. His graduate
studies included a year as a Fulbright Scholar at
the Institute for the Hisfory of Science in
Hamburg, West Germany, and he received a
Charles Babbage Institute Research Fellowship in
1979. Before joining the staff of the National Air
and Space Museum, he taught History of
Technology at Clemson University in Clemson,
South Carolina.
Dr. Ceruzzi’s main scholarly work has been in
the history of computing since 1935. His has
written a book on this subject (Reckoners, the
Prehistory of The Digital Computer, 1935-
1945, Greenwood Press, 19831, and he is
presently working on a major new gallery at the
National Air and Space Museum about the
computer’s impact on air and space flight.
258
l
Annals of the History of Computing, Volume 10, Number 4, 1989
P. Ceruzzi
l
Coevolution of Electronics and Computer Science
IT V&S TO
i
t-!AVE BEEN THE
NUCLEAR AGE.
IT BECAME...
I
Figure 1. Brochure from IBM, undated, about 1976
(IBM Corporation).
part of the generational lineage of computer his-
tory, in contrast to, say, the invention and mar-
keting of mechanical adding machines. Yet among
those involved in modern computing’s first de-
cade, there was no question as to its influence.
Radar required vacuum tube circuits that han-
dled discrete pulses of current at high frequen-
cies, in contrast to radio transmitters and receiv-
ers which had been the mainstay of prewar
electronics engineering. Both these requirements
matched the needs of computer engineering. Ra-
dar sets typically contained over a hundred tubes,
again in contrast to the more modest four- or five-
t.ube radio sets of the day.
One link from radar to the computer was the
mercury delay line: an ingenious and tricky de-
vice developed with some difficulty for storing
radar pulses. After the war those who had ex-
perience with it ie.g. Maurice Wilkes at Cam-
bridge University in England and Presper Eckert
in Philadelphia) could adapt it for use as a com-
puter memory device. Those who were less fa-
miliar with it had less success, many (e.g. Aiken)
believing that such a device was so fragile that
it would never work in a computer (Wilkes 1985,
p. 128). Mercury delay lines were indeed difficult
to build and operate; nevertheless they played the
role of being the memory device for four of the
first five stored program computers to be built in
the United States and England:
EDSAC, BINAC,
SEAC,
and Pilot
ACE
(the exception was the
Manchester computer, later called “Mark I,” which
used a Williams-tube memory.3
In 1953, when the
IRE Proceedings
issued a
special “Computer Issue,” Werner Buchholz, the
guest editor, stated that although many com-
puter projects were started during WW II,
. .
Still, the present growth of the computer in-
dustry did not start until the results of the enor-
mous development of electronic technology dur-
ing World War II were brought into the field. It
is interesting to note that many computer proj-
ects started around a nucleus of wartime radar
experts. Electronics not only provided the tech-
nological means for greatly increased speed and
capacity, and thereby enhanced the usefulness of
computers many times, but the availability of
cheap, mass-produced components and of engi-
neers trained to use them made it possible to ex-
periment on a greater scale and at a lower cap-
ital investment than before (IRE 1953, p. 12201.
As a result of that development of electronics
technology between 1939 and 1945, employment
in the American electronics industries had risen
from 110,000
to 560,000 (Electronics
1980, pp. 150-
210).
The vacuum tube ascendancy was not imme-
diate, however. Experience with radar had at-
tacked many of the problems of reliability, but
these problems still remained. Just as serious was
the fact that the much faster operating speeds of
tubes required a rethinking of the overall struc-
ture of a computing machine, especially the way
it received its instructions. High electronic speeds
meant nothing if the computing circuits received
their orders by mechanical devices such as paper
tape or punched card readers. Likewise the high
arithmetic speeds had to be carefully matched to
equally high speeds for storing and retrieving in-
termediate results from memory devices. It was
also recognized that higher arithmetic speeds re-
quired greater memory capacities. Each of the first
electronic calculators (i.e., machines whose com-
puting program was not directed by a stored pro-
“See Table 1 for a full listing of these and other early com-
puters and their memory devices.
Annals of the History of Computing, Volume 10, Number 4, 1989
l
259