Moore Machine

• State Diagram: Pictorial representation of a sequential circuit
  • Graph consisting of nodes and directed arcs
    • Nodes represent circuit states
    • Arcs represent transition between states
• State Table: Describes the behavior of a sequential circuit in tabular form

Example §

Circuit Specification §

• The circuit has one input w and one output `z
• All changes in the circuit occur on the positive edge of a clock signal
• The output z is equal to 1 if during two immediately preceding clock cycles the input w was equal to 1, otherwise the value of z is equal to 0

State Diagram §

State Diagram for the circuit specification given above

• Node A represents the starting state and it is also the state the circuit will reach after an input w = 0 is applied
  • In this state, output z is 0, which is indicated as A/z = 0 in the node
  • The circuit remains in state A as long as w = 0 (indicated by an arc with a label w = 0 that originates and terminates at this node)

Number of arcs originate from a node is $2^n$, where n is the number of inputs (in this example n = 1)

Didn’t write the rest of them as it should be common sense from here…

State Table §

State-assigned Table §

I don’t really get this well right now

Circuit Block Diagram §

Since there are 3 states in our example, at least 2 flip-flops are needed

Generic block diagram where $y_1$ and $y_2$ are the present-state variables