1-17. ELECTRONIC NUMERICAL INTEGRATOR AND COMPUTER.
a. Importance of the Electronic Numerical Integrator and Computer.
Between 1939 and 1946, engineers John P. Eckert and John W. Mauchley headed a
team of 50 at the Moore School to work on the Army's secret project. By 1945, they
built the Electronic Numerical Integrator and Computer (ENIAC), the first high-speed,
all-electronic computer. The Electronic Numerical Integrator and Computer could
effectively track the trajectory of rockets and missiles. However, with the war nearly
over, ENIAC was used to evaluate the feasibility of the hydrogen bomb and it continued
to be used in the cold war years (1946--1955) to test new systems.
b. The Cumbersome Decimal-Based the Electronic Numerical Integrator
and Computer. The Electronic Numerical Integrator and Computer was a terribly
complicated computer. Because it handled numbers in decimal form, it needed about
17,468 vacuum tubes. Mauchley preferred the familiar decimal approach because he
wanted "the equipment to be readable in human terms." However, this meant frequent
breakdowns. With so many tubes operating at a rate of 100,000 pulses per second,
there were 1.7 billion chances every second of a tube failing.
vacuum tube: electronic circuits used in first-generation computers,
eventually replaced by transistors and then by integrated circuits.
c. Key Drawback: Wire-Your-Own Programming. The Electronic Numerical
Integrator and Computer's main drawback was the difficulty in changing its instructions
or programs. Reprogramming involved an awkward process of rewiring. Someone who
wanted to switch from calculating artillery-firing tables to designing a bridge had to plug
and unplug hundreds of wires, and depending on the program's complexity, rewiring
could take anywhere from 4 hours to 2 days. This wire-your-own programming
drawback resulted from the fact that ENIAC had only enough internal memory to handle
the numbers involved in the computations it was performing. Programs had to be
literally wired into the complex circuitry. (EDVAC, Eckert and Mauchley's next project,
would feature a stored program, which was central to the concept of the modern
d. Size, Space, and Heat. By today's standards, ENIAC seems primitive,
occupying 2800 square feet and requiring over 17,000 vacuum tubes. Vacuum tubes
took up space, gobbled electricity, generated heat, and burned out rapidly. If one tube
went out, the whole system went down. The Electronic Numerical Integrator and
Computer 's 17,468 tubes gave off so much heat that, despite fans intended to cool the
machine, the temperature in the room sometimes reached 120F. Vacuum tubes, wrote
one historian, "afflicted the early computer with a kind of technological elephantiasis."