Two-step digit-set-restricted modified signed-digit addition-subtraction algorithm and its optoelectronic implementation

A novel, to our knowledge, two-step digit-set-restricted modified signed-di git (MSD) addition-subtraction algorithm is proposed. With the introduction of the reference digits, the operand words are mapped into an intermediate carry word with all digits restricted to the set {(1) over bar, 0} and an intermediate sum word with all digits restricted to the set {0, 1}, which c an be summed to form the final result without carry generation. The operati on can be performed in parallel by use of binary logic. An optical system t hat utilizes an electron-trapping device is suggested for accomplishing the required binary logic operations. By programming of the illumination of da ta arrays, any complex logic operations of multiple variables can be realiz ed without additional temporal latency of the intermediate results. This te chnique has a high space-bandwidth product and signal-to-noise ratio. The m ain structure can be stacked to construct a compact optoelectronic MSD adde r-subtracter. (C) 1999 Optical Society of America.