An Electronic Karnaugh Map Plotter for Four-Variable Binary Logic Functions

Introduction In the teaching ofboth combinational and sequential logic, widespread use is made of the Karnaugh Map diagramu2) in order to graphically display the standard products or 'minterms' ofbinary logic functions. As is well appreciated, this particular two-dimensional map representation is ideal for situations containing not more than four binary variables, but cannot be extended to greater than four without losing its great diagrammatic convenience and 'readability'. It is usual practice to draw this map layout when required, and use it by 'ticking' or otherwise marking appropriate squares in the layout corresponding to the minterms whose value is '1' (or '0' depending on choice). For example, the minterms and hence map marking for a four-variable binary function ABcD would be as shown in Fig. l(a), whilst for [A + BD] the map would be as shown in Fig. 1(b).