Decoder fundamentals: does the general function of a decoder involve asserting one or more specific outputs when its input lines match a particular digital state (code)?

Introduction / Context:
Decoders are the counterpart to encoders: they expand a compact code into one-of-N (or sometimes multiple) outputs. They are used in address decoding, display driving, and memory chip selection. The question checks the canonical role of decoders in activating outputs when an input code is recognized.

Given Data / Assumptions:

• K input lines represent a binary code.
• Up to 2^K distinct outputs are possible (or grouped outputs).
• Active-high or active-low conventions may apply.

Concept / Approach:
A decoder generates minterms of the inputs and asserts the output(s) corresponding to the input pattern. Examples include the 3-to-8 decoder (one of eight outputs goes active) and 4-to-16 address decoders. Some variants include enable inputs and multiple active outputs for special coding schemes, but the essence remains detection and activation based on input states.

Step-by-Step Solution:

Verification / Alternative check:
Standard truth tables (e.g., 74HC138) show exactly one active output for each 3-bit input when enabled, confirming the definition.

Why Other Options Are Wrong:
Does not apply: contradicts core functionality.
Active-low only / all-ones-only: output polarity and specific codes are implementation details; the function is general detection and activation.

Common Pitfalls:
Confusing decoders with demultiplexers; overlooking enable and polarity conventions.

Final Answer:
Applies