Multiplexing means transmitting a large number of information units over a smaller number of channels or lines. It's a digital circuit with multiple signal inputs, one of which is selected by separate address inputs to be sent to the single output. Simply it’s a data selector. It's not easy to describe without the logic diagram, but is easy to understand when the diagram is available.

In this lab we use 2-to-1 multiplexer, X is the selection line, A and B are the two input lines. When X is equal to 0, B is selected and so the data stored in A is transmitted to the output. When X is equal to 1, A is selected and the data stored in B is transmitted to the output as shown in the truth table below:

  The Experiment

In the applet below change in the choice box to see the result for different combinations.