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The keys can be used individually or in combination with other keys. The keyboard normally
contains 101 to 108 keys, which can be classified as follows:
◦ Alphanumeric keys (A-Z, a-z, 0-9)
◦ Control keys (Ctrl, Alt, Esc, etc.)
◦ Function keys (F1-F12)
◦ Special keys (Caps Lock, Backspace, Spacebar, Arrow keys, Home, End, etc.)
◦ Punctuation keys (“ , ” , “-”, ; , etc.)
Depending on the position or placement of the keys, the layout of a keyboard comes in various
styles such as QWERTY, QWERTZ, AZERTY and DVORAK. QWERTY keyboard is the most
commonly used keyboard. It is based on the English language. Its name is derived from the
sequence in which six alphabetical keys are positioned on the upper line of the keyboard. AZERTY
type keyboard is mostly used in France (‘A’ and ‘Z’ characters replace ‘Q’ and ‘W’ on such
keyboards). QWERTZ type keyboard is widely used in Germany and Central Europe.
• Mouse: It is a handheld pointing device which is used on a flat surface
and is represented by a pointer on the screen. The pointer on the screen
moves when the mouse is moved by the user. A mouse generally consists
of two buttons and a scroll wheel on its top. It allows you to put data
into a computer by using point, click, and drag and drop commands. It
controls the movement of the pointer on the screen. It is used to move and select icons, files,
and folders on your computer. There are two main types of mouse: optical and mechanical.
An optical mouse is an advanced computer pointing device that uses a light-emitting diode
(LED) and an optical sensor. This type of mouse does not require any internal cleaning since
there are no rotating parts. However, they can get sticky over time as dust collects near the
light emitter. This can cause erratic cursor movement or prevent the mouse from working.
You must clean the surface of the mouse and the mouse pad regularly to prevent dust from
accumulating on the mouse.
A mechanical mouse uses a rubber ball that makes contact with wheels inside the
unit when it is rolled on a pad. This type of mouse is especially susceptible to dust
and particles that can accumulate inside the mouse, which can make it difficult to
track or move properly. If the mouse pointer does not move smoothly, you will
have to clean the rubber ball.
• Scanner: A scanner is a device that scans a document by sensing the reflection that is received
when the scanner emits rays on the contents. It takes the image of contents and converts it
into a digital file.
The scanned image or photo can be stored in a computer and easily transferred to a secondary
storage device. Scanners can be categorized as ‘Hand held scanner’ and ‘Flatbed scanner’.
◦ Hand-Held Scanner: It is a type of scanner that can be held in hand and
rolled over a flat image or document. It is used to scan documents into
digital forms. Scanners of this type are small in size, portable and less
expensive.
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Computer—Hardware Components

