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598 Chapter 8 Sequential Logic Design PracticesDO8.4.3NOTMSI Counters and ApplicationsCOPY74x163The most popular MSI counter is the 74x163, a synchronous 4-bit binary counterwith active-low load and clear inputs, with the traditional logic symbol shown inFigure 8-30. Its function is summarized by the state table in Table 8-11, and itsDOinternalNOTlogic diagram is shown in FigureCOPY8-31.74x163The ’163 uses D flip-flops rather than T flip-flops internally to facilitate the2CLKload and clear functions. Each D input is driven by a 2-input multiplexer consistingof an OR gate and two AND gates. The multiplexer output is 0 if the CLR_L1CLR9LDinput is asserted. Otherwise, the top AND gate passes the data input (A, B, C,7DOENPor D)NOTto the output if LD_L is asserted.COPYIf neither CLR_L nor LD_L is asserted, the10ENT314 bottom AND gate passes the output of an XNOR gate to the multiplexer output.A QA413B QB512 Table 8-11 State table for a 74x163 4-bit binary counter.C QC611DOD QDNOTInputs CurrentCOPY15State Next StateRCOCLR_L LD_L ENT ENP QD QC QB QA QD∗ QC∗ QB∗ QA∗Figure 8-30Traditional logic 0 x x x x x x x 0 0 0 0symbol forDO1NOT0 x x x xCOPYx x D C B Athe 74x163.1 1 0 x x x x x QD QC QB QA1 1 x 0 x x x x QD QC QB QA1 1 1 1 0 0 0 0 0 0 0 1DO NOT1 1 1 1 0 0COPY0 1 0 0 1 01 1 1 1 0 0 1 0 0 0 1 11 1 1 1 0 0 1 1 0 1 0 01 1 1 1 0 1 0 0 0 1 0 1DO NOT1 1 1 1 0 1COPY0 1 0 1 1 01 1 1 1 0 1 1 0 0 1 1 11 1 1 1 0 1 1 1 1 0 0 01 1 1 1 1 0 0 0 1 0 0 1DO NOT COPY1 1 1 1 1 0 0 1 1 0 1 01 1 1 1 1 0 1 0 1 0 1 11 1 1 1 1 0 1 1 1 1 0 01 1 1 1 1 1 0 0 1 1 0 1DO NOT COPY1 1 1 1 1 1 0 1 1 1 1 01 1 1 1 1 1 1 0 1 1 1 11 1 1 1 1 1 1 1 0 0 0 0Copyright © 1999 by John F. WakerlyCopying Prohibited
Section 8.4 Counters 599DO NOT COPY(2)CLK(9)LD_LDO NOT COPY(1)CLR_L(3)A(14)D QQADO NOT COPYCK QDO(4)NOT COPYB(13)D QQBCK QDO NOT COPY(5)C(12)D QQCCK QDO NOT COPY(6)D(11)D QQDDO NOT COPYCK QDO NOT COPY(15)RCO(7)ENPDO(10)ENTNOT COPYFigure 8-31 Logic diagram for the 74x163 synchronous 4-bit binary counter,including pin numbers for a standard 16-pin dual in-line package.Copyright © 1999 by John F. WakerlyCopying Prohibited
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Page 47 and 48: Section 8.4 Counters 607DO NOT COPY
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Section *8.6 Iterative versus Seque
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Section *8.6 Iterative versus Seque
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Section 8.7 Synchronous Design Meth
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Section 8.8 Impediments to Synchron
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References 687DOAs we mentioned in
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Exercises 689DO NOT COPY74x1692CLOC
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Exercises 691DO NOT COPYZ is assert
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Exercises 6938.54DOModify the ABEL
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Exercises 695DO NOT COPYSYNCINASYNC
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