I was teaching an engineering class the other day, and notice that my students were lost when I mentioned Finite Automata or Finite State Machine. I guess I have to give them a brief introduction to Automata. Can anybody suggest a good reference on FA (preferably available on the Internet)? One that can be presented in one (2-hour) class. On a similar note, I am also looking for a good explanation on BNF notation. I forgot where I learned those things, Hopcroft & Ullman perhaps? (but this is to detailed for my students).