CHAPTER 3
· INPUT & OUTPUT DEVICE OF COMPUTER
v
Input Devices
· Input device is any peripheral (piece
of computer hardware equipment to
· provide data and control signals to
an information processing system such as a computer or other information
appliance.
· Input device Translate data from form
that humans understand to one that the computer can work with. Most common are
keyboard and mouse
¨
Following are some of the important input devices which are used in a
computer
1.
Keyboard
2.
Mouse
3.
Joy Stick
4.
Light pen
5.
Track Ball
6.
Scanner
7.
Graphic Tablet
8.
Microphone
9.
Magnetic Ink Card Reader(MICR)
10.
Optical Character Reader(OCR)
11.
Bar Code Reader
12.
Optical Mark Reader(OMR)
v Keyboard
Ø 
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.
v
Mouse
Ø 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.
v Joystick
Ø 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.
v Light Pen
Ø 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.
Ø 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.
v Track Ball
Ø 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.
v Scanner
Ø 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.
Ø 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.
v Digitizer
Ø
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.
v Microphone
Ø Microphone is an input device to
input sound that is then stored in a digital form.
Ø The microphone is used for various
applications such as adding sound to a multimedia presentation or for mixing
music.
v Magnetic Ink Card Reader (MICR)
Ø 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.
v Optical Character Reader (OCR)
Ø OCR is an input device used to read a
printed text.
Ø OCR scans the text optically,
character by character, converts them into a machine readable code, and stores
the text on the system memory.
v Bar Code Readers
Ø 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.
Ø 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.
Ø
v Optical Mark Reader (OMR)
Ø 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.
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