4.4 INPUT DEVICES
In this section we will discuss various types of input devices used for entering data into
the computer system. These are:
4.4.1 Keyboard
It is the most common input device used for entering data and information into the
computer system. This is the standard input device attached to all computers. The
keyboard is a primary device for inputting text by pressing a set of keys. All the keys are
neatly mounted in a keyboard connected to the computer system. Keyboard devices can
be classified into two types general purpose keyboards and special purpose
keyboards. General purpose keyboard are standard keyboards used with most computer
system. They are called general purpose because that have enough keys to make them
useful for any type of application. The layout of keyboard is just like the traditional
typewriter of the type QWERTY. It also contains some extra command keys and function
keys. It contains a total of 101 to 104 keys. You have to press a correct combination of
keys to input data. The computer can recognize the electrical signals corresponding to the
correct key combination and processing is done accordingly.
The User can enter data into the computer by pressing a set of keys on the keyboard. In a
keyboard letters are printed on the keys. The first keyboard was developed in the 18th
century and was named as a QWERTY keyboard. A Computer keyboard includes
control circuitry which converts the key pressed by the user into key codes so that the
computer can understand it. Now-a-days wireless keyboards are also being used which
increase user freedom. The wireless feature is achieved by infrared signals or by radio
frequency
In general, a computer keyboard has following keys :
1. Alphanumeric Keys: It includes letters and numbers.
2. Punctuation Keys: These include comma, period, semicolon etc. and
3. Special Keys: These can be function keys, control keys, arrow keys and Caps
lock keys etc.
(a) Original PC keyboard having 84 keys;
(b) Advance Technology (AT) Keyboard having 101-104 keys; and
(c) Multimedia Keyboard having 120 – 140 keys.
4.4.2 Mouse
A Mouse is a handy device which can be moved on a smooth surface to cause the
movement of a cursor on the screen. It is a pointing device which is used to input data
and information into the computer system by pointing on it. Physically, a mouse contains
a small case, held under one of the user’s hands with one or more buttons. For GUI-based
systems a mouse is an essential pointing-device. The cursor of the mouse moves in the
same direction in which the mouse ball rolls.
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Its name is derived from its shape, which looks a bit like a mouse, with its connecting
wire that one can imagine to be the mouse’s tail. A Mouse rolls on a small ball and has
two or three buttons on the top. When you roll the mouse across a flat surface on the
screen, sensors sense the mouse in the direction of mouse movement. The cursor moves
very fast with a mouse giving you more freedom to work in any direction. It is easier and
faster to move through a mouse compared to movement using keys.
Types of Mouse
Mouse could be mechanical, optical or cordless types. Further information regarding
these types are as follows :
Mechanical Mouse : Mechanical Mouse uses ball for the movement of cursor on the
computer screen. When the ball is rolled in any direction, a sensor of the mouse detects it
and also moves the mouse pointer in the same direction.
Optical Mouse : Optical Mouse uses Laser rays for the movement of cursor on the
computer screen. It is an advanced pointing device. Movement is detected by sensing
changes in the reflected light rather than the motion of a rolling sphere.
Cord-Less Mouse : Cord-Less Mouse is battery driven and does not need any wire for
the physical connection with the motherboard. It transmits data through infrared or radio
signal.
Computer mice are very useful in designing pictures and graphs and computer and video
games by multimedia designers. A Mouse pad is required to move the mouse because it
provides a smooth surface. However, an optical or laser mouse doesn’t require a mouse
pad.
4.4.3 Digitizing (Graphic) Tablet
Digitizing or Ggraphics’ tablet is a computer input device that allows one to hand-draw
images and graphics, similar to the way one draws images with a pencil and paper. These
tablets may also be used to capture data of handwritten signatures. Some tablets are
intended as a general replacement for a mouse as the primary pointing and navigation
device for desktop computers. These are used by architects, engineers and designers in
Computer Aided Design (CAD) for designing purposes, such as buildings, cars,
mechanical parts, robots etc. These are also used in Geographical Information System
(GPS) for digitizing of maps.
Graphics tablet is most suited for artists and those who want the natural feel of a pen-like
object to manipulate the cursor on their screen. Wacom is the most well known
manufacturer of graphics tablets, and is incredibly well respected.
4.4.4 Trackball
Trackball is a moveable ball mounted on a stationary device, which can be rotated
manually by using fingers. It is also a pointing device. In a trackball, the ball is placed on
the top along with buttons which can be rolled with the fingers. These are used in playing
video games.
Mouse and mobile phones are equipped with trackballs to navigate addresses as well as
play games.
4.4.5 Joystick
Joystick is a remote control device for a computer which is used for playing video games
to indicate the position. It has a stick that pivots on a base and is used for controlling the
action in video games. The User moves a spherical ball with the help of a stick in the
joystick as opposed to the trackball where fingers are used for moving the ball.
Joysticks are also used for controlling machines such as cranes, trucks, underwater
unmanned vehicles, flight simulators, industrial robots etc.
👉Check Your Progress 2
3) What do you mean by scanners and what are their functions?
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4) What do you mean by joystick and trackballs in a computer system?
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