A keyboard's primary function is to act as an input device.
Using a keyboard, a person can type a document, use keystroke
shortcuts, access menus, play games and perform a variety
of other tasks. Keyboards can have different keys depending
on the manufacturer, the operating system they're designed
for, and whether they are attached to a desktop computer or
part of a laptop. But for the most part, these keys, also
called keycaps, are the same size and shape from keyboard
to keyboard. They're also placed at a similar distance from
one another in a similar pattern, no matter what language
or alphabet the keys represent.
Most keyboards have between 80 and 110 keys, including:
A numeric keypad
The typing keys include the letters of the alphabet, generally
laid out in the same pattern used for typewriters. According
to legend, this layout, known as QWERTY for its first six
letters, helped keep mechanical typewriters' metal arms from
colliding and jamming as people typed. Some people question
this story – whether it’s true or not, the QWERTY
pattern had long been a standard by the time computer keyboards
Keyboards can also use a variety of other typing key arrangements.
The most widely known is Dvorak, named for its creator, August
Dvorak. The Dvorak layout places all of the vowels on the
left side of the keyboard and the most common consonants on
the right. The most commonly used letters are all found along
the home row. The home row is the main row where you place
your fingers when you begin typing. People who prefer the
Dvorak layout say it increases their typing speed and reduces
fatigue. Other layouts include ABCDE, XPeRT, QWERTZ and AZERTY.
Each is named for the first keys in the pattern. The QWERTZ
and AZERTY arrangements are commonly used in Europe.
numeric keypad is a more recent addition to the computer keyboard.
As the use of computers in business environments increased,
so did the need for speedy data entry. Since a large part
of the data was numbers, a set of 17 keys, arranged in the
same configuration found on adding machines and calculators,
was added to the keyboard.
The Apple keyboard's control keys include the "Command"
1986, IBM further extended the basic keyboard with the addition
of function and control keys. Applications and operating systems
can assign specific commands to the function keys. Control
keys provide cursor and screen control. Four arrow keys arranged
in an inverted T formation between the typing keys and numeric
keypad move the cursor on the screen in small increments.
The Windows keyboard adds some extra control keys: two Windows
or Start keys, and an Application key. Apple keyboards, on
the other hand, have Command (also known as "Apple")
keys. A keyboard developed for Linux users features Linux-specific
hot keys, including one marked with "Tux" the penguin
-- the Linux logo/mascot.
Keyboards use a variety of switch technologies. Capacitive
switches are considered to be non-mechanical because they
do not physically complete a circuit like most other keyboard
technologies. Instead, current constantly flows through all
parts of the key matrix. Each key is spring-loaded and has
a tiny plate attached to the bottom of it. When you press
a key, it moves this plate closer to the plate below it. As
the two plates move closer together, the amount of current
flowing through the matrix changes. The processor detects
the change and interprets it as a key press for that location.
Capacitive switch keyboards are expensive, but they have a
longer life than any other keyboard. Also, they do not have
problems with bounce since the two surfaces never come into
actual contact. All of the other types of switches used in
keyboards are mechanical in nature. Each provides a different
level of audible and tactile response -- the sounds and sensations
that typing creates. Mechanical key switches include: