Q. Demonstrate how finite state machine model helps in designing a switching system and give a typical illustration.

Ans:

Switching systemessentially belongs to class of finite state machines (FSM) which are asynchronous in nature and follows a sequential logic for their operation. They can be modelled by using a memory part and a combinational part as displayed in Figure. In FSM status of the output circuits not only depends upon inputs but also upon current state of machine. Asynchronous sequential operation gives rise to many problems because of transient variations that can take place in logic circuits and memory elements. Clocked synchronous operation displayed in figure overcome such problems.