This document discusses computer input and output devices. It describes various input devices like keyboards, mice, scanners and microphones that allow data and instructions to enter a computer. It also covers output devices such as monitors, printers and plotters that display or print data in human-readable form. Printers are divided into impact and non-impact types. The document provides details on the functioning and uses of different I/O devices.

1. Introduction to Computers
INPUT AND
OUTPUT
DEVICES

2. Introduction to Computers
Introduction
• Devices which are a means of
communication between the computer and
the outside world are called PERIPHERAL
DEVICES
• The processors which are required to
convert the input data into machine
readable form and to convert the output
generated by the computer into human
readable form are known as
INPUT/OUTPUT (I/O) interfaces.

3. Introduction to Computers
Input Devices
• Those peripheral devices which supply information i.e.
data and program from the outside world to the computer
are called INPUT DEVICES.
– Punched Cards
– Keyboard
– Mouse
– Light Pen
– Joystick
– Track Ball
– Touch Screen
– Digitizer
– Scanners
– Voice Recognition Systems

4. Introduction to Computers
Punched Cards
• Data is recorded on punched cards or tapes.
• It uses standard codes, like HOLLERITH code.
• Cheap and reliable.
• Cannot be reused.
• Special care has to be taken.
• If a single card is misplaced then it is very difficult to
rearrange and detect the problem.
• Require large storage space & cannot be folded.

5. Introduction to Computers
Keyboard
• Similar to typewriter keyboard.
• Keys on keyboard consist up of letters, numbers,
symbols and function keys.
• Special keys like Tab, Del, Ctrl, PgUp, PgDn,etc.
• Easy to use and offers number of facilities.
• Can edit the input data very easily.
• Relatively inexpensive.

6. Introduction to Computers
Mouse
• A pointing device.
• Control and manipulate cursor movement on monitor.
• Has three or four buttons on it and roller ball which
signals the movements on a flat surface.
• Move fast from one part of the screen to the other.

7. Introduction to Computers
Light Pen
• A picking device.
• Contains a photocell placed in a small tube.
• Photocell detect the presence of light on the CRT
(monitor).
• Tip of pen is moved on the surface of the screen to
write or sketch data.
• Specially useful in Computer Aided Design (CAD)
application

8. Introduction to Computers
Joystick
• Widely used in computer or video games.
• The direction and speed with which the joystick is moved
is converted into digital signal and sent to the computer
system.
• This in turn controls the movement of the cursor on the
screen.

9. Introduction to Computers
Track Ball
• Also known as roller ball.
• Uses a hard sphere to control cursor movement.
• Ball can be rotated in any direction by hand.
• This digital signal in translated to control the cursor
movement on the screen.

10. Introduction to Computers
Touch Screen
• A touch panel is transparent plate.
• Input is registered when a finger or any other object
comes in contact with the plate.

11. Introduction to Computers
Digitizer
• It converts a graphical or pictorial data into digital
form which can be directly entered and stored in a
computer.
• It is also called a graphical tablet.

12. Introduction to Computers
Flat Bed Digitizer
• The drawing to be digitized is fixed
over a flat bed table and a stylus or a
pen is moved over the surface of the
drawing.
• This scans the drawing and produces
the output related to X and Y
coordinate.

13. Introduction to Computers
Image scan digitizer
• The entire image is scanned and
reproduced automatically.
• It is more powerful as compared to flat bed
digitizers.
• It is mainly used in simple drawings,
graphs etc. whereas image scan digitizers
are used for photographs and pictures.

14. Introduction to Computers
Scanner
• It is able to directly enter text and images into the
computer memory.
• Eliminated the duplication work of entering data .
• This result into increase in speed of data entry
and accuracy.

15. Introduction to Computers
Optical Mark Reader
• Capable of reading pre-specified marks made by
pencils or pen with the help of light.
• Used where data is preprinted for application.
• Used for the answer papers of the objective tests where
the answers are marked with pencils or preprinted
forms.

