Introduction - If you have any usage issues, please Google them yourself
Designs four ways according to the selector, its function is
chooses four groups of different data according to the request an
output Output that group of data has two controls signals to decide,
its truth table as follows: Data access control end output data Input0
Input1 output 0 0 output0 0 1 output1 1 0 output 21 1 output 3