a) A mealy sequential circuit has one input (x) and one output (z). z can be 1 when the fourth, eighth, twelfth, etc. inputs are present, and z=1 if and only if the most recent input combined with the preceding three inputs was not BCD encoding of a decimal digit; otherwise, z=0. Assume the BCD digits are received least significant bit first. Derive a state table for the circuit. (Six states are sufficient.)
b) Repeat for Moore circuit, i.e, z=1 if and only if, after the fourth, eighth, twelfth, etc. inputs have been received, the previous four inputs were not valid BCD digit.
c) Is it possible for a Moore circuit to generate the correct output while the fourth bit is present rather than after it has been received?