The First Generation:
1946-1958 (The Vacuum Tube Years)
The first
generation computers were huge, slow, expensive, and often undependable. In
1946two
Americans, Presper Eckert, and John Mauchly built the ENIAC
electronic computer which used vacuum tubes instead of the mechanical switches
of the Mark I. The ENIAC used thousands of vacuum tubes, which took up a
lot of space and gave off a great deal of heat just like light bulbs do. The
ENIAC led to other vacuum tube type computers like the EDVAC (Electronic
Discrete Variable Automatic Computer) and the UNIVAC I (UNIVersal
Automatic Computer).
The vacuum tube was an extremely important step in the advancement of
computers. Vacuum tubes were invented the same time the light bulb was
invented by Thomas Edison and worked very similar to light bulbs. It's purpose
was to act like an amplifier and a switch. Without
any moving parts, vacuum tubes could take very weak signals and make the signal
stronger (amplify it). Vacuum tubes could also stop and start the
flow of electricity instantly (switch). These two properties made
the ENIAC computer possible.
The ENIAC gave off so much heat that they had to be cooled by
gigantic air conditioners. However even with these huge coolers, vacuum tubes
still overheated regularly. It was time for something new.
The Second Generation:
1959-1964 (The Era of the Transistor)
The transistor computer did not last as long as the vacuum
tube computer lasted, but it was no less important in the advancement of
computer technology. In 1947 three scientists, John Bardeen, William Shockley,
and Walter Brattain working at AT&T's Bell Labs invented what
would replace the vacuum tube forever. This invention was the transistor
which functions like a vacuum tube in that it can be used to relay and switch
electronic signals.
There were obvious differences between the
transisitor and the vacuum tube. The transistor was faster, more reliable,
smaller, and much cheaper to build than a vacuum tube. One transistor replaced
the equivalent of 40 vacuum tubes. These transistors were made of solid
material, some of which is silicon, an abundant element (second only to
oxygen) found in beach sand and glass. Therefore they were very cheap to
produce. Transistors were found to conduct electricity faster and
better than vacuum tubes. They were also much smaller and gave
off virtually no heat compared to vacuum tubes. Their use marked a new
beginning for the computer. Without this invention, space travel in the 1960's
would not have been possible. However, a new invention would even
further advance our ability to use computers.
The Third Generation:
1965-1970 (Integrated Circuits - Miniaturizing the Computer)
Transistors were a tremendous breakthrough in
advancing the computer. However no one could predict that thousands even now
millions of transistors (circuits) could be compacted in such a small space.
The integrated circuit, or as it is sometimes referred to as
semiconductor chip, packs a huge number of transistors onto a single
wafer of silicon. Robert Noyce of Fairchild
Corporation and Jack Kilby of Texas Instruments independently
discovered the amazing attributes of integrated circuits. Placing such large
numbers of transistors on a single chip vastly increased the power of a single
computer and lowered its cost considerably.
Since the invention of integrated circuits, the
number of transistors that can be placed on a single chip has doubled
every two years, shrinking both the size and cost of computers even
further and further enhancing its power. Most electronic devices today use some
form of integrated circuits placed on printed circuit boards-- thin
pieces of bakelite or fiberglass that have electrical connections
etched onto them -- sometimes called a mother board.
These third generation computers could carry out
instructions in billionths of a second. The size of these machines dropped to
the size of small file cabinets. Yet, the single biggest advancement in
the computer era was yet to be discovered.
The Fourth Generation:
1971-Today (The Microprocessor)
This generation can be characterized by both the jump to
monolithic integrated circuits(millions of transistors put onto one
integrated circuit chip) and the invention of the microprocessor (a
single chip that could do all the processing of a full-scale computer).
By putting millions of transistors onto one single chip more calculation
and faster speeds could be reached by computers. Because electricity travels
about a foot in a billionth of a second, the smaller the distance the greater
the speed of computers.
However what really triggered the tremendous growth of computers and
its significant impact on our lives is the invention of the
microprocessor. Ted Hoff, employed by Intel (Robert
Noyce's new company) invented a chip the size of a pencil eraser that
could do all the computing and logic work of a computer. The microprocessor was
made to be used in calculators, not computers. It led, however, to the
invention of personal computers, or microcomputers.
It wasn't until the 1970's that people began buying computer for
personal use. One of the earliest personal computers was the Altair 8800 computer kit.
In 1975 you could purchase this kit and put it together to make your own
personal computer. In 1977 the Apple II was sold to the public and in 1981 IBM
entered the PC (personal computer) market
Fifth Generation (Present and Beyond) Artificial Intelligence
Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization
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