16. Introduction to Computers
Optical Character Reader
• It can read alphabets, characters and numbers printed
on paper.
• Character can either handwritten or typed.
• It reads each character as a collection of pixels
• Mainly used in processing where the data volumes are
large.

17. Introduction to Computers
Bar Code Reader
• It reads bar coded data.
• Laser beam scanner is used to read the bar code.
• Most commonly used bar code is the Universal
Product Code (UPC).

18. Introduction to Computers
MAGNETIC INK CHARACTER
RECOGNITION (MICR).
• Mainly finds application in banking areas.
• It is used to encode the character to be read.
• It speed up data entry, and even roughly handled
cheques can be processed relatively easily.
• Only a limited number of digits and character are
available for encoding.

19. Introduction to Computers
Voice Recognition System
• Uses microphone or telephone, a sound card an
special software.
• Voice recognition system are highly operator
dependent.
• Reduces the cost of data entry.
• Can move freely while talking into the computer.

20. Introduction to Computers
Output Devices
• The output devices allow computer to
communicate with the outside world by accepting
data from the computer & transforming I into user
readable form.
– Printers
– Plotters
– Monitor
– Video Display Terminal
– Computer Output Microfilm

21. Introduction to Computers
Printer
• It produces the output from the
computer on the paper.
• Produces a hard copy i.e. permanent
copy of the result which can be stored
and read later.
–Impact Printers
–Non-Impact Printers

22. Introduction to Computers
Impact Printer
• Similar to typewriter.
• Use hammer to strike a character against
an ink ribbon.
• Noisy in operation.
• Its functioning is relatively easily.
• It can produced multiple copy at the same
time.
• Subject to wear and tear of mechanical
parts

23. Introduction to Computers
Dot Matrix Printer
• Print each character as a pattern of dots.
• Relatively low in cost.
• Print at speed 50-500 character per second.

24. Introduction to Computers
Daisy Wheel Printer
• Also called as letter quality printers
• Letter quality of these printer is much superior as
compared to the dot matrix printer
• They are slow and typically print in the range of 10-50
characters per second

25. Introduction to Computers
Line Printer
• Very fast printer and print at speed of 200-2500 lines
per second.
• It normally have 132 print positions per lines.
• It is normally used in application where large
volumes of data are to be printed

26. Introduction to Computers
Ink Jet Printer
• Prints character by spraying ink from tiny nozzles onto the
paper.
• Output is of a superior quality.
• Possible to obtain coloured output.
• Number of character styles and sizes are available.

27. Introduction to Computers
Laser Printers
• Produced a very superior quality output.
• Have a buffer memory to store entire pages and hence their speed is
very fast.
• No mechanical movement is involved.
• Noiseless in operation.
• Comparatively expensive

28. Introduction to Computers
Plotter
• A plotter is a an output device used in
applications where printouts of graphs and
drawings are required
• Plotters are of two types
– Flat Bed Plotter
– Drum Plotters

29. Introduction to Computers
Flat Bed Plotters

30. Introduction to Computers
Drum Plotters

31. Introduction to Computers
Monitors
• Monitor is a device like television screen
which is used to display information
• The resolution of monitors is the number
of picture elements
• Monitors are of two types
– Cathode Ray Tube Monitor (CRT)
– Flat Panel Display

32. Introduction to Computers
Cathode Ray Tube Monitor

33. Introduction to Computers
Flat Panel Display

34. Introduction to Computers
Video Display Terminal
• The most popular output device in direct
access processing is the Video Display
Terminal
• The Monitor & Keyboard together are
called a Terminal
• 3 types of terminals
– Dumb
– Smart
– Intelligent

35. Introduction to Computers
Computer Microfilm Output (COM)
• This technology is used to record computer output
as a microscopic film images.
• Information is recorded on a roll of film.
• COM devices are used applications where there are
large volumes of data.
• They are much more faster than normal printers
• Sophisticated & Expensive

36. Introduction to Computers
Thank You!!