3. A rotary shaft position measuring system of the type including rotation detecting means for generating a plural bit coarse count binary word and a plural bit fine count binary word, coarse/fine count comparator means, responsive to a predetermined number of overlapping bits of the coarse and fine count words, for providing command signals for correcting the non-overlapping portion of the coarse count word prior to combining with the fine count word to provide a combined binary word representing shaft position, said system being characterized by the improvement wherein said comparator means comprises: a plurality of first inverter means, corresponding in number to said predetermined number, for inverting said overlapping bits of said coarse count binary word; a plural bit binary full adder means for subtracting said overlapping bits of said coarse count binary word from said overlapping bits of said fine count binary word to provide a .SIGMA.N output, where N is said predetermined number, and a carry out output; first AND gate means, responsive to said .SIGMA.N and said carry out outputs, for providing as one of said command signals a first true output only when both of said .SIGMA.N and said carry out outputs are true; second inverter means for inverting said .SIGMA.N and said carry out outputs; and second AND gate means, responsive to outputs of said second inverter means, for providing as another of said command signals a true output only when both of said .SIGMA.N and carry out outputs are not true.
5. A system as defined in claim 3, and further comprising: correction means, responsive to said command signals and to said coarse count binary word to add one count to, subtract one count from, or do nothing to the non-overlapping portion of said coarse count binary word prior to said combining thereof with said fine count binary word.