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CS 140L Lecture 7. Professor CK Cheng 11/12/02. Transformation between Mealy and Moore Machines. Input: State Table of Mealy machine. 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
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CS 140L Lecture 7 Professor CK Cheng 11/12/02
Transformation between Mealy and Moore Machines Input: State Table of Mealy machine Algorithm: 1) For each NS, z = Si,j create a state Si(j) 2) For each new state Si(j), repeat the row PS = Si 3) Replace NS, z = Si,j with state Si(j). Set z = j for row PS = Si(j)
Example Mealy Machine: PS A B 00 A,0 A,1 01 A,1 B,0 10 A,1 B,0 (x,y) (NS, z) Moore Machine: PS A0 A1 B (x,y) 00 A0 A0 A1 01 A1 A1 B 10 B B B z 0 1 0
Mealy State Diagram 00/1 10/0, 01/0 10/0 B A 00/1
Moore State Diagram 10 01 00 10 A0/0 B/0 10 00 01 00 A1/1 01
Timing Diagrams Time step x y S z S z 0 0 0 A 0 A0 0 1 0 1 A 1 A0 0 2 1 0 A 0 A1 1 3 0 0 B 1 B 0 4 0 1 A 1 A1 1 5 0 1 A 1 A1 1 A Mealy A1 1 Moore (The output has a 1 clock shift between Mealy and Moore machines)
State Assignment 1) Binary – [ log2n ] 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
One hot: Qi = 1 iff present state = Si. 0 0 S0 S1 S2 1 1 0 1 X X X Q Q Q D D D Q’ Q’ Q’ X’ X’ X’ (X not true -> back to 1st FF, else to 2nd ) • Branch outs Fan-outs with AND gates. • Branch ins Collect tokens with an OR gate.