ABSTRACT
Processors are digital circuits. A digital circuit is an electrical circuit in which voltage is treated as a signal. These signals carry information, and the components of the circuit process the information. The number of signals is limited. A combinational circuit is a direct hardware implementation of a Boolean function. Combinational circuits consist of components that compute operations, and connections that carry Boolean signals to and from the operator components. The components of a digital circuit are called gates. Gates are built to do all of students' common Boolean operations. Each operation in the expression is implemented by one of the common gates. The gates are wired together to feed an output of one operation as the input to another appropriate operation. An analogy to the operation of a decoder might be a hypothetical room, with a keypad on the wall. The keypad accepts numbers between zero and three.
