TABLE OF CONTENTS The digital system consists of two types of circuits, namely
Combinational circuits and
Sequential circuits
A combinational circuit consists of logic gates, where outputs are at any instant and are determined only by the present combination of inputs without regard to previous inputs or previous state of outputs. A combinational circuit performs a specific information-processing operation assigned logically by a set of Boolean functions. Sequential circuits contain logic gates as well as memory cells. Their outputs depend on the present inputs and also on the states of memory elements. Since the outputs of sequential circuits depend not only on the present inputs but also on past inputs, the circuit behavior must be specified by a time sequence of inputs and memory states. The sequential circuits will be discussed later in the chapter.
In the previous chapters we have discussed binary numbers, codes, Boolean algebra and simplification of Boolean function, logic gates, and economical gate implementation. Binary numbers and codes bear discrete quantities of information and the binary variables are the representation of electric voltages or some other signals. In this chapter, formulation and analysis of various systematic design of combinational circuits and application of informationprocessing hardware will be discussed.
A combinational circuit consists of input variables, logic gates, and output variables. The logic gates accept signals from inputs and output signals are generated according to the logic circuits employed in it. Binary information from the given data transforms to desired output data in this process.
