The problem is to design a Nabs dispenser. The Nabs machine has two inputs, x and y, which encode the following information:
x y Meaning
0 0 nothing is happening
0 1 nickel inserted
0 1 dime inserted
1 1 Nabs button pushed
There is a single output, z. When z is 0, the machine produces nothing. When z is 1, the machine outputs a package of Nabs.
Assume that Nabs cost 15 cents. Nabs are returned only if the Nabs button is pushed after 15 cents are deposited. Assume that this %!@%$# machine returns no change and just keeps any money you deposit over 15 cents.
Draw the finite state machine for the Nabs dispenser below.