A consideration of the minimum number of input terminals on universal logic gates and their realization

A detailed consideration is made of the strict minimum number of input terminals necessary on universal logic gates, allowing logic 0, 1 and the true and complement of each input variable to be connected to each input terminal. It is shown that a universal circuit capable of realizing all possible combinatorial functions of two input variables must have a minimum of three input terminals, whilst that capable of realizing all possible functions of three input variables must have a minimum of five input terminals. Circuits for both these minimum results have been achieved. An exhaustive consideration of all possible universal circuits for the two input case is also covered.