A control mechanism for a vending machine accepts nickels and dimes. It dispenses merchandise when 20 cents is deposited; it does not give change if 25 cents is deposited. Design the FSM asynchronous circuit that implements the required control, using as few states as possible. Determine the suitable state assignment and derive the minimum next-state and output expression.

A control mechanism for a vending machine accepts nickels and dimes. It dispenses merchandise when 20 cents is deposited; it does not give change if 25 cents is deposited. Design the FSM asynchronous circuit that implements the required control, using as few states as possible. Determine the suitable state assignment and derive the minimum next-state and output expression.