22 March, 2000

A word about the homework

• How to compute 3*x + 1 on the PIC
• How to compute x/2 on the PIC
• How to test for oddness on the PIC

Types of state machines

• Moore FSM -- state based
• Mealy FSM -- input (and state) based

FSM minimization

Equivalence classes can be used to determine identical states. This rarely happens unless the FSM designer is careless.

State assignment

minimum bit change

Weigh each arc by the number of bits that change in going from one state to another.

prioritized-adjacency strategy

Assign adjacent states by priority:

1. Same next state for a given value
2. Next states of a single state
3. Same outputs for a given input

hot-one encoding

Each state have its own bit.

Computer assigned states -- nova

.symbolic input
no_action 0_cents 0_cents 0 
no_action 5_cents 5_cents 0 
no_action 10_cents 10_cents 0
no_action 15_cents 15_cents 0
nickel 0_cents 5_cents 0 
nickel 5_cents 10_cents 0
nickel 10_cents 15_cents 0
nickel 5_cents 15_cents 0
dime 0_cents 10_cents 0
dime 5_cents 15_cents 0
dime 10_cents 15_cents 0
dime 15_cents 15_cents 0
button_press 0_cents 0_cents 0 
button_press 5_cents 0_cents 0 
button_press 10_cents 0_cents 0 
button_press 15_cents 0_cents 1
.end

Input encoding