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					Finite State Machines
      AS and A2 compared
• AS Revision
  – Finite state machines with output
    • Mealy machines
  – Finite state machines without outputs
  – State Transition Tables
  – Decision tables
         A2 new topics
– State Transition Diagrams
– Finite state machines with output
  • Mealy and Moore machines
– Finite State Automata
  • Deterministic FSAs (DFAs)
  • Non-Deterministic FSAs (NFAs)
    Revision: Mealy Machines
                                         Output on Transition
• Using Boole Deusto

• First task – ballpoint
  pen.
• Two states, retracted
  and extended. Input
  is either a click (1) or
  fumble (0). Output is      Transition table for ballpoint pen
  ready to write (1) or      Current       R      R     E         E
  not ready to write (0)     Input         1      0     1         0
                             Next          E      R     R         E
                             Output        1      0     0         0
             Challenge
• Using Boole Deusto or JFLAP:
• Create a machine that outputs 0 unless
  it sees the sequence 111, in which
  case it outputs a single 1.
• Create a vending machine which takes
  either 5p or 10p and gives 15p sweets
  plus change.
Revision – FSMs without outputs
• Ultra-Basic combination
  lock.
• Two digit code ‘20’
• Numbers 012

• Start State
• Accepting State           Decision Table
                            First is 2       Y   Y   N   N
• Use software VAS          Second is 0      Y   N   Y   N
                            Output Pass      Y   N   N   N

				
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