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## Input Devices ### Touch-sensitive screens Touch-sensitive screens let you interact with the computer by touching the screen. The pointing device in this instance is your finger. There are three types of touchscreen: * **Pressure sensitive:** The screen consists of two layers with a gap in bet...

## Input Devices ### Touch-sensitive screens Touch-sensitive screens let you interact with the computer by touching the screen. The pointing device in this instance is your finger. There are three types of touchscreen: * **Pressure sensitive:** The screen consists of two layers with a gap in between. When you touch the screen, the two layers come into contact and the electrical flow that follows lets the sensors determine the touch point. * **Capacitive surface:** The screen consists of a glass panel covered with an electrode layer. When you touch the screen, some of the electrical charge moves from the screen to your finger, and the sensors use this drop in electrical charge to determine the touch point. * **Light beam:** The surface of the screen is covered with a grid of invisible infrared light beams. When you touch the screen, you disturb the light beams and the sensors use this disturbance to determine the touch point. For example, capacitive surface or light beam touchscreens are the types mainly used in bank ATM machines. These touchscreens allow you to perform actions on your bank account by following instructions and options on-screen, using your finger to choose the option you wish. ### Light Pens A light pen is shaped like a pen and is connected to a VDU or monitor. It allows you to point and make selections more accurately on a screen. The tip of the light pen contains a light-sensitive element that, when placed against the screen, detects the light from the screen and enables the computer to identify the location of the pen. Making selections with a light pen on a touch-sensitive screen is far more accurate than using your finger. Light pens also allow the user to draw directly onto the screen. However, they are not as accurate as a digitising tablet and drawing can become uncomfortable. ### Scanning devices The different types of scanning devices include the following: * Scanners * Magnetic ink character recognition (MICR) readers * Optical mark readers (OMRs) * Optical character recognition (OCR) readers * Barcode readers * Magnetic strip codes.