CH06_InputOutput

CH06_InputOutput - Chapter 6: Input and Output: Between...

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Chapter 6: Input and Output: Between Analog and Digital Worlds Goal Somehow, bits have to reach the processor of the computer to form instructions and data that will prompt the computer to do something. These bits must result from an action external to the computer. Similarly, once the computer finishes a task, the user needs to learn the results of that task. We can think of these processes as communication between the computer and the rest of the world, input and output. The goal of this chapter is to familiarize the student with the main concepts about input and output. Different types of input and output are listed and defined, and guidelines are given to assess their performance, quality, and costs. After learning this material, the reader will be better informed to determine what kinds of input-output hardware are needed, and what options are available. Input Devices Input devices do more than enter data; they also control the computer by interpreting and translating user actions into commands and data that the computer understands. Input devices also receive and respond to messages from the system. Input can be automated, and does not necessarily involve the user at the time the information is collected. For example, GPS (global positioning system) receivers use radio signals as input from satellites and can automatically record the position and path of agricultural machinery. Similarly, a "yield monitor" device installed in a combine harvester can measure and automatically enter the amount of grain produced at each point of a field. Thus, position and yield are together in a computer file that is created in the computer inside the combine. (A combine is a machine used to harvest grains.) People use input devices to enter commands and data into computers. There are several different kinds of devices, each best suited to a particular situation and a particular kind of data. The most common input device is the traditional QWERTY typewriter keyboard, which can enter both commands and data. Some input devices scan data into the computer from forms (optical mark readers) or from printed text (optical recognition systems) or from special symbols (bar code readers). Digital cameras capture images in digital form that can be input into computers, or photographic images can be digitized with a scanner. Voice recognition systems , which enable people to give spoken commands to a computer, use sophisticated software to enable the system to adjust to different accents. Some software even “learns” to recognize the particular way a person speaks, and automatically becomes better and better at interpreting spoken commands. Touch screens are another type of input device that allow the user to interact with the
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6-2 computer by making choices by touching the display on a special monitor that is sensitive to touch. M
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This note was uploaded on 12/28/2010 for the course PLS 21 taught by Professor Lieth during the Spring '08 term at UC Davis.

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CH06_InputOutput - Chapter 6: Input and Output: Between...

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