combinational logic intro

		Introduction
		Combinatorial Circuits are circuits which can be considered to have the following generic structure.
		Whenever the same set of inputs is fed in to a combinatorial circuit, the same outputs will be generated. Such circuits are said to be stateless. Some simple combinational logic elements that we have seen in previous sections are "Gates".
		All the gates in the above figure have 2 inputs and one output; combinational elements simplest form are "not" gate and "buffer" as shown in the figure below. They have only one input and one output.