On parallel Turing machines with multi-head control units

This paper deals with parallel Turing machines with multi-head
control units on one or more tapes which can be considered as a
generalization of cellular automata. We discuss the problem of
finding an appropriate measure of space complexity. A definition is
suggested which implies that the model is in the first machine
class. It is shown that without loss of generality it suffices to
consider only parallel Turing machines of certain normal forms.