be constructed by using smaller multiplexers by chaining them together. For example, an 8-to-1 multiplexer can be made with two 4-to-1 and one 2-to-1 multiplexers. The two 4-to-1 multiplexer outputs are fed into the 2-to-1 with the selector pins on the 4-to-1's put in parallel giving a total number of selector inputs to 3, which is equivalent to an 8-to-1. List of ICs which provide multiplexing For 7400 series part numbers in the following table, "x" is the logic family. Digital demultiplexers Demultiplexers take one data input and a number of selection inputs, and they have several outputs. They forward the data input to one of the outputs depending on the values of the selection inputs. Demultiplexers are sometimes convenient for designing general-purpose logic because if the demultiplexer's input is always true, the demultiplexer acts as a binary decoder. This means that any function of the selection bits can be constructed by logically OR-ing the correct set of outputs. If X is the input and S is the selector, and A and B are the outputs: List of ICs which provide demultiplexing For 7400 series part numbers in the following table, "x" is the logic family. Multiplexers as PLDs Multiplexers can also be used as programmable logic devices, to implement Boolean functions. Any Boolean function of n variables and one result can be implemented with a multiplexer with n selector inputs. The variables are connected to the selector inputs, and the function result, 0 or 1, for each possible combination of selector inputs is connected to the corresponding data input. If one of the variables (for example, D) is also available inverted, a multiplexer with n-1 selector inputs is sufficient; the data inputs are connected to 0, 1, D, or ~D, according to the desired output for each combination of the selector inputs. See also Digital subscriber line access multiplexer (DSLAM) Inverse multiplexer Multiplexing Code-division multiplexing Frequency-division multiplexing Time-division multiplexing Wavelength-division multiplexing Statistical multiplexing Charlieplexing Priority encoder Rule 184, a cellular automaton in which each cell acts as a multiplexer for the values from the two adjacent cells Statistical multiplexer References Further reading External links Multiplexing Digital circuits