The CD40181BMS is a low power four bit parallel arithmetic logic unit (ALU) capable of providing 16 binary arithmetic operations on two four-bit words and 16 logical functions of two Boolean variables. The mode control input M selects logical (M = High) or arithmetic (M = Low) operation. The four select inputs (S0, S1, S2, and S3) select the desired logical or arithmetic functions, which include AND, OR, NAND, NOR and exclusive-OR and-NOR in the logic mode, and addition, subtraction, decrement, left-shift and straight transfer in the arithmetic mode, according to the truth table. The CD40181BMS operation may be interpreted with either active-low or active-high data at the A and B word inputs and the function outputs F, by using the appropriate truth table.