Computer
- Input Devices
Following are some of the important input devices which are used
in a computer −
- Keyboard
- Mouse
- Joy Stick
- Light pen
- Track Ball
- Scanner
- Graphic Tablet
- Microphone
- Magnetic Ink
Card Reader(MICR)
- Optical
Character Reader(OCR)
- Bar Code
Reader
- Optical Mark
Reader(OMR)
Keyboard
Keyboard is the most common and very popular input device which
helps to input data to the computer. The layout of the keyboard is like that of
traditional typewriter, although there are some additional keys provided for performing
additional functions.
Keyboards are of two sizes 84 keys or 101/102 keys, but now
keyboards with 104 keys or 108 keys are also available for Windows and
Internet.
The keys on the keyboard are as follows −
|
S.No
|
Keys & Description
|
|
1
|
Typing Keys
These keys include the
letter keys (A-Z) and digit keys (09) which generally give the same layout as
that of typewriters.
|
|
2
|
Numeric Keypad
It is used to enter the
numeric data or cursor movement. Generally, it consists of a set of 17 keys
that are laid out in the same configuration used by most adding machines and
calculators.
|
|
3
|
Function Keys
The twelve function keys
are present on the keyboard which are arranged in a row at the top of the
keyboard. Each function key has a unique meaning and is used for some
specific purpose.
|
|
4
|
Control keys
These keys provide cursor
and screen control. It includes four directional arrow keys. Control keys
also include Home, End, Insert, Delete, Page Up, Page Down, Control(Ctrl),
Alternate(Alt), Escape(Esc).
|
|
5
|
Special Purpose Keys
Keyboard also contains some
special purpose keys such as Enter, Shift, Caps Lock, Num Lock, Space bar,
Tab, and Print Screen.
|
Mouse
Mouse is the most popular pointing device. It is a very famous
cursor-control device having a small palm size box with a round ball at its
base, which senses the movement of the mouse and sends corresponding signals to
the CPU when the mouse buttons are pressed.
Generally, it has two buttons called the left and the right
button and a wheel is present between the buttons. A mouse can be used to
control the position of the cursor on the screen, but it cannot be used to
enter text into the computer.
Advantages
- Easy to use
- Not very
expensive
- Moves the
cursor faster than the arrow keys of the keyboard.
Joystick
Joystick is also a pointing device, which is used to move the
cursor position on a monitor screen. It is a stick having a spherical ball at
its both lower and upper ends. The lower spherical ball moves in a socket. The
joystick can be moved in all four directions.
The function of the joystick is similar to that of a mouse. It
is mainly used in Computer Aided Designing (CAD) and playing computer games.
Light Pen
Light pen is a pointing device similar to a pen. It is used to
select a displayed menu item or draw pictures on the monitor screen. It
consists of a photocell and an optical system placed in a small tube.
When the tip of a light pen is moved over the monitor screen and
the pen button is pressed, its photocell sensing element detects the screen
location and sends the corresponding signal to the CPU.
Track Ball
Track ball is an input device that is mostly used in notebook or
laptop computer, instead of a mouse. This is a ball which is half inserted and
by moving fingers on the ball, the pointer can be moved.
Since the whole device is not moved, a track ball requires less
space than a mouse. A track ball comes in various shapes like a ball, a button,
or a square.
Scanner
Scanner is an input device, which works more like a photocopy
machine. It is used when some information is available on paper and it is to be
transferred to the hard disk of the computer for further manipulation.
Scanner captures images from the source which are then converted
into a digital form that can be stored on the disk. These images can be edited
before they are printed.
Digitizer
Digitizer is an input device which converts analog information
into digital form. Digitizer can convert a signal from the television or camera
into a series of numbers that could be stored in a computer. They can be used
by the computer to create a picture of whatever the camera had been pointed at.
Digitizer is also known as Tablet or Graphics Tablet as it
converts graphics and pictorial data into binary inputs. A graphic tablet as
digitizer is used for fine works of drawing and image manipulation applications.
Microphone
Microphone is an input device to input sound that is then stored
in a digital form.
The microphone is used for various applications such as adding
sound to a multimedia presentation or for mixing music.
Magnetic Ink Card
Reader (MICR)
MICR input device is generally used in banks as there are large
number of cheques to be processed every day. The bank's code number and cheque
number are printed on the cheques with a special type of ink that contains
particles of magnetic material that are machine readable.
This reading process is called Magnetic Ink Character
Recognition (MICR). The main advantages of MICR is that it is fast and less
error prone.
Optical Character
Reader (OCR)
OCR is an input device used to read a printed text.
OCR scans the text optically, character by character, converts
them into a machine readable code, and stores the text on the system memory.
Bar Code Readers
Bar Code Reader is a device used for reading bar coded data
(data in the form of light and dark lines). Bar coded data is generally used in
labelling goods, numbering the books, etc. It may be a handheld scanner or may
be embedded in a stationary scanner.
Bar Code Reader scans a bar code image, converts it into an
alphanumeric value, which is then fed to the computer that the bar code reader
is connected to.
Optical Mark Reader
(OMR)
OMR is a special type of optical scanner used to recognize the
type of mark made by pen or pencil. It is used where one out of a few
alternatives is to be selected and marked.
It is specially used for checking the answer sheets of
examinations having multiple choice questions.
