Learn
how to use Computer Devices.
In the context of computer
technology, a device is a unit of hardware , outside or inside the case or
housing for the essential computer (processor, memory, and data paths) that is
capable of providing input to the essential computer or of receiving output or
of both. When the term is used generally (as in computer devices), it can include keyboards, mousse, display
monitors, hard disk drives, CD-ROM players, printers, audio speakers and
microphones, and other hardware units. Some devices such as a hard disk drive
or a CD-ROM drive, while physically inside the computer housing, are considered
devices because they are separately installable and replaceable. With notebook
and smaller computers, devices tend to be more physically integrated with the
"non-device" part of the computer.
Following are few 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 in inputting 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:
Sr.No
|
Keys
|
Description
|
1
|
Typing Keys
|
These keys include the letter keys
(A-Z) and digit keys (0-9) which generally give same layout as that of
typewriters.
|
2
|
Numeric Keypad
|
It is used to enter 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 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 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 mouse and sends
corresponding signals to CPU when the mouse buttons are pressed.
Generally it has two buttons called
left and right button and a wheel is present between the buttons. Mouse can be
used to control the position of cursor on 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 keyboard.
Joystick
Joystick is also a pointing device
which is used to move 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 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 which is
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 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 ball, 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 and a square.
Scanner
Scanner is an input device which works
more like a photocopy machine. It is used when some information is available on
a paper and it is to be transferred to the hard disc of the computer for
further manipulation. Scanner captures images from the source which are then
converted into the digital form that can be stored on the disc. 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 because it converts graphics and pictorial data into binary inputs. A
graphic tablet as digitizer is used for doing fine works of drawing and image
manipulation applications.
Microphone
Microphone is an input device to input
sound that is then stored in digital form. The microphone is used for various
applications like adding sound to a multimedia presentation or for mixing
music.
Magnetic Ink Card Reader (MICR)
MICR input device is generally used in
banks because of a 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 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 form of light and dark lines). Bar coded data
is generally used in labelling goods, numbering the books etc. It may be a hand
held 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 to which bar code reader is connected.
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.
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