In digital electronics, which specific logic circuit is used to convert a BCD (binary-coded decimal) input into an equivalent decimal (0–9) output for display or selection purposes?

Introduction / Context:
A common task in digital systems is to take a 4-bit BCD input (0000 to 1001 representing 0–9) and produce a one-of-ten output that can directly drive indicators or select one of several circuits. The device dedicated to this mapping is a BCD-to-decimal decoder (often called a 1-of-10 decoder).

Given Data / Assumptions:

• Input domain: valid BCD codes (0000–1001).
• Output domain: ten mutually exclusive lines (D0–D9), one active at a time.
• Invalid BCD codes (1010–1111) are either ignored or treated as don’t-cares depending on the design.

Concept / Approach:
A decoder converts coded inputs into a set of outputs in which exactly one line (or a defined pattern) represents each input code. BCD-to-decimal decoders, such as classic TTL/CMOS parts, assert exactly one of ten outputs corresponding to the decimal value of the BCD input. This is distinct from encoders, multiplexers, or generic “code converters.”

Step-by-Step Solution:

Verification / Alternative check:
Standard logic catalogs list BCD-to-decimal decoders used to drive ten lamps, relays, or display segments (through drivers), validating the choice.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing decoders and demultiplexers (they are related but serve different immediate purposes). Also, forgetting to handle invalid BCD inputs can cause unintended outputs.

Final Answer:
decoder