OPTICAL MODIFIED SIGNED-DIGIT ADDITION BASED ON BINARY LOGICAL OPERATIONS

We propose here the realization of modified signed-digit (MSD) additio n using traditional binary logical operations. The trinary logical ope rations required in MSD additions can be considered as the 'signed' ve rsion of the logical XOR and AND operations performed in binary additi on. Therefore, MSD additions can be implemented by binary logic gates if the sign information is extracted first and then restored to the bi nary output. This approach results in an efficient design of optical a rithmetic and logic unit (ALU) as the binary logic gates can be common ly used to perform both logic and arithmetic operations.