Block Diagram of a Finite Automata
Finite Automata:
Analytically. a finite automaton can be represented by a 5tuple (Q, ∑, δ, q_{0}, F) where
i. Q is a finite nonempty set of states.
ii. ∑ is a finite nonempty set of inputs called the input alphabet.
iii. δ is a function which maps Q x ∑ into Q and is usually called the direct transition function. This is the function which describes the change of states during the transition. This mapping is usually represented by a transition table or a transition diagram.
iv. q_{0} ∈ Q is the initial state.
v. F ⊆ Q is the set of final states. It is assumed here that there may be more than one final state.
Components of a Finite Automata:
1. Input tape: The input tape is divided into squares, each square containing a single symbol from the input alphabet ∑. The end squares of the tape contain the end marker ¢ at the left end and the end marker $ at the right end. The absence of end markers indicates that the tape is of infinite length. The lefttoright sequence of symbols between the two end markers is the input string to be processed.
2. Reading head: The head examines only one square at a time and can move one square either to the left or to the right. For further analysis, we restrict the movement of the Rhead only to the right side.
3. Finite control: The input to the finite control will usually be the symbol under the Rhead, say a, and the present state of the machine, say q, to give the following outputs:

i. A motion of the Rhead along the tape to the next square (in some a null move, i.e. the Rhead remaining in the same square is permitted).
ii. the next stage of the finite state machine is given by δ(q, a).