1. INPUT & OUTPUT ofINPUT & OUTPUT of
systemsystem

2. Input Devices
• The data or instructions you type
into the computer are called input
• Input devices used to get data into a
system.
• Get data into a system as accurately,
least amount of time.
• It’s a cheap device.

3. Examples of Input
Devices
• Keyboard
• Mouse
• Tracker ball
• Touch sensitive pad
• Joystick
• Light pen
• Touch screen
• Graphics tablets
• Magnetic Strip Reader
• Bar Code reader
• Digital cameras
• Web Cameras
• OCR
• MICR
• OMR
• Punched Card
• Kimball tag
• Voice recognition
• Microphone
• EPOS
• EFTPOS
• Video digitiser
• Scanner
• Touch Phone Telephone

4. 1.Keyboard
• Keyboard is the oldest and most familiar of all
input devices
• Keyboard are intelligent devices and contain their
own chips.
• The microprocessor scans the keyboard hundreds
of second to see if a key has been pressed .
• The CPU translate that key and convert into
ASCII code.
• A standard keyboard called QWERTY keyboard.

5. Concept or Ergonomic
Keyboard
• New keyboards, called concept
keyboards, have been developed
for ergonomics
• The goal of this keyboard is to
provide comfort and safety.
• The user who spends a lot of time
in typing may experience repetitive
injuries of wrist and hand.
• Higher typing speeds can be
achieved.

6. Cordless keyboard
• That requires no wires
• It is also called wireless keyboards.
• It transmits data using wireless
technology like radio waves or light
waves

7. Special keyboards
• These keyboards make it easy for blind
users to input data into a computer
• There are also keyboards with large
coloured keys that are easier to see.
• Each key is about one inch square.

8. Advantages
• Most computers come with a
keyboard supplied
• People are used to using keyboards to
enter data, they need very little
training
• A skilled typist can enter data very
quickly
• Specialist keyboards are available
e.g. ergonomic, gaming keyboards

9. Disadvantages
• It is easy to make mistakes when
typing in data
• If you can't touch type, it can be
time consuming to enter data
• Keyboards are not suitable for
creating diagrams
• Disabled people often find keyboards
difficult to use
• Excessive use can lead to R.S.I.

10. 2.Mouse
• That translate its movement on the
desktop into digital information.
• Moving the mouse produces
movement of cursor or the pointer on
the screen.
• The mouse is also provided with
buttons to press.

11. Technologies
• Movement of ball bearing is used to
produce electrical signal.
• Small lights under the mouse are
reflected on the photoelectric cells.

12. uses
• To select options from a menu or
form a set of icons
• To position the cursor when editing
text or using a design package.
• To draw shapes.
• It selects a position on the screen
more quickly than is possible with a
keyboard.

13. 3.Joysticks
• Is similar to tracker ball.
• Is a device which enables the user to control
movement on the screen by a small lever.
• The lever can be moved in any direction.
• Some joysticks give more control on the screen.
Uses
• Controlling objects in computer games
• Producing graphics
• Scanners in hospitals

14. 4.Light Pen
• Is a pen shaped device, held in the hand
which can detect the presence or absence
of light
• It is connected by the cable to a recording
device or to a computer or computer
terminal.
• Electrical signals are sent along the cable
indicating whether or not light of
sufficient intensity is being sensed.

15. Uses
• To detect bar codes
• To indicate a point on the screen
• It removes the need to type or write.
• It is faster than typing.
Disadvantage:
It can only record the presence or absence
of light.
It only works with software written for it.

16. 5.Graphics Tablet
• Is also known as digitizing or digitizing
pad.
• The digitize data means to convert it from
analog form to digital.
• A design is put on the board and its shape
is traced out with the stylus.
• Electrical signals sent to the computer
record the position of the stylus.
• Encoding the picture into binary form

17. Uses
• It can be used to digitize drawings
with great accuracy.
• Reproducing drawings and designs
• Producing layouts of printed circuit
boards.
• Digitizer Maps.

