NFA: Vending Machine Simulation

1. NFA:Vending Machine Simulation Steven Stockall

2. Intro • NFA-Nondeterministic Finite Automaton - several possible states from current state, type of finite state machine • Goals: • Create a function NFA that works in a simulation • Gain a greater understanding to the use of and applications for finite state machines • Applications: • Vending Machine • Elevator • Circuit hardware

3. Design • Machine accepts dimes, nickels, and quarters • Monetary cap of $1 • Monetary states for all valid change inputs • Several purchase options: • Purchase items will vary in price • Invalid selections will return to current monetary state with prompt stating invalid selection • Valid selections will drop item and return correct change • ‘coin return’ button: • Returns change • Overflow: • Monertary input over $1 will be handled with an overflow state, this returns the amount of change equal to the amount over $1 entered into the machine by the user

4. Design (cont.) • Code: • Design will be implemented in C# • Design will have a small user interactive window with which the user can interact with and test the program

5. Code Organization • Main that starts the core program • Core: • Program starts with a $.00 state • based on user input will call one of the modules passing in the user input and the old state • modules will return new state • Module that handles monetary selection: • overflow will be handled within module • Module that handles item selection: • invalid selections return same state • valid selections return item adjust change amount and returns remaining change then returns to $.00 state • Module that handles coin return: • Returns coins • Returns to $.00 state

6. Testing • Correct State transition: • test to check state to state transition • Correct State chaining: • test to check state transitions are correct for long transition chains • Correct input handling: • Buttons work properly • Correct cash overflow handling: • purposely test all possible overflow states

7. Conclusion • Goals: • will be to see how a NFA works in real world applications • create a functioning NFA • create a workable vending machine simulation