INPUT DEVICES
What is Input?
Input is simply anything which you are entering into a computer. But technically speaking, input is a process by which human enters data which that is readable and then this data is transformed into a form that is machine-readable. The data that is entered into a computer is also referred to as, Input. All the documents from where we get the data which are entered into the computer are known as Source Document.
What are Input devices?
The devices that are used to enter data into a machine and then transformed into a form which is readable by the machine are known as input devices. There are so many input devices available in the market, but in this article we will discuss only few of them that are most commonly used by people.
Manual Input Devices:
- Keyboard
- Mouse
- Trackball
- Joystick
- Touch Pad
- Touch-sensitive screens
- Light pen
- Graphic pen/tablet
Keyboard
It is the most common input device used by every user having the computer. There is a classification of the keyboard on the basis of keys. Initially, there were keyboards which had 83/84 keys known as conventional keyboard. Now there are keyboards available in the market which contains more than 100 keys, known as enhanced keyboards. These extra keys perform different functions.
Classification of the keys on the keyboard is divided into three categories, namely; alphanumeric keypad, numeric keypad, and the function keys.
The arrangement of the keys on the keyboard is in QWERTY form which is similar to a typewriter.
Mouse
Because today is the era of GUI, the mouse is so much necessary today. It works as an alternative to keyboard. It is a pointing device and is used for many programs and mostly for games and drawing programs.
Normally, a mouse has two or three buttons and a ball at the bottom. When the mouse is moved on the mouse pad the cursor of the mouse also moves in the same direction on the screen. And after placing the cursor on the target position, the user presses the button and then the desired function is performed.
A mouse which has a ball at the bottom is adjusted in sphere and this sphere contains some wheels. When the user moves the mouse the ball moves the wheel and so the cursor on the screen also moves. There is also an optical mouse available in the market in which the computer senses the position of the mouse and then immediately sends the message to the computer, and then the computer moves the position of the cursor according to the message. Nowadays, another category, which is wireless mouse, is also available.
Trackball
It is also a pointing device which is just like a mouse but has a larger ball on the upper side. One thing that is different is that it requires no extra space for movement, whereas a mouse requires some free area to move in. It is not commonly used and also not so popular.
Joystick
It is also a pointing device used mainly for playing games. It contains a lever which controls the movement of the cursor on the screen. The joystick sends the signals about the position and speed of the lever to move the cursor in any direction.
Touch Pad
It is also used as an alternative to a mouse. It contains a pressure sensitive area which sends signal to the computer, and the computer accordingly moves the position of the cursor. This device is commonly seen in laptops as a built-in device.
Touch Sensitive Screen
It is a special kind of screen which senses the finger or any other object that touches it. It is commonly known as ‘Touch-Screen”. It was very costly in the past but nowadays, it is used in mobile phones and ATM machines, etc.
Light Pen
As we know, touch-screen is itself touch sensitive but there is another technology which is used as an alternative to the touch-screen, that is a light pen.
A light pen can be used on any screen. A light pen is a device which is used to make selections, place objects or to identify directions simply by touching the screen with a pen. A light pen contains a photosensitive detector at its tip which sends signal to the computer about the position of the pen on the screen. It is very useful for drawing purposes.
Graphic Pen and Tablet
It is also a pointing device. It is also known as digitizer and has the same function as the light pen. It is mainly used in textile designing and other drawings. Graphic tablet is a special pad on which the user uses the graphic pen to draw the objects on the screen. Graphic tablet is also pressure sensitive. If the user wants to draw a thick line, the more the pressure the user will exert, the thicker the line drawn on the screen will be.
