Optimal and Near-Optimal Universal Logic Modules with Interconnected External Terminals

Abstract

A universal logic module (ULM) with interconnected external terminals contains m input terminals and s auxiliary function terminals. The module implements the function U( Z1, Z2,...,Zm) such that every Boolean function of n variables f( x1, x2,* .* * X,n) can be realized by an appropriate substitution of an element of 5= { xl,x1,x2,x2,...,Xn,xn,g1,g2,..., gs} for each zj. An improved lower bound on the minimum number of terminals of a ULM of this type is derived. It is shown that certain of the " best-known" designs are in fact optimal. Improved designs are presented for ULM's of nine and ten arguments.