数字设计原理与实践（九）.

数字设计原理与实践（九）.
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9
c h a p t e r




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Sequential-Circuit
Design Examples

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ust about every real digital system is a sequential circuit―all it takes


J is one feedback loop, latch, or flip-flop to make a circuit’s present
behavior depend on its past inputs. However, if we were to design or
analyze a typical digital system as a single sequential circuit, we


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would end up with an enormous state table. For example, strictly speaking, a
PC with only 16 Mbytes of main memory is a sequential circuit with well
over 2128,000,000 states!