The 74HC/HCT181 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no. 7A.
The 74HC/HCT181 are 4-bit high-speed parallel Arithmetic Logic Units (ALU). Controlled by the four function select inputs (S0to S3) and the mode control input (M), they can perform all the 16 possible logic operations or 16 different arithmetic operations on active HIGH or active LOW operands (see function table).