Derivation of universal logic modules, for n ¿ 3, by algebraic means

Universal logic modules (ULMs) are digital circuit configurations which, by appropriate connection to their input terminals, can be made to realise all possible combinational logic functions of a given number of independent binary input variables. The paper describes a method for deriving ULM circuits in general, and in particular considers circuits with three input variables. These are known to need at least five input terminals, and several circuit configurations with this minimum number exist in the literature. The paper discloses five more; four of the five involve negation of the output, but the fifth does not.