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3]AutomaLab
3]By Michael Creutz
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     Play creator with your own universe. With AutomaLab you control the
microphysics of a discrete world of cellular automata. This two-dimensional
land is an array of 192 by 180 cells displayed as pixels on the Amiga screen.
Each cell can be alive or empty, with evolution occurring in discrete time
steps. Empty cells are black, newborn ones are yellow, older living ones are
red, and cells that have just died are magenta. 
     In one time step, the fate of each cell depends on the total number of
living neighbors. Using Boolean gadgets, you control when a new live cell
will be born on an empty site and when a living one will survive. Another
gadget determines whether the cells count only their four nearest neighbors
or also include the nearest cells in the diagonal direction, for a total of
eight neighbors. With menu selections you can determine whether the boundary
of your universe is dead, alive, or periodic. The speed, pause, and clear
gadgets should be self explanatory. You can also sketch new live cells by
pressing the left mouse button over your world. 
     There are 2^18=262,144 possible rules with the eight neighborhood, and
2^10=1,024 more with the four cell neighborhood. Indeed, it is unlikely that
you will be able to try them all.
     The program starts out with Conway's classic cellular automaton model
"life." Here a new cell is born for exactly three neighbors, while a living
cell dies with less than 2 (lonely) or more than 3 (overcrowding) neighbors. 
     Another well-known rule is Fredkin's modulo two model which uses the 4
cell neighborhood. Here a state flips if it has an odd number of active
neighbors and is unchanged otherwise. Start with some small picture and
observe how the initial state is replicated.
     The C source compiles with PDC, using the standard Commodore 1.3
includes. It uses direct access to the blitter for speed. You exit the
program either via the menu or by pressing escape or any control key.
     This distribution consists of the following files:

      AutomaLab        the executable program
      AutomaLab.info   the icon
      AutomaLab.doc    this file
      AutomaLab.c      the C source

     (JUMPDISK NOTE: This text file and the C source have been crunched for
disk storage savings. See the article on decrunching on the Articles Menu.)

3]ACKNOWLEDGEMENT
     This program has been authored under contract number DE-AC02-76CH00016
with the U.S. Department of Energy.  Accordingly, the U.S. Government retains
a non-exclusive, royalty-free license to publish or reproduce the published
form of this contribution, or allow others to do so, for U.S. Government
purposes.


3]FURTHER READING
     M. Gardner, Scient. Am. 223 (4), 120-124; (5), 118; (6), 114 (1970).
     The entire issue of Physica D 10, (1984).
     S. Wolfram, Theory and Applications of Cellular Automata, World
Scientific (1986).

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