"Computer technology" and
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system (disambiguation)
A computer is a general purpose device that can
be programmed to carry out a finite set of arithmetic or logical operations.
Since a sequence of operations can be readily changed, the computer can solve
more than one kind of problem.
Conventionally, a computer consists of at least
one processing element, typically a central processing unit (CPU) and some form
of memory. The processing element carries out arithmetic and logic operations,
and a sequencing and control unit that can change the order of operations based
on stored information. Peripheral devices allow information to be retrieved
from an external source, and the result of operations saved and retrieved.
History of
computing
The first electronic digital computers were
developed between 1940 and 1945. Originally they were the size of a large room,
consuming as much power as several hundred modern personal computers (PCs). In
this era mechanical analog computers were used for military applications.
Modern computers based on integrated circuits are
millions to billions of times more capable than the early machines, and occupy
a fraction of the space. Simple computers are small enough to fit into mobile
devices, and mobile computers can be powered by small batteries. Personal
computers in their various forms are icons of the Information Age and are what
most people think of as “computers.” However, the embedded computers found in
many devices from MP3 players to fighter aircraft and from toys to industrial
robots are the most numerous.
The first use of the word “computer” was recorded in
1613 in a book called “The yong mans gleanings” by English writer Richard
Braithwait I haue read the truest computer of Times, and the best Arithmetician
that euer breathed, and he reduceth thy dayes into a short number. It referred
to a person who carried out calculations, or computations, and the word
continued with the same meaning until the middle of the 20th century. From the
end of the 19th century the word began to take on its more familiar meaning, a
machine that carries out computations.
Limited-function
early computers
The history of the modern computer begins with two
separate technologies, automated calculation and programmability. However no
single device can be identified as the earliest computer, partly because of the
inconsistent application of that term. A few devices are worth mentioning
though, like some mechanical aids to computing, which were very successful and
survived for centuries until the advent of the electronic calculator, like the
Sumerian abacus, designed around 2500 BC of which a descendant won a speed
competition against a modern desk calculating machine in Japan in 1946, the
slide rules, invented in the 1620s, which were carried on five Apollo space missions,
including to the moon and arguably the astrolabe and the Antikythera mechanism,
an ancient astronomical analog computer built by the Greeks around 80 BC. The
Greek mathematician Hero of Alexandria (c. 10–70 AD) built a mechanical theater
which performed a play lasting 10 minutes and was operated by a complex system
of ropes and drums that might be considered to be a means of deciding which
parts of the mechanism performed which actions and when. This is the essence of
programmability.
Blaise Pascal invented the mechanical calculator in
1642, known as Pascal's calculator, it was the first machine to better human
performance of arithmetical computations and would turn out to be the only
functional mechanical calculator in the 17th century. Two hundred years later,
in 1851, Thomas de Colmar released, after thirty years of development, his
simplified arithmometer; it became the first machine to be commercialized
because it was strong enough and reliable enough to be used daily in an office
environment. The mechanical calculator was at the root of the development of
computers in two separate ways. Initially, it was in trying to develop more
powerful and more flexible calculators that the computer was first theorized by
Charles Babbage and then developed. Secondly, development of a low-cost
electronic calculator, successor to the mechanical calculator, resulted in the
development by Intel of the first commercially available microprocessor
integrated circuit.
First general-purpose computers
In 1801, Joseph Marie Jacquard made an improvement to
the textile loom by introducing a series of punched paper cards as a template
which allowed his loom to weave intricate patterns automatically. The resulting
Jacquard loom was an important step in the development of computers because the
use of punched cards to define woven patterns can be viewed as an early, albeit
limited, form of programmability.
It was the fusion of automatic calculation with
programmability that produced the first recognizable computers. In 1837,
Charles Babbage was the first to conceptualize and design a fully programmable
mechanical computer, his analytical engine.[19] Limited finances and Babbage's
inability to resist tinkering with the design meant that the device was never
completed—nevertheless his son, Henry Babbage, completed a simplified version
of the analytical engine's computing unit (the mill) in 1888. He gave a
successful demonstration of its use in computing tables in 1906. This machine
was given to the Science museum in South Kensington in 1910.
Between 1842 and 1843, Ada Lovelace, an analyst of
Charles Babbage's analytical engine, translated an article by Italian military
engineer Luigi Menabrea on the engine, which she supplemented with an elaborate
set of notes of her own, simply called Notes. These notes contain what is
considered the first computer program – that is, an algorithm encoded for
processing by a machine. Lovelace's notes are important in the early history of
computers. She also developed a vision on the capability of computers to go
beyond mere calculating or number-crunching while others, including Babbage
himself, focused only on those capabilities.
