A combinational circuit comprises of logic gates whose outputs at any time are determined directly from the present combination of inputs without any regard to previous inputs.
A combinational circuit performs a specific information-processing operation fully specified logically by a set of Boolean functions.
The basic components of a combinational circuit are: input variables, logic gates, and output variables.
The 'n' input variables come from an external source whereas the 'm' output variables go to an external destination. In many applications, the source or destination are storage registers.
Design procedure of a Combinational Circuit
The design procedure of a combinational circuit involves the following steps:
The combinational circuit that performs the addition of two bits is called a half adder and the one that performs the addition of three bits (two significant bits and a previous carry) is a full adder.