Cascading decade counters Four cascaded modulus-10 (decade) counters together will produce what overall modulus?
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A10
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B100
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C1,000
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D10,000
Answer
Correct Answer: 10,000
Explanation
Introduction / Context:Counters are often cascaded to extend the range of counting. When you cascade counters, the total modulus is the product of the individual moduli, enabling decimal timekeeping and event-counting over large ranges using standard decade devices.
Given Data / Assumptions:
- Each stage: modulus 10.
- Number of stages: 4 (units, tens, hundreds, thousands).
- Proper cascading: carry (or ripple) from one stage clocks the next.
Concept / Approach:The overall modulus of cascaded counters equals the product of their individual moduli. Therefore, four decades produce 10 * 10 * 10 * 10 = 10,000 unique states before the sequence repeats. This principle generalizes to any set of cascaded counters with possibly different moduli (overall modulus = product of all).
Step-by-Step Solution:
Identify per-stage modulus M = 10.Compute product: 10^4 = 10,000.Interpretation: counter counts 0000–9999 (ten thousand states).Reset after 9999 back to 0000 completes the cycle.Verification / Alternative check:Observe a 4-digit decimal counter: units advances each pulse; tens advances each time units rolls over; and so on—clearly yielding 10,000 states.
Why Other Options Are Wrong:
- 10, 100, 1,000: These are products for 1, 2, and 3 cascaded decades respectively.
Common Pitfalls:Miscounting the number of stages; failing to ensure proper carry/ripple connections so that the theoretical modulus is actually realized in hardware.
Final Answer:10,000