Summary: Theory of Computation
Lecture 10: Turning Machines
University of South Carolina
February 14, 2012
We have already studied some computing models:
Finite automata are good model for devices that have small
amount of memory;
Pushdown automata are good models for devices that have an
unlimited but LIFO-type of memory.
However, as we have seen, some very simple tasks are still beyond
the capabilities of these models. We need a new model that would
represent general purpose computers.
Turing machine (TM) was first proposed by Alan Turing in 1936.
It is similar to finite automata but has unlimited and unrestricted
memory. Hence, it is a more accurate model of general purpose
The TM model uses an infinite tape as its memory. It has a tape