Decade counters and BCD counters: Evaluate the claim “All decade counters are BCD counters.” Choose whether this statement is accurate in digital electronics, where a decade counter has 10 distinct states and a Binary-Coded Decimal (BCD) counter specifically represents decimal digits in 8421 code.

Introduction / Context:
Decade counters and Binary-Coded Decimal (BCD) counters are related but not identical categories in digital electronics. A decade counter is any counter that sequences through ten distinct states before recycling, while a BCD counter is a specific decade counter that outputs the 8421 binary pattern for decimal digits 0 through 9. This question tests whether every decade counter must necessarily be a BCD counter.

Given Data / Assumptions:

• A decade counter has 10 states per cycle.
• A BCD counter presents outputs corresponding to 0000 through 1001 (for 0–9) in 8421 coding.
• Other decade counters may use non-BCD state assignments (e.g., Johnson or ring-based sequences of length 10).

Concept / Approach:
All BCD counters are decade counters, but the reverse need not hold. A decade counter is defined by its modulus (10), whereas a BCD counter is defined by both modulus and the specific state encoding used (8421 for the 10 valid decimal digits). Non-BCD decade counters still count ten states but do not map their outputs to the standard BCD digit patterns.

Step-by-Step Solution:

Verification / Alternative check:
Inspect example datasheets/circuits: some decade counters specify “BCD outputs,” others specify “10-state sequence” without guaranteeing 8421 coding.

Why Other Options Are Wrong:
“Correct” conflates modulus with encoding. “True only for synchronous counters” and “True only for ripple counters” are irrelevant qualifiers; clocking style does not force BCD encoding.

Common Pitfalls:
Assuming “decade” implies BCD coding. In reality, decade only guarantees 10 states, not how those states are represented.

Final Answer:
Incorrect