In the late 1880s, Herman Hollerith invented the
recording of data on a machine-readable medium. Earlier uses of
machine-readable media had been for control, not data. “After some initial
trials with paper tape, he settled on punched cards...”[22] To process these
punched cards he invented the tabulator, and the keypunch machines. These three
inventions were the foundation of the modern information processing industry.
Large-scale automated data processing of punched cards was performed for the
1890 United States Census by Hollerith's company, which later became the core
of IBM. By the end of the 19th century a number of ideas and technologies, that
would later prove useful in the realization of practical computers, had begun
to appear: Boolean algebra, the vacuum tube (thermionic valve), punched cards
and tape, and the teleprinter.
During the first half of the 20th century, many
scientific computing needs were met by increasingly sophisticated analog
computers, which used a direct mechanical or electrical model of the problem as
a basis for computation. However, these were not programmable and generally
lacked the versatility and accuracy of modern digital computers.
Alan Turing is widely regarded as the father of modern
computer science. In 1936, Turing provided an influential formalization of the
concept of the algorithm and computation with the Turing machine, providing a
blueprint for the electronic digital computer.[23] Of his role in the creation
of the modern computer, Time magazine in naming Turing one of the 100 most
influential people of the 20th century, states: “The fact remains that everyone
who taps at a keyboard, opening a spreadsheet or a word-processing program, is
working on an incarnation of a Turing machine.
The Atanasoff–Berry Computer (ABC) was the world's
first electronic digital computer, albeit not programmable.[24] Atanasoff is
considered to be one of the fathers of the computer.[25] Conceived in 1937 by
Iowa State College physics professor John Atanasoff, and built with the
assistance of graduate student Clifford Berry,[26] the machine was not
programmable, being designed only to solve systems of linear equations. The
computer did employ parallel computation. A 1973 court ruling in a patent
dispute found that the patent for the 1946 ENIAC computer derived from the
Atanasoff–Berry Computer.
The first program-controlled computer was invented by
Konrad Zuse, who built the Z3, an electromechanical computing machine, in
1941.[27] The first programmable electronic computer was the Colossus, built in
1943 by Tommy Flowers.
George Stibitz is internationally recognized as a
father of the modern digital computer. While working at Bell Labs in November
1937, Stibitz invented and built a relay-based calculator he dubbed the “Model
K” (for “kitchen table,” on which he had assembled it), which was the first to
use binary circuits to perform an arithmetic operation. Later models added
greater sophistication including complex arithmetic and programmability.
Key steps towards modern computers
A succession of steadily more powerful and flexible
computing devices were constructed in the 1930s and 1940s, gradually adding the
key features that are seen in modern computers. The use of digital electronics
(largely invented by Claude Shannon in 1937) and more flexible programmability
were vitally important steps, but defining one point along this road as “the
first digital electronic computer” is difficult.Shannon 1940 Notable
achievements include:
Konrad Zuse's electromechanical “Z machines.” The Z3
(1941) was the first working machine featuring binary arithmetic, including
floating point arithmetic and a measure of programmability. In 1998 the Z3 was
proved to be Turing complete, therefore being the world's first operational
computer.[29] Thus, Zuse is often regarded as the inventor of the
computer.[30][31][32][33]
The non-programmable Atanasoff–Berry Computer
(commenced in 1937, completed in 1941) which used vacuum tube based
computation, binary numbers, and regenerative capacitor memory. The use of
regenerative memory allowed it to be much more compact than its peers (being
approximately the size of a large desk or workbench), since intermediate
results could be stored and then fed back into the same set of computation
elements.
The secret British Colossus computers (1943),[34]
which had limited programmability but demonstrated that a device using
thousands of tubes could be reasonably reliable and electronically re-programmable.
It was used for breaking German wartime codes.
The Harvard Mark I (1944), a large-scale
electromechanical computer with limited programmability.[35]
The U.S. Army's Ballistic Research Laboratory ENIAC
(1946), which used decimal arithmetic and is sometimes called the first general
purpose electronic computer (since Konrad Zuse's Z3 of 1941 used electromagnets
instead of electronics). Initially, however, ENIAC had an architecture which
required rewiring a plugboard to change its programming.
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