Keyboard

How It Works

A keyboard consists of two parts: a set of keys that are pushed in sequence by the typist (or keyer) and an encoder that identifies each pressed key and generates a code that uniquely identifies that key. The key set includes the standard alphanumeric keys found on old typewriters and additional keys, such as cursor keys, navigation and function keys, Apple or Windows keys, and a numeric keypad. Keyboards for laptop computers have the minimum number of keys.

The encoder is a microprocessor located in the keyboard that detects each key as it is pressed and released. To do so, the encoder maintains a set of signals in a grid of intersecting rows and columns. When the typist presses a key, a connection is made on the grid. If, for example, the connection is in the first row and the third column, the encoder immediately identifies the pressed key and sends a special signal, called a "scanning code," to the computer. The computer translates the scanning code into the appropriate binary code and displays the character on the monitor so that the typist can verify that the correct key was pushed.

The lights on the keyboard (for Caps Lock, Num Lock, Scroll Lock, and so on) are controlled by the computer, not the keyboard. For example, when the typist presses the Caps Lock key, the keyboard encoder sends the code for the Caps Lock key to the computer, and the computer turns on the keyboard's Caps Lock light.

Key Arrangement

The computer keyboard is based on the layout of early typewriters. Until the late nineteenth century, typewriter keys were arranged in alphabetical order. In 1872 Christopher Latham Sholes (1819–1890) developed the first typewriter, which featured the QWERTY keyboard (pronounced "kwer-tee"), so named because the first six letters near the top left of the keyboard are Q-WE-R-T-Y. The new layout was designed to slow down fast typists and place the keys most likely to be hit in rapid succession on opposite sides of the typewriter. This was done so that the machine would be less likely to jam.

The arrangement resolved the jamming problem, but it created two others. First, many common letters are not located on the center row, also called the "home row." Second, some of the most common letters are concentrated on the left side, favoring left-handed typists. For example, the most common letter, "E," is a stretch for the left middle finger, and the second most common letter, "A," is typed with the left hand's weakest finger.

The QWERTY keyboard continues to be featured on the vast majority of computer keyboards in English-speaking countries even though the reason for its creation, to minimize typewriter jamming, ceased to be relevant with the invention of electric typewriters and computers.

Dvorak Keyboard

August Dvorak patented an alternative English-language layout in 1936. The top row has p, y, f, g, c, r, and l. The middle row has a, o, e, u, i, d, h, t, n, and s. The bottom row has q, j, k, x, b, m, w, v, and z. (Illustrations of the Dvorak layout are available at http://www.microsoft.com/GLOBALDEV/keyboards/keyboards.asp) Dvorak, a professor at the University of Washington, claimed that his layout could speed typing by approximately 35 percent. The Dvorak keyboard is considered by some to be a more efficient design because it concentrates the most-used keys on the center row of the keyboard. Advocates claim that Dvorak's layout allows 70 percent of the keystrokes to take place on the center row, compared to 35 percent with the standard QWERTY layout.

Although QWERTY is by far the most widely used layout, some popular operating systems (such as those by Microsoft and Apple) have a built-in option to accommodate Dvorak as well as QWERTY keyboards. In addition, one-handed Dvorak layouts are available for typists using only the right or the left hand.

Multilingual Keyboards

Many operating systems include support for keyboard layouts for non-U.S. typists. For example, Microsoft Windows operating systems support dozens of "locales"—a locale determines how the computer accommodates regional language and conventions such as keyboard layout, sort order, currency format, and date, time, and number format.

Some non-U.S. language keyboards are electronically identical to those produced for U.S. customers, but they have special key caps and a special software program, called a driver, to translate each keystroke into the appropriate symbol for that language. For example, a Thai-language keyboard would need a Thai driver to translate keystrokes into the correct Thai characters.

Ergonomic Keyboards

Ergonomic keyboards were developed to address hand, wrist, and arm ailments common among typists. Awkward wrist positions can lead to muscle, tendon, and nerve damage in the wrists (carpal tunnel syndrome) and forearms because of diminished blood supply or compression caused by inflamed tendons.

Ergonomic keyboards claim to reduce the incidence of repetitive stress injury, including carpal tunnel syndrome, by positioning the keys for each hand in a more natural position for the typist's arms, wrists, and hands. Ergonomic keyboards include wavy keyboards, split keyboards, and separate keypads.

Keyboard operators should pay special attention to ergonomic factors in their work environment. The chair and keyboard should be positioned so that the typist can sit up straight with feet flat on the floor and both arms able to move freely without hitting the armrests or becoming fatigued.

SEE ALSO ERGONOMICS.

Ann McIver McHoes

Bibliography

Beeching, William A. Century of the Typewriter. New York: St. Martin's Press, 1974.

Clements, Alan. The Principles of Computer Hardware. New York: Oxford University Press, 1985.

Current, Richard N. The Typewriter and the Men Who Made It. Arcadia, CA: Post-Era Books, 1988.