Multiplexers (Data Selectors)

• IC 74157
• A multiplexer (MUX) is a device that allows digital information from several sources to be routed onto a single line for transmission over that line to a common destination.
  • The basic multiplexer has several data-input lines and a single output line.
  • It also has data-select inputs, which permit digital data on any one of the inputs to be switched to the output line.
    
• A 2-bit code on the data-select ($S$) inputs will allow the data on the selected data input to pass through to the data output.
  • If a binary 0 ($S_1=0$ and $S_0=0$) is applied to the data-select lines, the data on input $D_0$ appear on the data-output line.
  • If a binary 1 ($S_1=0$ and $S_0=1$) is applied to the data-select lines, the data on input $D_1$ appear on the data output.
  • If a binary 2 ($S_1=1$ and $S_0=0$) is applied, the data on $D_2$ appear on the output.
  • If a binary 3 ($S_1=1$ and $S_0=1$) is applied, the data on $D_3$ are switched to the output line.