Digital Electronics
Explainer
Multiplexers: One Output, Many Inputs
How does a CPU pick one signal out of eight using just three wires?
Quick check · tap an answer to continue
Lesson notes
Key points
- A multiplexer, or MUX, is a combinational circuit that routes one of several data inputs to a single output.
- Select lines carry a binary number, so n select lines can choose between two to the power n inputs.
- For a two-to-one MUX, the output equals S-bar times I-zero plus S times I-one, built from AND and OR gates.
- When S is zero, I-zero reaches the output; when S is one, I-one reaches it instead.
Definitions
- Multiplexer (MUX)
- Combinational circuit that selects one of 2ⁿ data inputs and passes it to one output, using n select lines
Takeaway: n select lines let a MUX choose one of 2ⁿ inputs.
Quick check: How many select lines does a 16-to-1 MUX need?
- 16
- 4
- 8
MultiplexerSelect lines2:1 MUXSelection
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