State Machine

There is a whole hierarchy of state machines. The most simple one is a Finite State Machine (FSM) or Finite State Automata (FSA). It has a finite list of states with an initial state, and transitions triggered by conditions (inputs). Apart from the states reflecting its instant situation, the FSM has no mechanism for remembering past operations. Going up the hierarchy ladder, more sophisticated state machines are augmented with increasingly versatile storage facility. The Turing Machine is on top with no restriction on the number of states it can enter in. The information treated by a FSM resides in the states and the events it reacts to. In the case of a Turing Machine, the information is also stored as symbols on the tape.