Computer WORLD

It is difficult to identify any one device as the earliest computer, partly because the term «computer» has been subject to varying interpretations over time. Originally, the term «computer» referred to a person who performed numerical calculations (a human computer), often with the aid of a mechanical calculating device.

The history of the modern computer begins with two separate technologies – that of automated calculation and that of programmability. Simple examples of information-processing machines can be traced back to ancient times. The following are some of the more important forerunners of the computer.

The abacus is the counting frame that was the most widely used device for doing arithmetic in ancient times and whose use persisted into modern times in the Orient. Early versions of the abacus consisted of a board with grooves in which pebbles could slide.

The «castle clock», an astronomical clock invented by Al-Jazari in 1206, is considered to be the earliest programmable analog computer. It displayed the zodiac, the solar and lunar orbits, a crescent moon-shaped pointer traveling across a gateway causing automatic doors to open every hour, and five robotic musicians who play music when struck by levers operated by a camshaft attached to a water wheel. The length of day and night could be re-programmed every day in order to account for the changing lengths of day and night throughout the year.

In the seventeenth century, calculators began to appear. Blaise Pascal and Wilhelm von Leibniz usually are singled out as pioneers. The calculator Pascal and Leibniz built were unreliable, since the mechanical technology of that time was not capable of manufacturing the parts with sufficient precision. As manufacturing techniques improved, mechanical calculators were perfected. They were widely used until they were replaced by electronic calculators in recent times.

Most information-processing machines were designed to do arithmetic. An outstanding exception was Jacquard’s automated loom, a machine designed not for hard figures but beautiful patterns. A Jacquard loom weaves cloth containing a decorative pattern. The woven part was controlled by punched cards. Changing the punched card changed the pattern the loom wove. 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. Jacquard looms came into widespread use in the early nineteenth century, and their descendants are still used today.

Дата добавления: 2015-11-14