Quote Originally Posted by Guv
I think a Turing machine can only do a few operations (less than 10-20). Try a Web search to find out what operations are allowed. It should be a lot simpler to understand than the posted description of this hypothetical device.

Turing proved that his simple machine could do anything that more complicated machines could do. Since it was easier to analyze than a complex device, it could be used to determine the theoretical capabilities of more complex systems.
10-20, where did you get that number?
There should only be one kind of instruction, which looks like this:
(StateA, StateB, Read, Write, Direction)

For instance, if I have a tape looking like this:

[..A,B,C,D..]

the head is on B, and the TM is in state X,

and we have this instruction:

(X,Y,B,E,Right)

then what follows is

[..A,E,C,D..]

the head is now on C, and the TM is in state Y.