Below is a sequential circuit and the skeleton of a state diagram.  You will reverse engineer the circuit to re-derive the state diagram by following the steps and answering the questions below.

Is the circuit above a Mealy or Moore machine?  _____Moore_____

What are the next state equations (for D1, D2, D3)?

   D1 =  in

   D2 =  Q1

   D3 =  (Q1Q2) xor (Q3)

Start at state 000 (Q1 = 0, Q2 = 0, Q3 = 0) and complete the state diagram below.  Show all state transitions from state 000 (for both in = 0 and in =1) and for each state reachable from 000.  Please put all the in = 0 transitions on the top and all the in = 1 transitions on the bottom.
 
 

Extra Credit (3 points): What does this machine do?

This machine is a serial stream framer.  Q2 is simply the input delayed by 2 clock cycles (through the Q1-Q2 shift register). Q3 toggles whenever two consecutive ones are seen in the input stream.  This is very similar to what you will do for the Framer state machine of assignment #9 except that there the framing condition is 1110 instead of just 11.