Data Entry Devices/Input Devices

Input Devices

Input devices are necessary to convert our information or data into a form that can be understood by the computer. A good input device should provide timely, accurate, and useful data to the main memory of the computer for processing. The following are the most useful input devices.

Keyboard:

This is the standard input device attached to all computers. The layout of the 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. A typical keyboard used in a computer you have to press the 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.

Mouse:

The mouse is an input device that is used with your personal computer. It rolls on a small ball and has two or three buttons on the top. When you roll the mouse across a flat surface the screen censors the mouse in the direction of mouse movement. The cursor moves very fast with mouse giving you more freedom to work in any direction. It is easier and faster to move through a mouse Types of Mouse

• Trackball Mouse: In this, the ball is rolled at one place rolling the mouse on the tabletop.
• Optical Mouse: It uses a light beam to detect movement.
• Wireless Mouse: It is a mouse without a cable. This mouse works up to one and a half meters away from the computer.
• Light Pen Mouse: It uses a light-sensitive detector, requiring you to hold a pen and point it at the screen.
• Joystick Mouse: It usually includes two upright sticks which are moved with the hand and the button is pressed on either stick.

Scanner

The keyboard can input only text through keys provided in it. If we want to input a picture the keyboard cannot do that. The scanner is an optical device that can input any graphical matter and display it back. The common optical scanner devices are:

• Magnetic Ink Character Recognition (MICR): This is widely used by banks to process large volumes of cheques and drafts. Cheques are put inside the MICR. As they enter the reading unit the cheques pass through the magnetic field which causes the read head to recognize the character of the cheques.
• Optical Mark Reader (OMR): This technique is used when students have appeared in objective type tests and they had to mark their answer by darkening a square or circular space by pencil. These answer sheets are directly fed to a computer for grading where OMR is used.
• Optical Character Recognition (OCR): This technique unites the direct reading of any printed character. Suppose you have a set of handwritten characters on a piece of paper. You put it inside the scanner of the computer. This pattern is compared with a site of patterns stored inside the computer. Whichever pattern is matched is called a character read. Patterns that cannot be identified are rejected. OCRs are expensive though better the MICR.
• Barcode Reader (BCR): A barcode reader is an electronic device for reading printed barcodes. Like a flatbed scanner, it consists of a light source, a lens and a light sensor translating optical impulses into electrical ones. Additionally, nearly all barcode readers contain decoder circuitry analyzing the barcode’s image data provided by the sensor and sending the barcode’s content to the scanner’s output port.