Computers are connected with input devices such as the keyboards, mouse, trackballs, joysticks,
touch screens, light pens, scanners, bar code readers etc. Input devices help Computer users to
input data into the Computer. Over the years input devices have undergone many changes and
improvements. One significant shift is from manufacture and use of wired input devices to wireless
input devices. Also addition of new functions have rendered the input devices more useful than
ever before. This article gives you an overview of input devices and focuses on some of the
technological changes that have taken place. In part one we discuss the Keyboard, the mouse,
the trackball and joystick, whereas, in part two we discuss the Touch screens, light pens, scanners
and bar code readers.

Keyboard

The keyboard resembles a typewriter and is the most important input device allowing us to enter
text and numbers into the computer. The keyboard layout which is most common is called as the
Qwerty layout. The Alternative layouts are the Drovak and the Standard layouts, but the Qwerty
layout has very much remained in vogue throughout these years.

Initially, the keyboard had 101 keys, inclusive of alphabetic, numeric, function and navigation keys.
However, additional keys were added in course of time. The addition of windows keys increased
the key count to 104.The windows keys such as the windows start and the right click keys give
added convenience for windows users.

More keys were added in the form of multimedia keys. These keys allow the keyboarders to
start and stop music or control the volume of sound with only a single key press. The Internet keys
were added to give convenience of starting and shutting down the email and browsing. The key
count in modern keyboards has increased and now we have keyboards having upto 130 keys.

Some special keyboards have also hit the market. They have specialised functions allowing easy
operation of special programs. The special keyboards have shortcut keys for certain types of
applications. For example, the photoshop keyboard has shortcuts for the photoshop application,
whereas the audio editing and video editing keyboards have shortcuts for audio and video
applications.

The wired keyboards use the standard keyboard connection, the PS/2 connection
or more recently the usb connection. In recent years, keyboards have switched over to wireless
types. The wireless keyboards use the wireless technology to get connected to the computer.
They use the Infrared (Irda) or the bluetooth standards to achieve wireless connectivity. The
wireless keyboards give greater freedom of operation for the users.

Mouse

A mouse is an important input device as far as the computer operation is concerned. As opposed to
text only input the mouse allows you to input graphical data into the computer. You can draw the
graphic elements such as the lines, curves and various other shapes, therefore, a mouse is a
a versatlie device for use of graphic designers. With the mouse, we can input data by clicking the right
and left buttons, double clicking or drag and drop operations.

The Mouse has also undergone many technological improvements over the years. Initially, the
mouse was purely Mechanical. It consisted of the ball and rollers and the signals from mechanical
sensors were carried to the computer by means of the wires.The mechanical mouse was not a very
reliable device. A better mouse was designed by replacing the mechanical sensors with the optical
sensors. This mouse is called as the opto-mechanical mouse. This was more reliable than the
mechanical mouse. However, the ball and roller mechanism still remained a mechanical one and
caused many problems. The mouse has now developed itself into a completely optical mouse. In the
optical mouse the ball and roller mechanism is replaced by a complete optical system.The
optical mouse is a more reliable device than the mechanical and the opto-mechanical mice.
 
Just like the keyboard there are wired mice and chordless mice . The initial wired mice used the serial
port to achieve the connectivity, but now wired mice use the USB port. The wireless mice use either the
irda or the bluetooth standard to achieve the connectivity. The wireless mouse allows a lot of freedom
to the the users to move the mouse around as compared to the wired mouse.

Trackball

Unlike  the mouse, the trackball has an exposed ball. Your thumb rests on the exposed ball
and your fingers move on the buttons. To move the cursor you have to move the ball with your thumb.
The main advantage of the trackball is that you don't have to move the entire device, like in the case of
the mouse and, therefore, it requires less space to operate. Trackballs have been extensively used
in computer notebooks. Computer gamers find the trackball to be faster as compared to the mouse.

Nowadays a combination of mouse with wheel and trackball is available. They are available as
either the Ps/2 wire model or bluetooth wireless model.  

Joystick

A Joystick works on almost the same principle as the mouse. Instead of the rollers, the joystick
employs pressure sensitive sensors to achieve horizontal and vertical movements. Modern joysticks
employ two axis or three axis sticks with a variety of  buttons. These joysticks are very popular with
gamers but they also find many military as well as industrial applications. The rugged variety of joysticks
are used to control  the aircrafts as well as different types of industrial machinery.The desktop joysticks
can be used to play shooting and firing games and the buttons can be used to control the shooting and
firing activities.

In the Part II we will take a look at the other input devices-- the touch screens, the light pens, the
scanners and the bar code readers.