18. 6.Touch Pad /Track Pad
• Is a small, flat surface over which the user
moves his finger.
• The movement of the finger moves the
cursor on the screen.
• A touch pad also has one or more buttons
near it .
• These buttons like mouse buttons.
• Touch pads are commonly used with
notebook computers

19. Touch screen
• Is a video display screen that
receives input from the touch of
finger
• Examples
• ATM
• Petrol Pumps

20. Magnetic Strip
• Is a short length of magnetic tape stuck on the
surface of a tag, card or document.
• On plastic tags or cards the strip is sealed in.
• Tags with stripes identify the item they are
attached to.
Examples:
• On credit card
• On bank cards
• A phone Card
• Cash issue Terminals

21. Advantages
• It is simple to produce.
• It is not easily damaged.
• It stores a large no of characters.
Disadvantages
• The data can be changed or erased
by magnetic field.

22. 7.Barcodes Readers• Is set of parallel printed lines of differing
thickness, which represent a number.
• The number represented by the bars is also
printed above or below the bar code.
• When bar code are used on shop goods, the
number coded identifies the product and have
following information
1. Country of region
2. Manufacturer
3. An item number for the product.
Examples:
• Used in Barcodes
• Library System
• Warehouse stock

23. Advantages
• Printed easily
• The type of item or its price does
not have to be repeatedly written
down or typed.
Disadvantages:
• bar codes cannot be changed and
thus there are unsuitable prices.
• Bar codes only be read by machine.
• Only numbers can be coded in this
way.

24. 8.Optical Card reader
(OCR)
• Is a technology that reads typewritten , computer
printed or handwritten documents.
• It translate the image into a form that can be
recognized by computer.
• OCR devices read printed characters using OCR
font.
• An OCR device determines the shapes of
characters by detecting patterns of light and
dark.

25. Uses
• In department stores
• To scan financial documents such as
company

26. 9.Optical Mark
Recognition (OMR)
• It is also called mark sensing device.
• It uses light to scan input data to convert
it into electrical/digital signal.
• The signals are then sent to the computer
for further processing.
• Examples
• Voting ballot
• Multiple choice answer sheet marking
• Enrollment forms

27. Mark sheet (OMR)

28. Advantages
• In OMR there is typing involve so errors and
takes time is less
• Reduces the cost of inputting large amount of
data
• The method is useful when results of the test
are needed very quickly
• Disadvantages
• Readers are very expansive
• Only certain fonts are acceptable.
• There is high rejection rate

29. 10.Magnetic ink
character reader
(MICR)
• Characters are printed using
an ink containing iron oxide.
• As the document passes into
the reader the ink is
magnetized, so that the
character shapes can then be
recognized electrically.

30. Use
• It is used by banks industry for check
processing.
• Each check contains MICR characters
at the lower left edge.
• These characters represent check
number ,bank number and account
number
Branch codeCheque number Account number

31. Advantages
• Documents can still be read when
folded, written on
Disadvantages
• Readers are very expansive
• Only certain fonts are acceptable.

32. 11.Punched cards
• Contains holes in different positions which
mean something when they are read by a
reader.
• Punched cards were the main method of
entering data into computers.
• Example:
• The clock card which is used to record the
hours a person works so that wages can be
calculated.

33. 12.Kimball tag
• Kimball tags are the small cards with
holes punched in them that you see
attached to clothing in certain shops.
• When you buy the goods, one of the
tags is removed and sent for
processing to a computer centre.

34. Advantage
• Stock is reordered without any
writing or typing the data.
• Disadvantages:
• They are small and are easily mislaid.

35. Voice Recognition
• Using a microphone human speech is
coded into a sequence of electrical
signals.
• The computer searches a set of
stored patterns for the sound which
has been input
• It is now popular for inputting data
into word processing or database
packages.

36. Advantage
• Useful for handicapped people with
limited movement
• No typing or data preparation is
necessary.
Disadvantage:
• Few words can be recognized and the
error rate is high.
• Not suitable in noisy places.

