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 calculation 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’ of Wilhelm Schickard (1592–1635), which could perform addition and subtraction, calculator of 1642 and that of 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. 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 of 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 The comptometer became a standard office calculating machine until it was superseded by electronic devices in the 1970s.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 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 , 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 far too slow to be of much practical value, and 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.

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 , 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, built the EDSAC computer in 1949, which was developed in 1951 via a collaboration with the J Lyons Company into the first machine designed exclusively for business use, LEO (Lyons Electronic Office). In 1946 at the National Physical Laboratory, London, , 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 DEUCE 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 of 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 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 Jack 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 ‘microchip’. The next stage was to put most of the essential components for a complete computer on a single chip, and the resulting ‘microprocessor’ 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 microprocessor 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 engineering, advanced visualization techniques that use 3D colour graphics to interactively display and analyse problems have become commonplace. The development of high-capacity data-storage devices such as CD-ROM and DVD 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 microprocessor technology, and few are used just for computing.