Computer technology has become a vital part of business in the 20th century
The modern electronic digital computer is the result of a long series of developments, which started some 5000 years ago with the abacus. The first mechanical adding device was developed in 1642 by the French scientist-philosopher, Pascal. His 'arithmetic machine', was followed by the 'stepped reckoner' invented by Leibnitz in 1671, which was capable of also doing multiplication, division, and the evaluation of square roots by a series of stepped additions, not unlike the methods used in modern digital computers.

In 1835, Charles Babbage formulated his concept of an 'analytical machine' which combined arithmetic processes with decisions based on the results of the computations. This was really the forerunner of the modern digital computer, in that it combined the principles of sequential control, branching, looping, and storage units.

In the later 19th-c, George Boole developed the symbolic binary logic which led to Boolean algebra and the binary switching methodology used in modern computers. Herman Hollerith, a US statistician, developed punched card techniques, mainly to aid with the US census at the turn of the century; this advanced the concept of automatic processing, but major developments awaited the availability of suitable electronic devices. S Presper Eckert and John W Manchly produced the first all-electronic digital computer, ENIAC (Electronic Numerical Integrator and Calculator), at the University of Pennsylvania in 1946, which was 1000 times faster than the mechanical computers.A computer keyboard

Their development of ENIAC led to one of the first commercial computers,UNIVAC', in the early 1950s, which was able to handle both numerical and alphabetical information. Very significant contributions were made around this time by John von Neumann, who converted the ENIAC principles to give the EOVAC computer (Electronic Discrete Variable Automatic Computer) which could modify its own programs in much the same way as suggested by Babbage

The first stored program digital computer to run an actual program was built at Manchester University, UK and first performed successfully in 1948. This computer was later developed into the Ferranti Mark I computer, widely sold. The first digital computer (EOSAC) to be able to be offered as a service to users was developed at Cambridge University, UK, and ran in the spring of 1949. The EOSAC design was used as the basis of the first business computer system, the Lyons Electronic Office.

Advances followed rapidly from the 1950s, and were further accelerated from the mid- 1960s by the successful development of miniaturization techniques in the electronics industry. The first microprocessor, which might be regarded as a computer on a chip, appeared in 1971, and nowadays the power of even the most modest personal computer can equal or outstrip the early electronic computers of the 1940s.

An SCSI cable
Additional information provided by Cambridge Dictionary of Scientists

The Development of the Computer

Computers today are used to perform a dazzlingly wide range of functions and have become indispensable to modern life. Although most of their development in their current electronic form has happened over the past 20 years they have their origins in the mechanical calculating machines of the 17th-c.

Calculating machines are a very primitive form of computer in that they can only perform one arithmetic operation at a time, whereas computers can be programmed to perform a whole sequence of operations, using the answers from the first calculator as the input to the second and so on. This makes them infinitely more powerful than the humble calculator.

Among the first calculating machines were the 1624 'calculating clock' or Wilhelm Schickard (1592-1635), which could perform addition and subtraction, PASCAL'S calculator of 1642 and that of LEIBNIZ in the 1670s. Although Leibniz's invention used a stepped gear principle which became common in future designs, all of these were essentially curiosities rather than practical machines.Computer circuitry overview

In 1820 Thomas de Colmar (1785-1870) made a practical calculator which partially mechanized all four basic arithmetic operations, and in 1875 another major advance was made with the invention by the American Frank Baldwin (1838-1925) of the pinwheel, a gearwheel with a variable number of teeth.

These developments led In turn to perhaps the zenith or mechanical calculator technology, the 'comptometer' of Dorr Felt (1862-1930) in 1885, which was a reliable desktop calculator with the convenience of entering numbers by striking keys as on a typewriter. The comptometer became a standard office calculating machine until it was superseded by electronic devices in the 1970s.

