Combinational logic

Abstract

COMBINATIONAL LOGIC in electronic engineering enables the processing of information that is effectively in the form of binary numbers, since the inputs and output(s) of a logical circuit can be in only one of two states. The output state is a function of the input states, and can be used to control some other device or machine or circuit, or can just be used as information. Figure 20.1 shows schematically what combinational logic does. Two-state inputs can be expressed as two-state variables, or Boolean¹ variables, which can be combined according to the rules of Boolean algebra. In formal terms we can write

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where Q is the output and A, B, C, D etc. are the inputs.