第7章 Input,本章要点 What is Input? Words and Expressions How To Do：Printer How To Work：Telephone Wiring System Grammar Focus：定语从句 Text in Chinese：输入 Reading Selection: Making Connections 科技英语的写作特点（） Practical Writing：简历,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 computer. The users provide input whenever they use system or application programs. Input devices are hardware used to provide input to the computer. The most commonly 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 computers 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 computer (See Figure 7-1-1). 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 7-1-2). Pointing input devices provide a comfortable interface between the users and the computer system unit. There are kinds of pointing devices including the mouse, the joystick (See Figure 7-2), the touch screen (See Figure 7-3), and the light pen.,What is Input?,* A mouse can have two or more buttons used to select command 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 7-4-1). 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 7-4-2). It can be used on any surface. The wireless mouse is a battery-powered device that uses radio waves or infrared light waves to communicate with the system unit(See Figure 7-4-3).,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 7-5-1). * Bar code readers are mostly used in supermarkets to read product representing bar codes on product containers and input the information to the computer, which has stored the latest prices for the products, to tell the electronic cash register the price of every product (See Figure 7-5-2). 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 magnetic 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 cameras memory rather than on film (See Figure 7-6-1). 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 cameras memory(See Figure 7-6-2). Webcams are specialized digital video cameras that capture images and send them to a computer through the Internet and they are used to broadcast weather and traffics (See Figure 7-7). Figure 7-5-1 Figure 7-5-2 Figure 7-6-1 Figure 7-6-2Figure 7-8Figure 7-7 Audio-input devices convert sounds into a form that can be processed by a computer. The most widely used audio-input device is the microphone(See Figure 7-8)A microphone, a sound card and special software make up a voice recognition system. The voice recognition system allows users to operate the computer and to create documents by using voice commands.,What is Input?,Notes: 1“Keyboards convert numbers, letters and special characters that people understand into electrical signals that are sent to and processed by the system unit.” 本句中，“convert into”意为：将转化为；两个“that”引导定语从句分别修饰“special characters”和“electrical signals”。 本句意为：键盘将人能够理解的数字、字母和特殊符号转化为计算机系统能够发送和处理的信号。 2“A mouse can have two or more buttons used to select command options and to control information presented on the monitor.” 本句中，“used toon the monitor”为过去分词短语作后置定语修饰buttons，其中“to select command options