7 The 100 Most Influential Inventors of All Time 7and their colleagues at the Moore School of Electrical
Engineering at the University of Pennsylvania. Their
objective was an all-electronic computer, and work began
in early 1943 on the Electronic Numerical Integrator and
Computer (ENIAC). The next year, mathematician John
von Neumann—already on full-time leave from the
Institute for Advanced Studies in Princeton, N.J., for
various government research projects (including the
Manhattan Project)—began frequent consultations with
the group.
Completed by February 1946, ENIAC was something
less than the dream of a universal computer. Designed for
the specific purpose of computing values for artillery range
tables, it lacked some features that would have made it a
more generally useful machine. For instance, it used plug-
boards for communicating instructions to the machine.
This had the advantage that, once the instructions were
thus “programmed,” the machine ran at electronic speed.
The disadvantage was that it took days to rewire the
machine for each new problem. This was such a liability
that only with some generosity could ENIAC be called
programmable. Nevertheless, it was the most powerful
calculating device built to date and the first programmable
general-purpose electronic digital computer.
ENIAC was also enormous. It occupied the 50-by-30-
foot (15-by- 9 -metre) basement of the Moore School,
where its 40 panels were arranged, U-shaped, along three
walls. Each of the units was about 2 feet wide by 2 feet
deep by 8 feet high (0.6 metre by 0.6 metre by 2.4 metres).
With approximately 18,000 vacuum tubes, 70,000 resistors,
10,000 capacitors, 6,000 switches, and 1,500 relays, it was
easily the most complex electronic system ever built. A
portion of the machine is on exhibit at the Smithsonian
Institution in Washington, D.C.