Digital design — encoder fundamentals: in combinational logic, is it accurate that an encoder circuit is specifically designed to generate a coded output (e.g., binary or BCD) corresponding to which single input line is active?

Introduction / Context:
An encoder is a standard combinational logic block used in digital systems to compress multiple input lines into a smaller number of output bits. Typical examples include 8-to-3 binary encoders and keyboard encoders. This question checks the core definition: does an encoder generate a specific code on its outputs based on which input line is asserted?

Given Data / Assumptions:

• One-hot or priority-encoded inputs are considered.
• Exactly one valid input is active at a time unless a priority encoder is used.
• Outputs are binary-coded representations (binary/BCD etc.).

Concept / Approach:
An N-to-m encoder maps N input lines to m outputs, where m = ceil(log2 N). The function is the inverse of a decoder: instead of expanding a coded input into one-of-N outputs, an encoder compresses one-of-N inputs into a code. Priority encoders add logic to resolve multiple simultaneous inputs according to a defined priority, ensuring a valid coded result.

Step-by-Step Solution:

Verification / Alternative check:
Truth tables for standard 4-to-2 or 8-to-3 encoders show unique coded outputs for each asserted input line. Priority encoder datasheets confirm the same with added priority/valid flags.

Why Other Options Are Wrong:
Does not apply: contradicts the device definition.
Only for parity encoders: parity generation is a different function (error checking), not line-to-code encoding.
Applies only when all inputs are active: encoders assume one active input; all-active yields invalid unless priority or masking is used.

Common Pitfalls:
Confusing encoders with decoders or multiplexers; ignoring the need for priority when simultaneous inputs can occur.

Final Answer:
Applies