37. 13.Microphone
• Is used for input device for a speech
recognition system.
• The voice pattern of user is then
converted into instructions to the
operating system or application
software or text.
• Uses as voice mail messages

38. 14.Electronic point of
sale Terminal (EPOS)
• Are the cash registers which act as
the terminals to a main computer
system
• Providing customers with item used in
bills.
• Give useful management information

39. 15.Electronic Fund
transfer at point of sale
(EFTPOS)
• Similar to EPOS terminal but some
additional features.
• They are able to transfer funds from
your bank account directly to a
store’s switch card called a debit
card.
• Example:
• Switch card

40. Advantage
• You can use it instead of a cheque.
• Faster method of payment
• Money is instantly transferred into its
account.
• You can also get cash back using your debit
card.
Disadvantage:
• They may be stolen and they are said to
encourage people to spend more money.

41. 16.Video Digitizer
• Is the combination of hardware and Software that converts
an analogue video signal into a digital signal in computer’s
memory
• Is used to convert a frame from a video sequence into a
picture
• Each frame from the video is converted using video
digitiser.
• It may be played back in any required sequence.
• Is also called image grabbing or frame grabbing
• Take up a lot of main memory and when stored use a large
amount of disk space

42. Uses
• Digitiser pictures Can be printed in a
magazine or document
• To make television adverts and to
produce pop videos.

43. 17.Scanner
• Read data or information from the
source
• Source could be written document, a
price tag, a graphics image , or
photograph
• To scan text or images which
manipulated in some way before being
printed

44. Types of Scanner
• Optical Scanner
• Optical Reader

45. Optical Scanner
• It is a light sending input device.
• The scanner image depend upon resolution
• Image will be sharper if the scanner provides high
resolution
• it provide OCR Software
• Different types of Optical Scanner are
• Flatbed Scanner
• Sheetfed Scanner
• Handheld Scanner

46. 18.Digital Camera
• Is used to store, picture in digital form.
• Store images using different ways like floppy
disk, memory stick, mini CD ,PC Card and micro
device.
• Can be connected to a computer easily through
USB port.
• Image resolution for digital camera measured by
megapixels.
• Higher resolution photo takes up more memory .

47. Advantages
• No film is needed
• No expensive developing costs
• Pictures are in digital form so it can
easily sent over the internet
• You can adjust the size of image

48. 19.Web camera ( Web
Cams)
• Is simply a digital camera
that is used to capture still
images and video images
• These images can then be
transmitted to a computer
where they are stored in
graphics format
• Pictures can be used on the
websites
• Camera placed on top the
screen such a system allow
video conferencing

49. Uses
• Advertising
• Checking on children in nurseries
• Checking on the weather on the other
part of the world

50. 20.Touch tone
Telephones
• Having a different tone of each
number when pressed key
• Using these different tones that the
numbers dialed are recognized and
routed to correct telephone
• Can be used as a data entry device
• Home banking system use touch tone
telephone

51. Output Device
• Output device provide results in a
suitable form after data processing.
• Output devices are used to get data
out of a system.
• They should be able to do this as
accurately and quickly as possible,
and with the minimum of human
intervention.

52. Output Device
– Visual devices (including Visual Display
Units [VDUs], screens, and monitors)
– Hard copy devices (including ink jet
printer, laser printers, dot-matrix
printers, and plotters)
– Sound devices
– Computer controlled devices (including
robots)

53. Monitor or VDU
• Most common output deice
• It is known as display screen
• The output display by monitor is
called soft copy so it is ideal for
showing the results from an enquire
where no printed is needed.

54. Features of Monitor
• Size
• Color
• Resolution
• Video Display Adapter

55. Types of Monitor
• CRT
• Flat Panel Monitors
• Touch screen Monitors

56. Cathode Ray Tube (CRT)
• Creates the image on the screen
through electronic beam
• This is same type that is use in
Television
• It consists of one or more guns
• These guns generate red ,green and
blue (RGB) colors.

