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.

A keyboard typically has characters engraved or printed on the keys and each press of a key typically corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce letters, numbers or signs (characters), other keys or simultaneous key presses can produce actions or computer commands.

keyboards have between 80 and 110 keys, including ( Typing ,  numeric , function , control) keys .

Keys patterns :

1- QWERTY

known as QWERTY for its first six letters ,generally laid out in the same pattern used for typewriters, this layout helped keep mechanical typewriters’ metal arms from colliding and jamming as people typed.

2-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  where you place your fingers when you begin typing. People who prefer the Dvorak layout say it increases their typing speed and reduces fatigue .

3- AZERTY

AZERTY layout used in several  French-speaking countries, including France and Belgium. The French language uses several accented letters, such as é, à and ô, as well as a few other symbols such as œ that do not occur in English. A QWERTY keyboard is therefore insufficient.the swapping of letters was made to accommodate letter frequencies in French, which are different from English ones.for instance, the letter W is much rarer in French than in English, while Z is slightly more frequent.

How Keyboard works :

Keyboard has its own processor and circuitry that carries information to and from that processor.A large part of this circuitry makes up the key matrix.

The key matrix is a grid of circuits underneath the keys. In all keyboards each circuit is broken at a point below each key. When you press a key, it presses a switch, completing the circuit and allowing a tiny amount of current to flow through. The mechanical action of the switch causes some vibration, called bounce, which the processor filters out.

When the processor finds a circuit that is closed, it compares the location of that circuit on the key matrix to the character map in its  (ROM). A character map is basically a comparison chart or look up table. It tells the processor the position of each key in the matrix and what each keystroke or combination of keystrokes represents.

A computer can also use separate character maps, overriding the one found in the keyboard.

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