| Keyboards -
Computer Keyboards. The set of typewriter-like keys that enables you to enter data
into a computer. Computer keyboards are similar to electric-typewriter keyboards but
contain additional keys. The keys on computer keyboards are often classified as follows:
alphanumeric keys -- letters and numbers punctuation keys -- comma, period, semicolon, and
so on. special keys -- function keys, control keys, arrow keys, Caps Lock key, and so on.
The standard layout of letters, numbers, and punctuation is known as a QWERTY keyboard
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because the
first six keys on the top row of letters spell QWERTY. The QWERTY keyboard was designed in
the 1800s for mechanical typewriters and was actually designed to slow typists down to
avoid jamming the keys. Another keyboard design, which has letters positioned for speed
typing, is the Dvorak keyboard.
There is no standard computer keyboard, although many manufacturers imitate the keyboards
of PCs. There are actually three different PC keyboards: the original PC keyboard, with 84
keys; the AT keyboard, also with 84 keys; and the enhanced keyboard, with 101 keys. The
three differ somewhat in the placement of function keys, the Control key, the Return key,
and the Shift keys.
In addition to these keys, IBM keyboards contain the following keys: Page Up, Page Down,
Home, End, Insert, Pause, Num Lock, Scroll Lock, Break, Caps Lock, Print Screen.
There are several different types of keyboards for the Apple Macintosh. All of them are
called ADB keyboards because they connect to the Apple Desktop bus (ADB). The two main
varieties of Macintosh keyboards are the standard keyboard and the extended keyboard,
which has 15 additional special-function keys.
Alphanumeric: Describes the combined set of all letters in the alphabet and the numbers 0
through 9. It is useful to group letters and numbers together because many programs treat
them identically, and differently from punctuation characters. For example, most operating
systems allow you to use any letters or numbers in filenames but prohibit many punctuation
characters. Your computer manual would express this rule by stating: "Filenames may
be composed of alphanumeric characters."
Sometimes additional characters are considered alphanumeric. For example, on IBM
mainframes the characters @, #, and $ are considered alphanumeric characters.
Qwerty Keyboard: Pronounced kwer-tee, refers to the arrangement of keys on a standard
English computer keyboard or typewriter. The name derives from the first six characters on
the top alphabetic line of the keyboard. The arrangement of characters on a QWERTY
keyboard was designed in 1868 by Christopher Sholes, the inventor of the typewriter.
According to popular myth, Sholes arranged the keys in their odd fashion to prevent
jamming on mechanical typewriters by separating commonly used letter combinations.
However, there is no evidence to support this assertion, except that the arrangement does,
in fact, inhibit fast typing.
With the emergence of ball-head electric typewriters and computer keyboards, on which
jamming is not an issue, new keyboards designed for speed typing have been invented. The
best-known is called a Dvorak keyboard. Despite their more rational designs, these new
keyboards have not received wide acceptance.
Dvorak Keyboard: A keyboard designed for speed typing. The Dvorak keyboard was designed in
the 1930s by August Dvorak, a professor of education, and his brother-in-law, William
Dealy. Unlike the traditional QWERTY keyboard, the Dvorak keyboard is designed so that the
middle row of keys includes the most common letters. In addition, common letter
combinations are positioned in such a way that they can be typed quickly. It has been
estimated that in an average eight-hour day, a typist's hands travel 16 miles on a QWERTY
keyboard, but only 1 mile on a Dvorak keyboard.
In addition to the standard Dvorak keyboard, there are two additional Dvorak keyboards, a
left-handed and right-handed keyboard. These keyboards are designed for people who have
only one hand for typing.
AT Keyboard: An 84-key keyboard introduced with the PC /AT. It was later replaced with the
101-key Enhanced Keyboard
Enhanced Keyboard: (1) A 101- or 102-key keyboard from IBM that supersedes the keyboard
for the PC /AT computer. The most significant difference between the enhanced keyboard and
previous models is that the enhanced keyboard has a row of 12 function keys at the top
instead of 10 function keys grouped on the left side of the keyboard. Nearly all PCs made
today come with an Enhanced Keyboard. (2) For Macintoshes, see under extended keyboard |
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