Optical Two-Step Modified Signed-digit Addition Based on Binary Logic Gates

摘要

A new modified signed-digit (MSD) addition algorithm based on binary logic gates is proposed for parallel computing. It is shown that by encoding each of the input MSD digits and flag digits into a pair of binary bits, the number of addition steps can be reduced to two. The flag digit is introduced to characterize the next low order pair (NLOP) of the input digits in order to suppress carry propagation. The rules for two-step addition of binary coded MSD (BCMSD) numbers are formulated that can be implemented using optical shadow-casting logic system.