States Single state: An automaton with one state, also called a combinational circuit, performs a transformation which may implement combinational logic. Finite states: An automaton that contains only a finite number of states. Infinite states: An automaton that may not have a finite number of states, or even a countable number of states. Different kinds of abstract memory may be used to give such machines finite descriptions. Stack memory: An automaton may also contain some extra memory in the form of a stack in which symbols can be pushed and popped. This kind of automaton is called a pushdown automaton. Queue memory: An automaton may have memory in the form of a queue. Such a machine is called queue machine and is Turing-complete. Tape memory: The inputs and outputs of automata are often described as input and output tapes. Some machines have additional working tapes, including the Turing machine, linear bounded automaton, and log-space transducer.
states single state an automaton with one state also called a combinational circuit performs a transformation which may implement combinational logic finite states an automaton that contains only a finite number of states infinite states an automaton that may not have a finite number of states or even a countable number of states different kinds of abstract memory may be used to give such machines finite descriptions stack memory an automaton may also contain some extra memory, in the form !of a stack in which sy!mbols can be pushed and popped this kind of automaton is called a pushdown automaton queue memory an automaton may have memory in the form of a queue such a machin:e is called queue machine and is turing-complete tape memory the i.nputs and outputs of automata are often described as input and output tapes some machines have additional working tapes including the turing machine linear bounded automaton and log-space transducer