Name the device: Which MSI component generates a compact binary code at its outputs corresponding to the index of a single active numeric input line (one-hot input → coded output)?

Introduction / Context:
Digital systems frequently need to compress one-of-many signals into a compact binary representation. This occurs in keypad scanners, interrupt controllers, and sensor arrays. Identifying the right MSI device ensures correct design and pin budgeting.

Given Data / Assumptions:

• One input line at a time is active.
• The device outputs a binary word indicating which line is active.
• No arithmetic comparison or data selection among many sources to a single sink is implied.

Concept / Approach:
By definition, an encoder maps a one-hot or one-of-M input to an N-bit binary output. A decoder performs the reverse; a multiplexer selects one data input to drive an output; a comparator evaluates relationships between two binary words. Therefore, the correct device is an encoder.

Step-by-Step Solution:
Recognize mapping: one-hot input → compact code.Match with MSI definitions → encoder.Exclude other devices (decoder inverse, multiplexer selector, comparator relational logic).Conclude: the device is an encoder.

Verification / Alternative check:
Parts like 74148 (8-to-3) and 74HC147 implement this behavior directly, sometimes with priority to resolve multiple active inputs.

Why Other Options Are Wrong:
Decoder expands a code to one-hot. Multiplexer routes data rather than produces a code. Comparator outputs relation flags (less, equal, greater), not a binary index.

Common Pitfalls:
Assuming any single-output device is a comparator; forgetting the encoder/decoder directionality.

Final Answer:
an encoder