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No.	Name of Devices	Picture	Description
1	Pens		Pen-based systems--including many personal digital assistants and other types of handheld computers--use a "pen" for data input. This pen-like device is sometimes called a stylus. You hold the pen in your hand and write on a special pad or directly on the screen. You can also use the pen as a pointing device, like a mouse, to select commands
2	Touch Screen		Touch screens accept input by allowing the user to place a fingertip directly on the computer screen, usually to make a selection from a menu of choices. Most touch-screen computers use sensors in or near the computer's screen to detect the touch of a finger.
3	Game Controllers		Game controllers generally fall into two broad categories: game pads and joysticks. Joysticks have been around for a long time and can be used with applications other than games. (Some joystick users actually prefer using a joystick rather than a mouse with some business applications.) Joysticks enable the user to "fly" or "drive" through a game, directing a vehicle or character. They are popular in racing and flying games. A variant of the joystick is the racing game controller, which includes an actual steering wheel.
4	Bar code reader		These devices convert a bar code, which is a pattern of printed bars on products, into a code the computer can understand. The bar code reader emits a beam of light--frequently a laser beam--that is reflected by the bar code image. A light-sensitive detector identifies the bar code image by recognizing special bars at both ends of the image. These special bars are different, so the reader can tell whether the bar code has been read right-side up or upside down.
5	Image scanner		The image scanner is useful because it translates printed images into an electronic format that can be stored in a computer's memory. You can then use software to organize or manipulate the electronic image. For example, if you scan a photo, you can use Adobe Photoshop--a graphics program--to increase the contrast or adjust the colors. If you have scanned a text document, you might want to use optical character recognition (OCR) software to translate the image into text that you can edit. When a scanner first creates an image from a page, the image is stored in the computer's memory as a bitmap. A bitmap is a grid of dots, each dot represented by one or more bits. The job of OCR software is to translate that array of dots into text that the computer can interpret as letters and numbers. .
6	Microphones		Now that sound capabilities are standard in computers, microphones are becoming increasingly important as input devices to record speech. Spoken input is used most often in multimedia, where the presentation can benefit from narration. Most PCs now have phone-dialing capabilities, so if you have a microphone and speakers (or a headset microphone with an earphone), you can use your PC to make telephone calls
7	PC Video Input		The video cameras used with computers are similar to those used in production studios. PC video cameras, however, digitize images by breaking them into individual pixels. (A pixel is one or more dots that express a portion of an image. Pixels are discussed in more detail in Unit 3, "Output Devices.") Each pixel's color and other characteristics are stored as digital code. This code is then compressed (video images can be very large) so that it can be stored on disk or transmitted over a network.
8	Digital Camera		Most digital cameras can store dozens of high-resolution images at a time, and most cameras accept additional memory that increases their capacity even further. Moving digital images from a digital camera to a computer is a simple process, using standard cables, disks, or even infrared networking capabilities. A wide range of digital cameras is available, from inexpensive home-use models (with prices starting at just over $100) to professional versions costing several thousand dollars.