INPUT DEVICE
An input device is
any device that provides input to a computer. There are dozens of possible
input devices, but the two most common ones are a keyboard and mouse. Every key
you press on the keyboard and every movement or click you make with the mouse
sends a specific input signal to the computer. These commands allow you to open
programs, type messages, drag objects, and perform many other functions on your
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.
While most
computers come with a keyboard and mouse, other input devices may also be used
to send information to the computer. Some examples include joysticks, MIDI
keyboards, microphones, scanners, digital cameras, webcams, card readers, UPC
scanners, and scientific measuring equipment. All these devices send
information to the computer and therefore are categorized as input devices.
Peripherals that output data from the computer are called output devices.
The input unit is
formed by the input devices attached to the computer. Ex - Keyboard, Microphone
etc. An input unit takes the input & converts it into binary form so that
it can be understood by the computer.
KEYBOARD
This is most commonly
used device which acts as input device. Its structure is like typewriter.It
contains no. of keys which have some specific ASCII values. Like ‘A’ has
ASCII value 65. When this is pressed , it is converted into 65 & this 65 is
sent to CPU in the form of Binary language (i.e. 1000001). Then operations are
done on this data.
MOUSE
This is a pointing
device which contains a roller in its base. When the mouse is moved on any
surface, the pointer on the screen is also moved. It contains a potentiometer
coupled with the roller. This potentiometer senses the motion of mouse &
convert it into digital value. A mouse may contain two or three buttons.
Now a day's optical
mouse are very popular.
BAR CODE READER
It is a device
which is used to read the code from the products which are usually in the form
of Bars. It contains a light sensitive detector which identifies the values of
the bars on the product & converts them into numeric code.
These Bar readers
are used in Shopping malls in a very large scale.
DIGITAL CAMERA
As the name
specifies, these camera stores the data digitally, which then can be stored in
the computer & can be stored for a long time. But it has very limited
storage capacity. These are very popular because of less expensive photographs
& Speed.
LIGHT PEN
It is a pointing
device which contains a photocell mounted at its tip. It senses the light from
the screen when it becomes closer to the screen, & generates a
pulse. So for identifying a particular location on the screen these light pens
are very useful. But this is not in very much use these days.
SCANNER
The scanner is an
input device like the photocopier machine which makes the electronic copy of
the picture or document which can be further edited.
MIC's or
MICROPHONES
The scanner is an
input device like the photocopier machine which makes the electronic copy of
the picture or document which can be furth.
CAMERA
Most cameras like
this are used during live conversations. The camera transmits a picture
from one computer to another, or can be used to record a short video.
COMPACT DISC (CD)
CDs store information.
The CD can then be put into another computer, and the information can be opened
and added or used on the second computer.
Note: A CD-R
or CD-RW can also be used as an OUTPUT device.
JOYSTICK
A joystick is used
to move the cursor from place to place, and to click on various items in
programs. A joystick is used mostly for computer games.
TOUCH SCREEN
A touch screen is a
computer screen or other screen that you can touch with your finger to enter
information. Examples of touch screens include a smart board, a
microwave, a dishwasher, or an ATM at a bank.