57. Liquid Crystal Display
(LCD)
• LCD screens are most often seen on
portable or laptop computers
• These are used in these applications
because they are small and light.
• Also used where space is at the premium.
• The molecules this substances line up in
such a way that the light behind the
screens and creates an image.
• Use in banks and Multinational companies

58. Graphical Display unit
( GDU)
• Larger than VDU and have greater
resolutions
• lines on the screen don’t look as
through they are made up of lots of
tiny dots.
• Are often used in conjunction with
light pens

59. Printers
• It prints character ,symbols and
graphics on paper.
• Print resolution is commonly
measured in dots per inch (dpi)
• Different types of printer are
• Impact Printer
• Non Impact Printer

60. Impact Printer
• Its act like a typewriter
• It prints characters or images by
striking a print hammer or wheel
against an inked ribbon
• Dot matrix printer
• Line printer
• Daisy wheel Printer

61. 1.Dot Matrix printer
• It produces printed images when tiny pins on a
print head strike an inked ribbon
• When ribbon pressed against the paper, it
creates dots that they form characters and
graphics
• Which can transfer print through layers of paper.
• Able to print multi-part sheet where
• It generates lot of noise ,its print quality is not
good

62. 2.Line printer
• Is a fast impact printer
• It prints a entire line at a time
• Its speed is measured in line per
minute

63. 3.Daisy wheel printer
• Similar to typewriter
• Uses print wheel
• A motor rotates the wheel.
• Its slower than Dot matrix but
better in quality

64. 2. Non Impact Printer
• Prints characters and graphics on a
piece of paper without striking the
paper.
• These printers are faster than
impact printers
• Inkjet printer
• Laser printer
• Thermal printer

65. 1.Inkjet printer
• It prints characters and graphics by
spraying tiny drops of liquid ink on paper
• The print head of an inkjet printer
consists of nozzles
• It has two cartridges black and white
• These printers can produce quality text
and graphics in both black and white color
• slower than laser printer but faster than
dot matrix printer
• They can print 1 to 6 pages per minute
• Cheaper in price
• Satisfactory in color

66. 2.Laser Printer
• Creates image on the paper by the
laser beam
• Also called page printer because they
print complete page at a time
• It contain toner
• Throws magnetic powder on paper in
the form of microscopic dots

67. Advantages
• Print a page at a time so it is fast and
it print pages 10ppm
• They produce high quality of text
and graphics
• They are quiet in operation compared
with dot matrix
• Equipped with paper trays for both
the input and the output papers

68. Disadvantages
• Are more expensive than dot matrix
or ink-jet printer
• They are quite large and can take up
lot of disk space
• Quite complex so the repair bills can
be high
• Multi part stationary cannot be used

69. Thermal printer
• Is a printer that uses heat process
to transfer colored dyes or inks to
the paper
• Is the best color printers currently
available but it is very expensive

70. Plotters
• Is an output device that is used to produce
image quality graphics in variety of colors
• Used to create maps, architecture
drawings, graphs and charts
• A plotter works by drawing lines on paper
using pens held in a mechanical arm
• It may be in form of
• Flatbed Plotter
• Drum plotter

71. Plotters
• Is an output device that is used to produce
image quality graphics in variety of colors
• Used to create maps, architecture
drawings, graphs and charts
• A plotter works by drawing lines on paper
using pens held in a mechanical arm
• It may be in form of
• Flatbed Plotter
• Drum plotter

72. Flatbed Plotter
• Used to plot or draw images.
• It contains pens for drawing images.
• The paper is placed on table like
surface
• Software instructs the pens to move
down on the paper

73. Drum Plotter
• Uses a rotating drum
or cylinder
• The drawing pens are
mounted on the drum
• The pens move to the
left and right as the
drum rotates
• Advantage of drum
plotter is that the
length of the plot is
almost unlimited

74. Voice Output
• Visually people find the spoken word
from the computer
• Special software is used for this
process
• In a word processor each letter is
typed and it can hear with
headphone.

75. Audio Output
• An audio device translate audio
information from the computer into
sounds that people can understand
• Speakers
• Headsets

76. Electrical Signals
• Sometimes the output from one computer system can simply
be a series of electrical signal
• In this case one computer is being used as a terminal and
work that is done sent as electrical signals
• Electrical signals can be output and used to control all kinds
of devices such as
• Heating system
• Alarms
• Robots
• Actuators
• Computer aided manufacturing (CAM)
• Computerised numerical control (CNC)

77. Computer controlled
devices - Robots
A typical computer
controlled device
used in computer-
aided
manufacturing – a
robotic arm