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  • Question
  • How many flip-flops are required to construct a decade counter?


  • Options
  • A. 10
  • B. 8
  • C. 5
  • D. 4

  • Correct Answer



  • Counters problems


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    • 1. List which pins need to be connected together on a 7492 to make a MOD-12 counter.

    • Options
    • A. 1 to 12, 11 to 6, 9 to 7
    • B. 1 to 12, 12 to 6, 11 to 7
    • C. 1 to 12, 9 to 6, 8 to 7
    • D. 1 to 12
    • Discuss
    • 2. A 4-bit ripple counter consists of flip-flops, which each have a propagation delay from clock to Q output of 15 ns. For the counter to recycle from 1111 to 0000, it takes a total of ________.

    • Options
    • A. 15 ns
    • B. 30 ns
    • C. 45 ns
    • D. 60 ns
    • Discuss
    • 3. When two counters are cascaded, the overall MOD number is equal to the ________ of their individual MOD numbers.

    • Options
    • A. product
    • B. sum
    • C. log
    • D. reciprocal
    • Discuss
    • 4. One of the major drawbacks to the use of asynchronous counters is:

    • Options
    • A. low-frequency applications are limited because of internal propagation delays
    • B. high-frequency applications are limited because of internal propagation delays
    • C. asynchronous counters do not have major drawbacks and are suitable for use in high- and low-frequency counting applications
    • D. asynchronous counters do not have propagation delays and this limits their use in high-frequency applications
    • Discuss
    • 5. For a one-shot application, how can HDL code be used to make a circuit respond once to each positive transition on its trigger input?

    • Options
    • A. By using a counter
    • B. By using an active clock
    • C. By using an immediate reload
    • D. By using edge trapping
    • Discuss
    • 6. The circuit given below fails to produce data output. The individual flip-flops are checked with a logic probe and pulser, and each checks OK. What could be causing the problem?


    • Options
    • A. The data output line may be grounded.
    • B. One of the clock input lines may be open.
    • C. One of the interconnect lines between two stages may have a solder bridge to ground.
    • D. One of the flip-flops may have a solder bridge between its input and Vcc.
    • Discuss
    • 7. The process of designing a synchronous counter that will count in a nonbinary manner is primarily based on:

    • Options
    • A. external logic circuits that decode the various states of the counter to apply the correct logic levels to the J-K inputs
    • B. modifying BCD counters to change states on every second input clock pulse
    • C. modifying asynchronous counters to change states on every second input clock pulse
    • D. elimination of the counter stages and the addition of combinational logic circuits to produce the desired counts
    • Discuss
    • 8. In a VHDL retriggerable edge-triggered one-shot, which condition will not exist when a clock edge occurs?

    • Options
    • A. A trigger edge has occurred and we must load the counter.
    • B. The counter is zero and we need to keep it at zero.
    • C. The shift register is reset.
    • D. The counter is not zero and we need to count down by one.
    • Discuss
    • 9. To operate correctly, starting a ring counter requires:

    • Options
    • A. clearing one flip-flop and presetting all the others.
    • B. clearing all the flip-flops.
    • C. presetting one flip-flop and clearing all the others.
    • D. presetting all the flip-flops.
    • Discuss
    • 10. What type of register is shown below?


    • Options
    • A. Parallel in/parallel out register
    • B. Serial in/parallel out register
    • C. Serial/parallel-in parallel-out register
    • D. Parallel-access shift register
    • Discuss


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