?What is a Computer
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.
a Computer logo
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.
?What is a Keyboard
A keyboard is a computer hardware input device. Originally based upon the design of the mechanical typewriter, computer keyboards have evolved with technological advances much as other computer hardware has evolved. New ergonomic keyboards can cost as much as a central processing unit or quality computer monitor. Besides the mouse, the keyboard is often the principal input device on home and office computers. Although primarily used for text input, keyboards are also used for precise image and interface manipulation, sending special commands to the operating system, and even controlling characters and objects in computer games. Some keyboards include other input/output features such as card readers, USB ports, or integrated trackballs. Although there are pseudo-standards regarding key arrangement, keyboard manufacturers are free to create original arrangements and designs. While most keyboards intended for use in English-language environments use the QWERTY layout, many keyboards are available with alternative layouts such as Dvorak. Some specialty keyboards have two or more layouts or languages printed on the keys, while others have no layout printed at all. These blank keyboards are intended for touch-typists only, who have no need to look at the keyboard while entering information.
Most conventional keyboards are built using dome-membrane technology. In these models, keys are mounted on a tray which affords them up and down movement only. The keys are supported in the up position by rubber membrane domes on which they rest. The domes are easily collapsible, and quickly return to their upright positions when released from the collapsing force. The underside of each dome houses a graphite bullet, which completes an open circuit underneath the dome when the dome is collapsed. Special circuitry senses the completed circuit, and translates this to a keypress which is then transmitted to the computer. Complex circuitry grids and patterns allow most keyboards to support over one hundred different keys with only about two dozen different circuits. In fact, careful layout of specific meta keys allows two- and even three- key-press combinations to be registered. More complex key-press combinations require very specialized circuitry, which few keyboards today support.
a Keyboard logo
In addition to standard flat keyboard layouts where all alphanumeric keys are grouped together, as was the case in virtually all typewriters, recent ergonomic keyboard designs feature creative key placement and shape. These keyboards are designed to increase user comfort, typing speed, and to reduce common ailments associated with prolonged keyboard use such as carpal tunnel syndrome. Most popular among the ergonomic keyboards is the split design, in which keys pressed by the left hand are physically separated from those pressed by the right hand. As much as ten centimeters may separate the key groups, providing a more natural hand position than a single group of keys does. Some ergonomic keyboards go so far as to offer two completely separate boards that can be positioned independently of one another. Other innovative keyboard designs include chorded keyboards, hand keyers, and Kanji tablets. Chorded keyboards typically have between 5 and 12 keys, which are pressed together in order to form letters in a fasion akin to guitar chording. Chorded keyboards are usually intended for one-hand use. Similar to the chorded keyboard is the hand keyer. While the operation of a hand keyer is comparable a chorded keyboard in that multiple fingers are used simultaneously in order to type a single letter, hand keyers are worn on the hand or arm instead of lying on a table. This makes them more comfortable for some users, as well as affording a certain amount of mobility for portable devices such as PDAs. Kanji and other tablets, which have super-small keying surfaces capable of supporting hundreds of characters in a reasonable amount of space, are designed for use with languages which have too many characters to assign an individual key on a conventional keyboard. This is typical of many Asian languages. Kanji tablets are now considered outdated, as more efficient text input systems have been designed which allow Asian character input on conventional-style keyboards. Keyboards designed for use with these systems have an additional 5 keys dedicated to interface with specialty character
input software.
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