InputAnd Output Unit
The computer will be of no use unless it is able to
communicate with the outside world. Input/output
devices are required for users to communicate with
the computer. In simple terms, input devices bring
information INTO the computer and output devices
bring information OUT of a computer system.
These input/output devices are also known as
An input device is any device that provides data to a
computer. Since the job of a computer is primarily to
process input, computers are pretty useless without input
devices. Just imagine how much fun you would have
using your computer without a keyboard or mouse. Not
very much. Therefore, input devices are a vital part of
every computer system.
Manual input devices need to be physically
operated. Some of the examples are:-
Manual Input Device
The basic input device through which you input
information into the system is called a computer
keyboard .The keyboard can be used to accomplish
many tasks .You can use a computer keyboard to type
out your documents, access menus, manipulate your
system and much more. Computer keyboards come in a
wide range of numbers, shapes, and sizes
A mouse moves the arrow on the screen and lets you
click things that help you get around the
computer, without this the computer would be useless.
You move it around and the sensor at the bottom lets
you control the arrow. Computer mice come in many
shapes and sizes but are all designed to fit either the left
or right hand. Mice communicate with the computer
either wirelessly or wired.
A camera is a device that is used to transfer an
image onto either a sheet of film or a space on a
digital hard drive. It does this by collecting light
that is reflected off an object and then creating
a copy of the image on whatever storage device
the particular camera uses.
A joystick is an input device commonly used to
control video games. It is something like a
mouse but it consist of a base and a stick that
can be moved in any direction.The stick can be
moved slowly or quickly and in different
amounts. Some joysticks have sticks that can
also be rotated to the left or right. Because of
the flexible movements a joystick allows, it can
provide much greater control than the keys on a
Automatic Input Devices
As well as manual, there are automatic input devices.
They require minimal human input – they are like
sensors. Here are some examples:-
Other type or input devices include magnetic
card reader.The magnetic strip behind the
credit card stores details about the card holder.
To input that information,The card is swiped
through the card reader.
MICR is used to read a specially designed
font, printed in magnetic ink, at the bottom of
every cheque. An MICR machine can read 300
cheques a minute.
The OMR (Optical Mark Reader)
automatically reads lottery tickets
and multiple choice exam papers. It
scans and recognizes the selected
box.Then as usual the results are
sent to a computer for processing.
OpticalCharacter Recognition, or OCR, is
a technology that enables you to convert
different types of documents, such as
scanned paper documents, PDF files or
images captured by a digital camera into
editable and searchable data.
Lines of different widths and sizes representing
data, that when read will determine what the
scanned object is. A perfect example of a
barcode reader is a super market barcode
scanner that reads and logs the price of a
Data generated by a computer is referred to as output.
This includes data produced at a software level, such as
the result of a calculation, or at a physical level, such as
a printed document.
Devices that produce physical output from the
computer are creatively called output devices.The most
commonly used output device is the computer's
monitor, which displays data on a screen.
TypesOf Output Devices
Some of the examples are:-
Monitors are display devices external to the computer
case and connect via a cable to a port on the video card
or motherboard. Even though the monitor sits outside
the main computer housing, it is an essential part of the
Monitors come in two major types - LCD or CRT. CRT
monitors look much like old-fashioned televisions and
are very deep in size. LCD monitors are much
thinner, use less energy, and provide a greater graphics
A computer printer is a computer peripheral
device that produces a hard copy from data
stored in a computer connected to it. A printer is
used to print anything that you want, like
pictures or documents or data.They plug in
where there is a USB slot, from there you can
click print and the document is sent to the port
where your document is printed.
A plotter is a printer that interprets commands from a
computer to make line drawings on paper with one or
more automated pens. Unlike a regular printer , the
plotter can draw continuous point-to-point lines directly
from vector graphics files or commands.
Plotters were the first type of printer that could print
with color and render graphics and full-size engineering
drawings. As a rule, plotters are much more expensive
Speakers are popular output devices used with
computer systems.They receive audio input
from the computer's sound card and produce
audio output in the form of sound waves. Most
computer speakers are active
speakers, meaning they have an internal
amplifier which allows you to increase the
volume, or amplitude, of the sound.