computer. In 1973, however, a federal
judge recognized Atanassoff’s work and
voided Sperry Rand’s patent on the
ENIAC, saying it had been derived from
Atanassoff’s invention. Today, Atanassoff
and Berry get the credit.
The Harvard Mark 1,or the Automat-
ic Sequence Controlled Calculator, was
built between 1939 and 1944 by American
computer scientist Howard H. Aiken
(1900–1973) and his team. It is thought of
as the first large-scale automatic digital
computer. But there are disagreements
about this, with some historians believing
that German engineer Konrad Zuse’s Z3
(see above) was the first such machine.
Other early computers were the
ENIAC 1and the UNIVAC. The ENIAC
(Electronic Numerical Integrator And
Calculator) was completed in 1946 at the
University of Pennsylvania; it used thou-
sands of vacuum tubes. Until 1973, it was thought of as the first semi-electronic digi-
tal computer. That credit was subsequently given to Atanassoff and Berry (see above).
The UNIVAC (UNIVersal Automatic Computer) was built in 1951 and was the first
computer to handle both numeric and alphabetic data. It also was the first commer-
cially available computer.
The third-generation integrated-circuit machines were used primarily during the
mid-1960s and 1970s, making the computers smaller, faster (close to a million opera-
tions per second), and far more reliable. The first commercial microprocessor was the
Intel 4004, which appeared in 1971. It could only add and subtract, and it was used to
power one of the first portable electronic calculators. The real push in microproces-
sors came during the late 1970s to 1990s, allowing for increasingly smaller and more
powerful computers. For example, in 1974 the Intel 8080 processor had a clock speed
of 2 megahertz (MHz); by 2004 the Pentium 4 (“Prescott”) had a clock speed of 3.6
gigahertz (GHz). Computers that use microprocessors include the personal computer
and personal digital assistant (PDA). The computer industry has continued rapid
growth, mainly thanks to the increased performance of advanced microprocessors.
What is a microprocessor?
A microprocessor is a silicon chip that contains a CPU, or central processing unit, which
is normally located on the main circuit board in a computer. (In the world of personal 363
MATH IN COMPUTING
Vannevar Bush was an American scientist who
invented the differential analyzer, the first general-
purpose analog computer. Library of Congress.