电气专业（毕业设计）中英文对照翻译.doc

河南理工大学毕业设计外文翻译 PAGE \* MERGEFORMAT PAGE \* MERGEFORMAT 1 Chapter 3 Digital Electronics 3.1 Introduction A circuit that employs a numerical signal in its operation is classified as a digital circuit.Computers,pocket calculators, digital instruments, and numerical control (NC) equipment are common applications of digital circuits. Practically unlimited quantities of digital information can be processed in short periods of time electronically. With operational speed of prime importance in electronics today,digital circuits are used more frequently. In this chapter, digital circuit applications are discussed.There are many types of digital circuits that have applications in electronics, including logic circuits, flip-flop circuits, counting circuits, and many others. The first sections of this unit discuss the number systems that are basic to digital circuit understanding. The remainder of the chapter introduces some of the types of digital circuits and explains Boolean algebra as it is applied to logic circuits. 3.2 Digital Number Systems The most common number system used today is the decimal system,in which 10 digits are used for counting. The number of digits in the system is called its base (or radix).The decimal system，therefore，has a base of 10. Numbering systems have a place value，which refers to the placement of a digit with respect to others in the counting process. The largest digit that can be used in a specific place or location is determined by the base of the system. In the decimal system the first position to the left of the decimal point is called the units place. Any digit from 0 to 9 can be used in this place.When number values greater than 9 are used,they must be expressed with two or more places.The next position to the left of the units place in a decimal system is the tens place.The number 99 is the largest digital value that can be expressed by two places in the decimal system.Each place added to the left extends the number system by