The HCC40181B (extended temperature range) and HCF40181B (intermediate temperature range) are monolithic integrated circuits, available in 24lead dual in-line plastic or ceramic package and plastic micro package. The HCC/HCF40181B 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 logical mode, and addition, subtraction, decrement, left-shift and straight transfer in the arithmetic mode, according to the truth table. The HCC/HCF40181B operation may be interpreted with either active-low or activehigh data at the A and B word inputs and the function outputs F, by using the appropriate truth table. The HCC/HCF40181B contains logic for full look-ahead carry operation for fast carry generation using the carry-generate and carry-propagate outputs G and June 1989