This is an instance of a simple state-machine. From the initial state, either 0 or 1 is entered by first set a DIP switch and pressing the push-button. When entire key sequence has been entered, another DIP switch (named Open) is set and push-button is pressed to tell the state-machine the end of the sequence. In this lab, the length of the sequence is 3-bit and its combination can be arbitrally set by three DIP switches. If wrong sequence is entered, or Open is not set exactly at the end of the 3rd bit, the state-machine returns to the initial state. Figure 0.1 shows the state transition diagram of this combination lock. mn means nth bit is correct. Arrows without conditions are default transitions.
Figure: Combination Lock: State-Transition Diagram
