74HC04 is used for inverting logic operations. 74HC04 is a six-inverter, that is, there are six inverters on one integrated block. The inverter input is high, the output is low, the input is low, the output is high. Boolean operations, also known as Boolean operations, used mathematical methods to study logical problems and successfully established logical calculus. He used equations to represent judgment, and reasoning as a transformation of the equations. The validity of this transformation does not depend on people's interpretation of symbols, but only on the combination of symbols. This logical theory is often called a Boolean algebra.