Terminology — asynchronous counters are often called what? Fill in the blank: Asynchronous counters are often called ________ counters because clock transitions ripple through the stages.

Introduction / Context:
Digital vocabulary matters. Multiple names for the same concept can hinder learning if their equivalence is not recognized. This question checks the common synonym for asynchronous counters used in textbooks and datasheets.

Given Data / Assumptions:

• An asynchronous counter clocks its first stage from the external source; subsequent stages are clocked by upstream outputs.
• Clock information propagates, or “ripples,” through the chain.
• Non-zero propagation delay exists for each stage.

Concept / Approach:
The term “ripple counter” vividly describes the sequential toggling of stages caused by cascaded clocking. Because these toggles occur slightly later at each stage, the apparent clock edge ripples along the register, hence the name. Thus, “asynchronous counter” and “ripple counter” are interchangeable labels for the same structure.

Step-by-Step Solution:

Verification / Alternative check:
Vendor datasheets and logic family guides (e.g., 74HC/74LS) explicitly label parts as “ripple-carry binary counters,” reinforcing the synonymy.

Why Other Options Are Wrong:

• toggle: Describes a flip-flop action, not a counter class.
• binary: Many counters are binary, including synchronous ones; not distinctive.
• flip-flop: A building block, not the counter type.
• Johnson: A different counter topology (twisted ring), not synonymous with asynchronous.

Common Pitfalls:
Assuming “ripple” is a special mode rather than the core asynchronous mechanism; conflating counter base (binary/decimal) with clocking strategy.

Final Answer:
ripple