In encoder design, when two or more inputs become active at the same time, what is the process used to determine which input takes precedence?

Introduction / Context:
Encoders convert many input lines into a compact binary representation. In real systems, more than one input may assert simultaneously (e.g., multiple keys pressed). Priority handling is crucial to ensure deterministic output without ambiguity, which is why priority encoders are a standard logic block.

Given Data / Assumptions:

• Multiple input lines may be active concurrently.
• The encoder must output one binary code.
• A defined precedence rule is required.

Concept / Approach:
A priority encoder assigns an ordering to inputs (e.g., highest-numbered input wins). When several inputs are asserted, the encoder outputs the code corresponding to the highest-priority input and may provide a valid/enable flag. This avoids metastability or ambiguous codes that a simple encoder might produce.

Step-by-Step Solution:
Define priority: I7 > I6 > ... > I0.If I3 and I6 are high, encoder outputs the code for I6.Output may include a group signal (GS) or enable output (EO) to cascade devices.Thus, the correct process is priority encoding.

Verification / Alternative check:
ICs such as 74HC148 (8-to-3 priority encoder) implement specified priority rules and demonstrate predictable outputs in multi-assert conditions.

Why Other Options Are Wrong:

• FIFO: A buffering/queuing concept, not instantaneous priority resolution.
• Ripple blanking: Used in display chains to suppress leading zeros, unrelated to encoders.
• Priority decoding: Not the conventional term; decoding is the inverse function.
• TDM: A multiplexing method over time, not a logic priority scheme.

Common Pitfalls:

• Using a simple encoder where a priority encoder is required can lead to undefined outputs.
• Forgetting to handle the no-input-active case with a valid flag or default code.

Final Answer:
priority encoding