Turing Machine simulator
------------------------

Written and Copyright (C) 1997 by Michael J. Gourlay

email: michael.gourlay at colorado-research dot com




Distribution
------------

The home site of tm is found through

  http://www.colorado-research.com/~gourlay/

From this page, surf through the "Software" links to the Computer-Theory
section.




Compiling
---------

To build "tm", type "make depend" then "make".




Execution
---------

Read the "tm.man" file for details on running tm.




Example 1:
  tm -m stop-r-1.tm -t one.tape -d

This will run a simulation of a Turing Machine which searches its tape
to the right for a '1' and stops.  If the portion of the tape to the
right of the initial tape position is blank, then this machine never
stops.  In this example, "tm" is started in "debug" mode, which means
that the machine will not do anything until a key is pressed.  The
machine will step one instruction per key press.  If you press the "d"
key, the machine toggles in and out of "debug" mode.  If you press the
"Escape" key, the machine will stop.  Try running this 'stop-r-1'
machine on different tapes.  One interesting thing to notice about
the "stop-r-1" Turing Machine is that if you run it on a blank tape,
the tape will grow until your machine runs out of memory.


Example 2:
  tm -m flip.tm -t bits.tape -d

The machine 'flip.tm' will flip the bits of its tape which have
positive indices.  The machine never stops.


Example 3:
  tm -m bb-501.tm -t zero.tape -V

The machine 'bb-501' is called a Busy Beaver.  This particular Busy
Beaver has 5 states.  Its purpose is to write as many 1s on a blank
tape as possible.  If you ran this machine in visual mode, it would
run for a very long time.  Notice that the above option has a capital
V not a lower-case v.  This prints the state transition table, the
initial tape, the final tape, and some other information about the
execution.



Have a look at the other Turing Machine examples.



Several examples of machine files and tape files which are designed to
fail are included with this package.  They are for testing the error
trapping code.  Do not be surprised if you find that some of the files
produce error messages, especially if their comments indicate that they
are designed to produce errors.