While these were the forerunners of today's calculators, they still lacked the essential ability of the computer to perform a sequence of operations automatically. The first attempt at that was made by BABBAGE in 1834,who conceived, but never built, an 'analytical engine' capable of executing any series of arithmetic operations input via punched cards and to print the answer.
Sadly, and despite substantial financial backing and ingenious design, Babbage never saw any of his machines completed, and many of his ideas were subsequently reinvented by the pioneers of electronic computers in the 1940s. However, Babbage's machine was to store its instructions on punched cards, and this concept was turned into reality in the 1890s by HOLLERITH, who developed the idea into a practical means of storing data that could be read by mechanical calculating machines (for the American census, in his case). Hollerith went on to found a company to market his inventions, which subsequently grew to become IBM

Even with data storage, mechanical calculating machines were tar too slow to be of much practical value, and DE FOREST'S invention of the thermionic triode in 1907 sowed the seeds for a potentially much faster type of electronic calculator. A number of transitional machines marked the passage from mechanical devices to purely electronic machines, such as those of Konrad Zuse (1910-95), who between 1938 and 1945 used mechanical parts and electromechanical relays to make several automatic programmable calculators. In 1943 Howard Aiken (1900-73) devised a giant, electrically driven mechanical calculator, the Harvard Mark 1, which helped demonstrate that large-scale automatic calculation was possible.
Computer circuits in close up

It took the stimulus provided by the Second World War, however, together with the development at that time of the thermionic valve as a reliable and mass-produced device (for radio and radar), to open up a new range of possibilities for electronic machines. Many scientists and engineers made simultaneous developments in the history of the computer around this time.

Colossus, a British computer designed in 1943 specifically for code breaking work, first established the practical large-scale use of thermionic valves in computers, and the American ENIAC (Electronic Numerical Integrator And Computer) built in 1945 by John Mauchly (1907-80) and John Presper Eckert (1919-95) was designed to compute ballistics tables for the US army. Also involved in the ENIAC project was the mathematician VON NEUMANN, who went on to formalize the two essential components of the modern stored-program computer-a central processing unit (CPU) and the ability to hold the results of calculations in memory and use them in subsequent operations.

After the war many of these experimental machines began to be developed into commercial computers . In Manchester the first electronic stored-program machine was run in 1948, and a collaboration with the Ferranti Company resulted in a number of computers such as Pegasus (1956), Mercury (1957) and Atlas (1962). In Cambridge, WILKES built the EOSAC computer in 1949, which was developed in 1951 via a collaboration with the] Lyons Company into the first machine designed exclusively for business use, LEO (Lyons Electronic Office).

In 1946 at the National Physical Laboratory, London, TURING, a mathematician who had been involved in the wartime code-breaking work at Bletchley Park, designed ACE (Automatic Computing Engine). First run in 1950, ACE was commercialized as OEUCE by the General Electric Company in 1955. In the USA, Eckert and Mauchly founded the first electronic computer business and in 1951 produced their first UNIVAC computer. This was used to correctly predict the results or the us presidential election the following year, a widely televised feat which did much to popularize the computer.

The next step forward came in the early 1960s with the transistor, invented by SHOCKLEY, BARDEand BRATTAIN in 1947, which began to be utilized to make a new generation of compact and relatively power efficient machines. Even so, computer circuit boards were so large that their size and complexity limited overall speed and performance. In 1958 Sack Kilby (1923- ) of Texas Instruments established that a number of transistors could be manufactured on the same block of semiconductor material, and the following year Robert Noyce (1927-90) of rival Fairchild Semiconductors devised a way of interconnecting and integrating such components to form an integrated circuit, or 'microprocessor'.
Computer Motherboard
The next stage was to put most of the essential components or a complete computer on a single chip, and the resulting microrocessor was announced by Intel Corporation in 1971. This led to the pocket-sized calculators of the early 1970s and to the development of the desktop personal computer in 1977

Subsequent development in computer hardware has largely been one of continued refinement and miniaturization of the microrocessor components, with doubling of speed and decreasing price becoming routine. Recent developments in computing have increasingly focused on the software that runs on the computer, rather than the hardware itself.

Developments such as the graphical user interface (GUI), pioneered by Apple Computer, Inc., have made sophisticated computer systems accessible and useful to many people. In areas such as in mgn-geenn,advanced visualization techniques that use SD colour graphics to interactively display and analyse problems have become commonplace. The development of high-capacity data-storage devices such as CD-ROM has opened up another role for the computer in publishing and education, and the current development of fast public information networks and multimedia promises yet more uses, which will combine the traditional roles of computer, television and telephone. Today the 'computer' effectively embraces a host of devices and applications based on microrocessor technology, and few are used just for computing.

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