1. Input and
Output
devices

2. Input devices
Some input devices are :
•Keyboards
•Track point
•Mouse
•Barcode reader
•Touch screens

3. keyboards
In computing, a keyboard uses an arrangement of buttons
or keys, to act as mechanical levers or electronic switches. The
keyboards became the main input device for computer.
Advantages:
•Most computers come with a keyboard.
•People are used to using keyboards to enter data.
•A skilled typist can enter data very quickly.
Disadvantages:
•It is easy to make mistakes when typing in data.
•If you can’t touch type, it can take time to enter data.
•Keyboards are not suitable for creating diagrams.

4. Track Point
A Track Point, is a cursor control device found in IBM
think pad, notebook, computers.
Advantages :
•It requires no extra space, since it is inbuilt within
the keyboard. Thus , it is ideal were little or no space
is available.
Disadvantages:
•It takes a practice in order to learn how to
coordinate the correct amount of pressure on the
track point.

5. Mouse
A mouse controls a pointer on the monitor. It enables you to control
what happens on the screen by moving the mouse on your desktop
and pointing, clicking and selecting items on the screen.
Advantages :
•Ideal for use with desktop computers.
•Works well in conjunction with a keyboard for data entry.
•Using a mouse to select items on the screen is faster than using a
keyboard.
Disadvantages:
•It is not easy to input text while using a mouse.
•They need a flat space close to the computer.
•Overuse can lead to repetitive strain injurey.

6. Barcode Reader
Barcode readers are like scanners which use laser beams in order to
read barcodes. A barcode reader is used to read the barcode by
using a visible red light.
Advantages :
•The process of data entry is fast and accurate.
•Barcodes can be printed by normal printing methods.
•No need to write down the name of the item and its price- all
are retrieved automatically.
Disadvantages:
•If there is dirt or any marks on the barcode, then the barcode
reader may be unable to read it.
•Only numbers can be coded.

7. Touch Screens
A touch screen is an input device because it allows the user to
use his/her finger in order to touch the preferred option.
Advantages:
•No training is required.
•No extra peripherals such as mouse are needed.
Disadvantages:
•Not ideal to put in large amounts of data.
•Not very accurate.
•Only the items already on the screen can be selected.
•Not robust-can soon become faulty if misused

8. Output devices
An example of an output Is a printer but there are different types of
printers:
•Character printer : prints one character at a time.
•Page printer: prints one page at a time
•Line printer: prints one line at a time.

9. Character printer
In character printers there are different groups such as
impact and non-impact. Also there are different types of
each groups.
Impact non-impact
dot matrix thermal
Daisy wheel inkjet
Golf ball

10. Impact printers
Golf ball printer : a golf ball printer uses a rotating ball as
a head. On the surface of this ball, there are letters and
when this ball strikes the ribbon, the character is imprinter
on the paper
Daisy wheel printer : the daisy wheel printer uses a wheel as its
print head. These are character shapes formed on each spoke
of the wheel. The wheel is rotated until the required character
is found, and then a hammer strikes the spoke onto the ribbon
against the paper
Advantages : Diasdvantages:
You can change fonts you have to change wheel to change fonts.
Relatively good quality slow
noisy
no graphics

11. Impact printers
Dot matrix printer : the dot matrix printer has a
number of pins in its head. These pins are configured in
such a way so as to form a shape. These pins hit the
ribbon into the paper. Thus, all character are made up
of a pattern of dots. The more pins the better the
resolution
Advantages : disadvantages:
Cheap simple graphics
Easy maintenance low quality
Can print graphics slow
noisy

12. Non- impact printers
Thermal printer: thermal printers work by heating certain areas
of the thermal paper. When this paper passes over the thermal
print head, the paper turns black at heated areas, thus
producing a printed image.
Inkjet printer : inkjet printers work by placing extremely small
droplets of ink onto the paper, thus creating an image/
character
Advantages : disadvantages :
Quiet good quality paper needed
Fast ink may be smudged
Cheap
Good quality

13. Page printer
In page printers there is only one group and that is non-
impact. In the non-impact group there Is one printer and
that is laser printer.
Laser printer : A laser printer is a common type
of computer printer that rapidly produces high quality
text and graphics on plain paper.
Advantages: disadvantages:
High quality of printouts colour laser printers are expensive
Fast: they print 1 page at time expensive maintenance
Quiet : no impact

14. Line printer
A line printer has one group : impact printer . The impact printer is
divided into two the drum printer and the chain printer.
Drum printer : drum printers use a rotating drum with
character shaped on it. This printer also consists of a
hammer set, where there Is a hammer for each character
position on the line. these hammers hit the paper onto
the ribbon and presses it against the drum. This type of
printer is used for checking printing.

15. Line printer
Chain printer : chain printers use a chain with character shaped
on it. This chain rotates and the hammer strikes the paper onto
that character as it passes. This type of printer is commonly used
for payroll listing.
Advantages : disadvantages:
Fast can’t print graphics
Reliable
Can handle large volumes of printouts

16. The end
by
kelsey attard
3.2