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Digital Electronics: Principles, Devices and Applications

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Counters <strong>and</strong> Registers 467(9)CLK C1/SRG8(13)QHBA(11)(12)&1D(14)QH(a)CLRCLK(9)(8)RC1/SRG8AB(1)(2)&1D(3)(4)(5)(6)(10)(11)(12)(13)Q AQ BQ CQ DQ EQ FQ GQ H(b)Figure 11.53 IEEE/ANSI notation for (a) IC 7491 <strong>and</strong> (b) IC 74164.3. Briefly describe:(a) how the architecture of an asynchronous UP counter differs from that of a DOWN counter;(b) how the architecture of a ring counter differs from that of a shift counter.4. Briefly explain why the maximum usable clock frequency of a ripple counter decreases as moreflip-flops are added to the counter to increase its MOD-number.5. Why is the maximum usable clock frequency in the case of a synchronous counter independent ofthe size of counter?6. How can presettable counters be used to construct counters with variable modulus?

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