After the time step, the machine moves to a new state. The main problem when programming Turing machines is that there is really no place to store data other than the tape. Therefore it becomes hard to process more than one symbol at a time. Comparisons of data consisting of more than one symbol, for example, require placeholders and a large number of states to hold information needed. Soon, even for seemingly simple operations, the number of states grows to huge proportions.
Abstraction is almost impossible.
It is hard to imagine the equivalent of a procedure call. This makes it a hard task to divide up a problem into subproblems. One could imagine a Turing machine operating directly on the code for a register machine , combining registers to form the state. Theoretically, this is not a problem, though, as long as there is an upper boundary on both. Register machines Your browser does not support Java.