Understanding a multiplexed display interface A “multiplexed display” being driven by a logic circuit typically behaves like which of the following digital functions?
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Aaccepts data inputs from one line and passes this data to multiple output lines
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Baccepts data inputs from several lines and allows one of them at a time to pass to the output
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Caccepts data inputs from multiple lines and passes this data to multiple output lines
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Daccepts data inputs from several lines and multiplexes this input data to four BCD lines
Answer
Correct Answer: accepts data inputs from several lines and allows one of them at a time to pass to the output
Explanation
Introduction / Context:In digital electronics, the word “multiplexed” often refers to the technique of selecting one of many inputs to drive a shared output resource for a short time slice. This is central to display scanning, where multiple digit modules share segment lines and are enabled one at a time in rapid succession.
Given Data / Assumptions:
- A logic circuit time-shares resources among several display elements (digits).
- Only one source is selected to drive the common output bus at any instant.
- Human persistence of vision makes sequential updates appear simultaneous.
Concept / Approach:The fundamental digital component that models this selection is the multiplexer (data selector). A multiplexer accepts many data inputs and, under control of select lines, routes exactly one input to the output. In displays, digit-select lines and segment busses implement the same concept at the system level.
Step-by-Step Solution:
Identify device behavior: multiple inputs → one chosen output at a time.Map to definition: a multiplexer allows one of several inputs to pass to the output.Relate to displays: the controller selects each digit in turn, applying its data to shared segment lines.Conclude that option (b) matches the multiplexed function.Verification / Alternative check:Contrast with a demultiplexer (one input to many outputs), which is not the typical function implied by “multiplexed display” selection of input data.
Why Other Options Are Wrong:
- (a) describes a demultiplexer, not a multiplexer.
- (c) is a broadcast or bus-driver scenario, not selected routing.
- (d) is overly specific and not a generic definition.
Common Pitfalls:Confusing the system-level display scanning (digit enabling) with the data-selection concept; both occur, but the term “multiplexed” aligns with selecting one of many inputs at a time.
Final Answer:accepts data inputs from several lines and allows one of them at a time to pass to the output