THE FOLLOWING IS A LIST OF THE MOST COMMON INPUT
DEVICES WHICH ARE NOWADAYS FOUND IN A COMPUTER SYSTEM:
3RD JOY STICK
4TH LIGHT PEN
5TH TRACK BALL
7TH GRAPHIC TABLET(DIGITIZER)
9TH MAGNETIC INK CARD READER(MICR)
10TH OPTICAL CHARACTER READER(OCR)
11TH BAR CODE READER
12TH OPTICAL MARK READER
Input is any data or instructions entered into the memory of a computer.
input device is any hardware component that allows a user to enter data and
instructions into a computer.
Different categories of keys in
1. TYPING KEYS These keys include the letter keys (A-Z) and digits keys (0-9) which
generally give same layout as that of typewriters.
I t is used to enter numeric data or cursor movement. Generally, it
of a set of 17 keys that are laid out in the same configuration used by
adding machine and calculators.
The twelve functions keys are present on the keyboard. These are
in a row along the top of the keyboard. Each function key has unique
meaning and is used for some specific purpose.
These keys provides cursor and screen control. I t includes four
arrow key. Control keys also include Home, End, Insert, Delet ,page up,
page down Control(Ctrl), Alternate(Alt), Escape(Esc).
Keyboard also contains some special purpose keys such as Enter,
Caps Lock, Num Lock, Space bar, Tab, and Print Screen.
Working of keyboard:
When any key is pressed in
keyboard, the spring blow
presses down thus completing
the circuit. The tiny chip
notes which key is being
pressed. It sends interrupt
request to the O.S.it also
sends a code called scan code
to the KEYBOARD BUFFER the
system software respond to
the interrupt by reading scan
code this scan code is
WORKING OF MOUSE:
There is a small ball underneath a mouse , the
ball moves too. As the ball moves it rubs
against two rollers.One roller senses the
horizontal movement and other vertical.
These rollers together can tell in which
direction the user moves the mouse. Each
roller is attached to a wheel called ENCODER.
This encoder turns with the rollers.As the
encoder turns, its metal bridges touches two
fixed electrical contact which generates
electrical pulses.The movement of mouse
tells with which rate the electrical pulse is
generated.These signals are send to the
computer through mouse cables.These
signals are read by software called the
MOUSE DRIVER. this software tells your
computer how to move mouse pointer so that
it matches mouse movement.
‘Joystick is also a pointing device which is used to move
cursor position on a monitor screen. ’
4th LIGHT PEN:
‘they are pen shaped devices are used to select the screen icons by detecting
the light coming from the CRT screen.’
5th TRACK BALL:
A trackball is a stationary pointing device with a ball
on its top.
‘Ascanner is a light-sensing input device that convertsprinted text and
graphicsinto a digital form that can be furtherprocessed by the computer’
TYPES OF SCANNER:
1.flat bed scaner,2.hand held
Working of a scanner:
Scanners operate by shining light at the object or document being
digitized and directing the reflected light (usually through a
series of mirrors and lenses) onto a photosensitive element. In
most scanners, the sensing medium is an electronic, light-sensing
integrated circuit known as a charged coupled device (CCD). Light-
sensitive photosites arrayed along the CCD convert levels of
brightness into electronic signals that are then processed into a
Two other technologies, CIS (Contact Image Sensor), and PMT
(photomultiplier tube) are found in the low and high ends of the
scanner market, respectively. CIS is a newer technology that
allows scanners to be smaller and lighter, but sacrifices dynamic
range, depth-of-field, and resolution. PMT-based drum scanners
produce very high-quality images, but have limited application in
Another sensing technology, CMOS (Complementary Metal Oxide
Semiconductor), appears primarily in low-end, hand-held digital
cameras where its low cost, low power consumption and easier
component integration permits smaller, less expensive designs.
GRAPHIC TABLET (DIGITIZER):
‘A graphics tablet or digitizer is a computer input device that enables
a user to hand-draw images and graphics, similar to the way a person
draws images with a pencil and paper’.
‘a microphone is an input device that convert sound into electrical
MAGNETIC INK CARD READER (MICR):
‘Magnetic ink character recognition (MICR) is a character-recognition
technology used mainly by the banking industry to ease the processing
and clearance of cheques and other documents’.
‘Its the mechanical or electronic conversion of scanned images of
handwritten, typewritten or printed text into machine-encoded text’.
BAR CODE READER:
‘A barcode reader (or barcode scanner) is an electronic device for
reading printed barcodes’.
OPTICAL MARK READER (OMR):
‘Optical mark recognition (also called optical mark reading and OMR) is
the process of capturing human-marked data from document forms such as
surveys and tests’.