:PROPERTIES: :ID: 39a06559-ef08-4a8a-834c-961e66ea8b54 :mtime: 20231013031815 :ctime: 20231013031643 :ROAM_ALIASES: selector :END: #+title: multiplexer #+filetags: :public:project: * Definition A *multiplexer*, also called a *mux*, also called a *selector*, is a type of digital circuit which chooses 1 out of many inputs to steer its single output. For example, a 2-to-1 multiplexer takes in $x,y,z$ If $y = 1$, the multiplexer returns $x$, and if $y = 0$, the multiplexer returns $z$. * How to draw a multiplexer In a circuit diagram, you should draw a multiplexer as a box with "mux" on it. The inputs come in on the long side and the control is on the side. * N-to-1 multiplexer It is possible to construct a $2^n$-to-$1$ multiplexer with $n$ controls. For example, you can construct a $8$-to-$1$ multiplexer using $3$ controls. * Mux as a Look-up Table It is easy to implement a look-up table using a mux.