From Zero to One

This chapter introduces principles for understanding and designing complex systems. It explains that although the real world is analog, digital designers discipline themselves to use a discrete subset of possible signals. In particular, binary variables have just two states: 0 and 1, also called FALSE and TRUE or LOW and HIGH. Logic gates compute a binary output from one or more binary inputs. Logic gates are commonly built from CMOS transistors, which behave as electrically controlled switches. nMOS transistors turn ON when the gate is 1. pMOS transistors turn ON when the gate is 0.