Introduction to Synchronous State Machine Design and Analysis

Combinational logic devices lack true memory, and, therefore, lack the ability to perform sequential operations. Yet their presence in a sequential machine may be indispensable. This chapter defines that sequential machines, or simply state machines, possess true memory and can issue time-dependent sequences of logic signals controlled by present and past input information. These sequential machines may also be synchronous because the data path is controlled by a system clock. In synchronous sequential machines, input data are introduced into the machine and are processed sequentially according to some algorithm, and outputs are generated—all regulated by a system clock. The chapter also highlights the synchronous sequential machines and their design, analysis, and operation. A sequential machine always has a finite number of states and is therefore called a finite state machine (FSM) or simply a state machine. Thus, if there are N state variables, there can be no more than 2 N states in the FSM and no fewer than 2.