A computer is a device that accepts user input, processes it, and returns output. Usually, the modern use of the term computer refers to an electronic device that accepts input via keyboard and mouse, and returns output via a CRT or LCD monitor. Other input and output devices associated with today's common computer include hard disks, optical and flash storage, network connections, speakers, joysticks, and paper printers. Also, computers today are used for much more than the processing of raw data. Standard home computers are often used for communicating via the Internet, word processing, audio / video media management, and game playing. Specialized fields have discovered thousands of other uses for computers, and the devices are being introduced to new fields almost daily.
Different types of personal computers include desktop systems (PC's), notebook computers, handheld computers, and a few hybrid combinations of these. More specialized small computers are found in wristwatches, medical and factory monitors, automobile control systems, microwave ovens, and literally thousands of other applications. These are usually referred to as embedded systems, as the computer involved is not the primary component of the device. Large, very specialized computers are used in physics research, military intelligence, weather prediction, and other specialized fields. These machines are often called mainframes, a name that pays homage to the large frame encompassing early models.
There is no universal consensus on the identity of the first computer. While many historians are content with crowning the Roman or Chinese abaci as the earliest of computers, the devices themselves performed no information processing. Thus, an abacus does not display the defining property of a computer. The earliest known device that did in fact process information automatically was the Jacquard loom. The head of the Jacquard loom read punch cards, determined the locations of holes in the cards, and in response altered the pattern being woven by the loom. In addition to processing data, the loom was programmable by means of replacing the punch cards. Thus, the Jacquard loom performed two of the most important defining functions of computers: data processing, and the ability to be programmed.
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