The Simplification of Multiple-Output Switching Networks Composed of Unilateral Devices

The purpose of this paper is to show that two-level (no more than two gates in cascade) multiple-output switching networks composed of unilateral switching devices such as diodes can be simplified or minimized in much the same manner as single-output networks. This is accomplished by extending the notation and techniques used in the simplification of two-level single-output switching networks to multiple-output switching networks. A simple procedure for identifying multiple-output prime implicants is devised and, as a final result, an algorithm is presented which can be used to minimize the switching network corresponding, to a number (q) of given Boolean expressions of the same variables. This algorithm is based on the Quine rules but has been modified to take advantage of the so-called ``don´t care´´ conditions which occur because some inputs are forbidden or because some outputs are of no concern. This algorithm can readily be programmed on a digital computer if desired.