計(jì)算機(jī)專業(yè)英語第7章-wenkub
2022-10-28 16:18:37 本頁面
【正文】 ecognition devices. Input devices translate numbers, letters, and actions that people understand into symbols that puters can process. * Keyboards convert numbers, letters and special characters that people understand into electrical signals that are sent to and processed by the system unit of the puter (See Figure 711). There are a wide variety of keyboard designs. They range from the traditional keyboards to the ergonomic keyboards to the space saving folding keyboards (See Figure 712). Pointing input devices provide a fortable interface between the users and the puter system unit. There are kinds of pointing devices including the mouse, the joystick (See Figure 72), the touch screen (See Figure 73), and the light pen. What is Input? * A mouse can have two or more buttons used to select mand options and to control information presented on the monitor. There are three basic designs of mouse types: mechanical mouse, optical mouse, and wireless mouse. The mechanical mouse is the traditional type and the most widely used (See Figure 741). The mechanical mouse is attached with a cord to the system unit and as you move the mouse across a smooth surface, the roller on the bottom controls the pointer on the screen, and you use the left button and the right button to select items. Some even have a wheel button to scroll through information presented on the screen. The optical mouse has no roller and it emits and senses light to detect the mouse movement (See Figure 742). It can be used on any surface. The wireless mouse is a batterypowered device that uses radio waves or infrared light waves to municate with the system unit(See Figure 743). What is Input? Scanners read documents and graphic images and photographs and then convert them into a form that the system unit can process. There are three types of scanning devices: optical scanners, bar code readers and character and mark recognition devices. Optical scanners copy texts and images together with their colors (See Figure 751). * Bar code readers are mostly used in supermarkets to read product representing bar codes on product containers and input the information to the puter, which has stored the latest prices for the products, to tell the electronic cash register the price of every product (See Figure 752). Character and mark recognition devices are able to recognize special characters and marks. They are specialty devices for certain applications, for instance, in banks to read characters made of ink containing magic particles. What is Input? Image capturing devices create or capture original images. These devices include digital cameras and digital video cameras. * Digital cameras are different from traditional cameras in that images are recorded digitally on a disk or in the camera′s memory rather than on film (See Figure 761). You can take a picture, view it immediately and even place it on your own Web page. Digital video cameras record motion digitally on a disk or in the camera′s memory(See Figure 762). Webcams are specialized digital video cameras that capture images and send them to a puter through the Inter and they are used to broadcast weather and traffics (See Figure 77). Figure 751 Figure 752 Figure 761 Figure 762Figure 78Figure 77 Audioinput devices convert sounds into a form that can be processed by a puter. The most widely used audioinput device is the microphone(See Figure 78)． A microphone, a sound card and special software make up a voice recognition system. The voice recognition system allows users to operate the puter and to create documents by using voice mands. What
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