After
the abacus, the next major advance in the automation of calculation
came from the invention of logarithms by John Napier in the early
years of the seventeenth century. The beauty of logarithms lies in
the fact that when two numbers are to be multiplied, the answer can
be obtained by adding their logarithms. This invention was soon embodied
into a physical device which allowed fast calculations, even though
accuracy was not great. This was the slide rule which was the
standard
method of calculation of scientist and engineers until the advent
of the hand-held calculator in the early 1970s.
Pascaline
Machine
In 1642, shortly after Napier's invention of the logarithm, the French
mathematician Blaise Pascal designed and built the "pascaline,"
a mechanical adding machine comprised of sets of interlocking cogs
and wheels. Although not a commercial success, it formed the model
on which Gottfried Leibnitz designed his calculating machine which
was more successful.
At about the same time, in 1666, Sir Samuel Morland improved Napier's
slide rule principle by using a series of disks. His adding machine,
it was claimed, could add, subtract, divide, and multiply with great
accuracy. Other people, too, designed and produced similar machines
with varying degrees of success. The best known of these was Charles
Babbage who, although never successful in producing a completed version
of one of his machines, was very influential in the design of later
ones.
Difference
Machine & Analytical Engine
The
first of Babbage's calculating machines was called the difference
machine. It was so name because it used a method of adding differences
between numbers to calculate. On the basis of a highly successful
prototype, the British government provided financial support to Babbage
to build a larger, more useful version. Unfortunately, this was never
completed, largely due to the inability to produce cogs to the accurracy
demanded by the machine. Despite setbacks in the difference machine,
Babbage was undaunted and designed the analytical
engine; it can be called the prototype of the computer
because not only could it perform the basic mathematical operations,
but it also had separate devices for entering information, overseeing
the calculation, sorting numbers, and providing output -- the four
basic features of a computer. Instructions were to be given to the
machine by means of cards with holes punched in them. Metal rods falling
through the holes would signal the operation required. This idea of
using punched cards had originated in an automated loom built at the
beginning of the nineteenth century by a Frenchman, Joseph Jacquard.
The
Hollerith Machine
The
next major advance came about as the result of a competition held
for the 1890 census in the United States. As a result of the competition,
a device built by Herman Hollerith was used to tally all the census
figures. The Hollerith machine employed a card system like that invented
by Jacquard, in which metal rods passed through holes closing an electrical
circuit. Every time the circuit was closed, a counter advanced. After
the success in the 1890 census, Hollerith founded the Tabulating Machine
Company, which later merged with other companies to become the International
Business Machines Corporation
(IBM).
The
Mark I & Mark II Machines
Just
before World War II, Thomas Watson, head of IBM, funded Howard Aiken,
a mathematics professor at Harvard, to construct an electro-mechanical
equivalent of Babbage's analytical machine. Unveiled in 1944 and costing
nearly one million dollars to build, Aiken's machine known as the
Mark I was born. Rather than using gears, the Mark I used electromagnetic
relays that would click open and closed. The sound it made was reminiscent
of a room full of people knitting. The Mark I was over 50 feet long
and 8 feet tall; it had one million parts and 500 miles of wire. Mark
I's sister computer, the Mark II, is the subject of a story now infamoulsy
associated with the malfunction of modern day computers. During one
of Mark II's occasional malfunctions, technicians discovered a moth
mortally caught in one of the relays. The hapless insect was removed
but remains infamous as the first computer "bug".
First
Remote Public Access Machine
George
Stibitz of Bell laboratories produced some small computers based on
sequences of relays as well. However, in a demonstration to members
of the American Mathematical Society in 1940, he transmitted problems
by telephone line from Hanover, New Hampshire, to New York City, where
they were solved and the answers were transmitted back to Hanover,
where they were automatically printed out. As far as it is known,
this was the first public demonstration of accessing a computer from
a remote site.
The
Colossus Machine
At
the same time both Germans and the British were developing primitive
computers, the advances made by Germany's Konrad Zuse went unnoticed
because his computers were destroyed in air raids, and after World
War II, no one thought he had much to offer. The British, on the other
hand, developed a computer, known as Colossus, which was
used to deciper supposedly secure German codes.
ENIAC:
the first modern computer
Credit
for producing the first computer, in contrast to a calculating machine,
is generally accorded to John Atanasoff, a physicist at Iowa State
University who, together with an assistant, Clifford Berry, produced
the ABC or Atanasoff-Berry-Computer. Based on Atanasoff's
ideas, John Mauchly and Presper Eckert of the University of Pennsylvania
produced one of the most influential computers -- the ENIAC
-- or Electronic Numerical Integrator and Calculator. The
motivation for its production was a Department of Defense need to
calculate quickly the trajectories of various types of missiles. The
ENIAC, which was eventually completed after World War II, was a massive
machine consisting of 18,000 vacuum tubes and 1,500 relays. It was
based on the decimal system and had to be rewired each time a new
function was to be performed. ENIAC performed in half a minute the
trajectory calculations that took the average person about 20 hours.
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