Nov 9, 2012


A device that converts our information to a form which computer understands is known as an input device. These devices are necessary to convert our information into some other forms which a computer can understand. A keyboard terminal is the most common input device.
Example-Mouse, Keyboard, Scanner, Joystick, Trackball, Light pen, BCR, MICR, OCR etc.

It is a pointing device used in a computer system to select an object. In mouse, we found two buttons named left and right click.Left click is used to select an object and right-clicks to display "popup" menu and in between there is a scroll wheel to scroll the page up and down.


There are two types of mouse -------        
A>Scroll mouse      B>Optical mouse

It is the most important input device used in a computer system to enter a character, number, operator, symbol, and others.


ESC: This key is used to get escape from "pop-up" menu.
BACKSPACE: Use to erase the previous character from the current position.
SPACEBAR: Use to create a blank space after the current position.
ENTER: To accept or select an object.         
NAVIGATION KEYS: These keys are used to navigate the pointer to left-right, up and down.
PAGE UP AND DOWN KEYS: This page up and down key is used to scroll the page up and down by keyboard.
DELETE: This key is used to delete an object.
NUMLOCK: Is Numlock is on there we can type the number from numpod and if Numlock is off we cannot type the number from numpod.
CAPSLOCK: If Capslock is on then we can type the character in capital letter and if Capslock is off we can type the character in small letter.

According to the key layout, keyboard is of two types -------

According to the key function, keyboard is of two types ------- 

A>Normal keyboard  
B>Multimedia keyboard                                                       

The scanner is an input device used to scan an image and text and send it to computer memory. These pictures can be altered, re-sized and printed as required.


Types of Scanner------
A>Flatbed Scanner
B>Hand-Held Scanner
C>Drum Scanner
D>Planetary Scanner
E>3D Scanner

An input device that utilizes a light-sensitive detector to select objects on a display screen. A light pen is similar to a mouse except that with a light pen you can move the pointer and select objects on the display screen by directly pointing to the objects with the pen.


Trackball, a pointing device, is a mouse lying on its back. To move the pointer, you rotate the ball with your thumb, your fingers or the palm of your hand .there are usually one to three buttons next to the ball, which you use just like mouse buttons. The advantage of trackballs over the mouse is that the trackball is stationary so it does not require much space to use. Trackballs are most popular pointing devices for portable computers.

A joystick lets the user move an object on the screen.children play games on computers using a joystick. In some of these games, the user has to move objects in various directions. A keyboard for this purpose is not convenient for small children. They can use a joystick more easily. A joystick, as shown in the figure above, can be moved left or right, forward or backward. These movements are sensed by a potentiometer. the movements are translated into binary instructions with the help of electrical contacts in its base. A joystick is generally used to control the velocity of the screen cursor movement rather than its absolute position.  


It is a special type of screen which apart from taking the input, also displays the output. This screen is sensitive to human touch and is basically made up of plasma. For functioning, the user has to touch a specific part of the screen containing the pictorial form of the command to be executed. This type of device is very costly.


Various commodities available in the market have a sequence of black and white lines of varying thickness, closely placed together printed on the cover. These lines, which are known as Barcodes, contain various information about the product, name of the product, date of its manufacture, producer's name, expiry date, cost of production etc. The Barcodes have the same meaning throughout the globe and are hence it is also known as Universal Product Code(UPC). To read the information contained in Barcodes through the computer, Barcode readers are employed. Barcode readers find popular applications in departmental stores.  
Barcode reader

This input device allows users to enter audio signals into the computer for being stored, edited or for playing them back in future. This device produces analog signals which are changed to digital signals by an inbuilt mechanism called digitizer. Voice input is preferred for multimedia machines and data entry terminals. 

Voice input

A digitizer or digitizing tablet is an input device used in map making. The tablets, which come in different sizes are used as the working surface. A grid of many tiny wires is connected to the computer. Drawings placed over this grid can be traced and entered into the computer by the use of a special pen or mouse-like device. This device has crosshairs and opens and closes electrical circuits in the grid and thus identifies X-Y coordinates. Original drawings may also be entered. The drawing is displayed on the screen as it progresses which can later be stored or printed out. Design and engineering businesses such as those that develop aircraft or computer chips also use digitizers. 



This is very informative article for IT student.

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