#### Abstract

PURPOSE: To shorten the time required for calculation processing by inputting a signal adapted to various calculation modes as the input signal of a carry input control circuit to perform addition and subtraction between two input calculation data and +1 increment and -1 decrement of one input operation data.
CONSTITUTION: A full adder 1, AND circuits 31 and 32, exclusive OR circuits 21 and 22, and a carry input control circuit 40 are provided, and the carry input control circuit 40 is provided with a NOR circuit 41, an AND circuit 42, and an exclusive OR circuit 43. Logical values of carry input control signals C, D, E, and F inputted to input terminals 12W15 are combined to perform A+B calculation, A+B calculation, B-A calculation, A+1 calculation, B+1 calculation, A-1 calculation and B-1 calculation.
COPYRIGHT: (C)1988,JPO&Japio