TURING MACHINE
--------------

For a good, short description of Turing Machines, see the article by
J.L. Lawrence in Dr. Dobb's Journal, Number 51, January 1981. See also
various issues of Scientific America, particularly the Computer Recreations
column, and countless other books and articles in any good library.

To test the program, try the following:

- at the COMMAND prompt, type ENTER
- you are then prompted for instructions, enter

# 1 0aA0
# 2 0AR0
# 3 0bB0
# 4 0BR0
# 5 0 1
# 6

- at the COMMAND prompt, type TRACE
- at the COMMAND prompt, type GO
- enter the input tape:

ababba

and 1 for the initial tape head position

- you will see the sequence of steps taken by the machine, the final tape,
and the final head position.

The menu options WRITE and READ allow you to store on or retrieve from disk
user programs.

Don't be afraid to experiment. If you make a mistake, error messages are
displayed.

Remember that, no matter how simple and slow this Turing Machine may be,
your computer is nothing but a glorified version of it! That is why it
is more aptly called a Universal Turing Machine.

This program was originally written by J.L. Lawrence in BASIC-PLUS for the
PDP 11/45. It has been translated into QuickBasic 4.5 and slightly revised
by the present author. Any comments and questions may be sent to him:


Luigi Bianchi 414 Atkinson College York University
4700 Keele St. North York Ontario M3J 1P3 Canada