Multiplexer fundamentals A multiplexer (MUX) performs which input/output role in digital systems?

Difficulty: Easy

Correct Answer: several inputs and one output

Explanation:


Introduction / Context:
Multiplexers are selection devices used to route one of many input signals to a single output line under the control of select inputs. They are essential in data routing, resource sharing, and implementing logic functions by selection rather than explicit gates.


Given Data / Assumptions:

  • Standard MUX behavior is assumed (e.g., 2-to-1, 4-to-1, 8-to-1, 16-to-1).
  • Control lines select exactly one input at a time.
  • Transmission is ideal; ignore analog details and tristate behavior unless specified.


Concept / Approach:

A MUX funnels multiple candidate inputs into a single pathway. The Boolean function implemented equals the sum of selected minterms based on select lines, which is why MUXes can synthesize logic functions with appropriate input wiring.


Step-by-Step Reasoning:

Identify role: choose exactly one source among many.Confirm I/O structure: several inputs → one output.Select lines determine which input reaches the output.


Verification / Alternative check:

Reference typical parts like 74HC157 (quad 2-to-1) or 74HC151 (8-to-1). Their truth tables show one output reflecting one selected input at a time based on select pins and enable control.


Why Other Options Are Wrong:

  • One input to many outputs describes a demultiplexer, not a multiplexer.
  • One input and one output is just a buffer.
  • Several inputs and several outputs could be a crossbar or bus switch, not a simple MUX.
  • Several outputs selected to one input inverts the concept.


Common Pitfalls:

  • Confusing MUX with DEMUX; they are mirrors of each other.
  • Forgetting enable pins that can tristate or disable the output.


Final Answer:

several inputs and one output

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