【正文】 7章 Input 本章要點 ? What is Input? ? Words and Expressions ? How To Do： Printer ? How To Work： Telephone Wiring System ? Grammar Focus：定語從句 ? Text in Chinese：輸入 ? Reading Selection: Making Connections ? 科技英語的寫作特點（ Ⅱ ） ? Practical Writing：簡歷 What is Input? Computers can understand only the binary machine language of 0s and 1s. Input and output devices are virtually translators between the languages of people and the machine. Input refers to data or instructions that are used by a puter. The users provide input whenever they use system or application programs. Input devices are hardware used to provide input to the puter. The most monly used input devices include keyboards, mice (mouse, pl.), scanners, digital cameras, digitizing tablets and voice recognition 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 im