INTRODUCTION
In computing, an input device is any peripheral (piece of computer
hardware equipment) used to
provide data and control signals to an information processing system such as a computer or other information appliance.
Many input devices can be classified according to:
·
modality of input (e.g. mechanical
motion, audio, visual, etc.)
·
the input is discrete (e.g. key
presses) or continuous (e.g. a mouse's position, though digitized into a
discrete quantity, is fast enough to be considered continuous)
·
the number of degrees of freedom
involved (e.g. two-dimensional traditional mice, or three-dimensional
navigators designed for CAD applications)
Pointing devices, which are input devices used to
specify a position in space, can further be classified according to:
·
Whether the input is direct or
indirect. With direct input, the input space coincides with the display space,
i.e. pointing is done in the space where visual feedback or the pointer appears.Touchscreens and light pens involve direct input. Examples involving indirect input include the
mouse and trackball.
·
Whether the positional information is
absolute (e.g. on a touch screen) or relative (e.g. with a mouse that can be
lifted and repositioned)
Direct input is almost necessarily absolute, but
indirect input may be either absolute or relative. For example, digitizing graphics tablets that do not have an embedded screen
involve indirect input and sense absolute positions and are often run in an
absolute input mode, but they may also be set up to simulate a relative input
mode like that of a touchpad, where the stylus or
puck can be lifted and repositioned.
.
TOPIC CONTENT
Keyboard
Most common and very popular input device is
keyboard. The keyboard helps in inputting the data to the computer.The layout
of the keyboard is like that of traditional typewriter, although there are some
additional keys provided for performing some additional functions.
Keyboard are of two sizes 84 keys or 101/102 keys,
but now 104 keys or 108 keys keyboard is also available for Windows and
Internet.
The keys are following
|
Sr. No.
|
Keys
|
Description
|
|
1
|
Typing Keys
|
These keys include the letter keys
(A-Z) and digits keys (0-9) which are 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 machine and calculators.
|
|
3
|
Function Keys
|
The twelve functions keys are present
on the keyboard. These are arranged in a row along the top of the
keyboard.Each function key has unique meaning and is used for some specific
purpose.
|
|
4
|
Control keys
|
These keys provides cursor and screen
control. It includes four directional arrow key.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. It is a small palm size box with a round ball at
its base which senses the movement of mouse and sends corresponding signals to
CPU on pressing the buttons.
Generally it has two buttons called left and right
button and scroll bar is present at the mid. 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.TheJoystic can be moved in all four directions.
The function of joystic 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 light pen's tip 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 a digital form. Digitizer can convert a signal from the
television 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 images
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.
