Dale - Computer Science Illuminated 81

Dale - Computer Science Illuminated 81 - number system,...

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Digitize The act of breaking information down into discrete pieces 54 Chapter 3 Data Representation 73 ° 75 ° 74 ° 76 ° 77 ° 78 ° Figure 3.1 A mercury thermometer continually rises in direct proportion to the tempera- ture Fahrenheit, and the mercury is accurately indicating that, even if our markings are not fine enough to note such small changes. See Figure 3.1. Analog information is directly proportional to the continuous, infinite world around us. Computers, therefore, cannot work well with analog information. So instead, we digitize information by breaking it into pieces and representing those pieces separately. Each of the representations we discuss in this chapter has found an appropriate way to take a continuous entity and separate it into discrete elements. Those discrete elements are then individually represented using binary digits. But why do we use binary? We know from Chapter 2 that binary is just one of many equivalent number systems. Couldn’t we use, say, the decimal
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Unformatted text preview: number system, with which we are already more familiar? We could. In fact, its been done. Computers have been built that are based on other number systems. However, modern computers are designed to use and manage binary values because the devices that store and manage the data are far less expensive and far more reliable if they only have to represent one of two possible values. Also, electronic signals are far easier to maintain if they transfer only binary data. An analog signal continually fluctuates in voltage up and down. But a digital signal has only a high or low state, corresponding to the two binary digits. See Figure 3.2. All electronic signals (both analog and digital) degrade as they move down a line. That is, the voltage of the signal fluctuates due to environ-mental effects. The trouble is that as soon as an analog signal degrades,...
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