1. CS 140L Lecture 7 Professor CK Cheng 11/12/02

2. Transformation between Mealy and Moore Machines Algorithm: 1) For each NS, z = S i, j create a state S i (j) 2) For each new state S i (j), repeat the row PS = S i 3) Replace NS, z = S i, j with state S i (j). Set z = j for row PS = S i (j) Input: State Table of Mealy machine

3. Mealy Machine: Example PS A B 00 A,0 A,1 01 A,1 B,0 10 A,1 B,0 (x,y) (NS, z) PS A0 A1 B 00 A0 A1 01 A1 B Moore Machine: 10 B (x,y) z 0 1 0

4. Mealy State Diagram A 10/0 B 00/1 10/0, 01/0

5. Moore State Diagram A0/0 A1/1 B/0 10 00 10 01 00 01

6. Timing Diagrams Time step x y S z S z 0 A 0 A0 0 1 0 1 A 1 A0 0 2 1 0 A 0 A1 1 300B1B0300B1B0 4 0 1 A 1 A1 1 5 0 1 A 1 A1 1 Mealy Moore (The output has a 1 clock shift between Mealy and Moore machines) A A1 1

7. 1) Binary – [ log 2 n ] bits 000,001,110, etc. 2) Gray – can change by only 1 bit i.e. 000-> 001->011->010. 3) Johnson - [ n/2 ] (bits) number of flip flops. 4) One hot – n FF, n states State Assignment

8. One hot: Q i = 1 iff present state = S i. S0 0 S1 0 1 S2 1 0 1 D Q Q’ X X’ D Q Q’ X X’ D Q Q’ X X’ (X not true -> back to 1 st FF, else to 2 nd ) 1)Branch outs  Fan-outs with AND gates. 2)Branch ins  Collect tokens with an OR gate.