Binary/Gray To Gray/Binary Converter

The circuit converts a binary number into Gray code or a Gray code into a binary number depending on the state of the MODE input. Input to the circuit is through I3 to I0, the output terminals are O3 to O0. When MODE is logic 1 I3..I0 is converted from binary to Gray code, when MODE is logic 0 I3..I0 is converted from Gray code to binary.