In the beginning ...
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 attributestegrated 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.