The document discusses input and output devices, which are peripherals connected to a computer's central processing unit. Input devices like keyboards and mice provide data to the computer, while output devices, such as printers and visual display units, present data in a human-readable form. It also categorizes printers into impact (dot matrix, letter quality, line printers) and non-impact (laser, inkjet) types based on their printing mechanisms.

1. Input / Output device
by
Dr. I. Uma Maheswari,
Email id: iuma_maheswari@yahoo.co.in

2. Input / Output Devices:
Certain devices called peripherals obtain communication
to or from the computer.
Peripherals are the units connected to the central
processing unit. They are
 input devices and
 Output devices.

3. Input devices:
The purpose of having input devices is to present data to
the computer.
The input devices feed the data in machine -readable
to the computer.
 Keyboard
 Mouse
 Disk

4. Output devices:
 The output devices are used to bring out the
from the computer in a human-readable form.
 Typical output devices are printers, plotters and
visual display unit.
 Besides, storage devices like magnetic tape and
magnetic disks are also used to output the results.

5. Printers
 Printers are the most common output devices used for
getting copy.
 There are different types of printers depending upon
the mechanism, speed and quality of printing.
 In certain printers some impression is made on the
printer ribbon making an impact on the paper. They
are called Impact Printers.
 Printers, which do not have any impact on the paper,
are non-impact printers.

6. Impact Printers are classified into
 Dot matrix printer
 Letter quality printer and
 Line printer
Non-Impact printers are classified into
 Laser printer and
 Ink Jet printer