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XScreenSaver(6x)                                              XScreenSaver(6x)



NAME
       munch - munching squares screen hack

SYNOPSIS
       munch  [-display  host:display.screen] [-foreground color] [-background
       color] [-window] [-root] [-mono] [-install]  [-visual  visual]  [-delay
       seconds]  [-xor]  [-noxor]  [-shift]  [-noshift]  [-logminwidth minimum
       width]

DESCRIPTION
       The munch program preforms the munching squares hack until killed.   It
       picks square size, position, and gravity randomly; configurable options
       are listed below.

       The munching squares hack cosists of drawing Y = X XOR T for a range of
       X  and  T  over and over until all the possible combinations of X and T
       have come up.  It was reportedly discovered by Jackson Wright  in  1962
       and took 5 instructions of PDP-6 code.

OPTIONS
       munch accepts the following options:

       -window Draw on a newly-created window.  This is the default.

       -root   Draw on the root window.

       -mono   If on a color display, pretend we're on a monochrome display.

       -install
               Install a private colormap for the window.

       -visual visual
               Specify  which  visual  to use.  Legal values are the name of a
               visual class, or the id number (decimal or hex) of  a  specific
               visual.

       -delay seconds
               How long to wait before starting over.  Default 5 seconds.

       -xor    Use the XOR drawing function.  (Default.)

       -no-xor Don't use the XOR drawing function.

       -shift  Start drawing the square at weird starting points.  (Default.)

       -no-shift
               Don't  shift  and  start  drawing  the square at weird starting
               points.

       -logminwidth minimum-width
               The logarithm (base 2) of the minimum with of a square (must be
               a power of 2, or some parts of the square aren't.)

ENVIRONMENT
       DISPLAY to get the default host and display number.

       XENVIRONMENT
               to  get  the  name of a resource file that overrides the global
               resources stored in the RESOURCE_MANAGER property.

SEE ALSO
       X(1),  xscreensaver(1),   http://www.inwap.com/pdp10/hbaker/hakmem/hak-
       mem.html, http://www.comedia.com/Hot/jargon_3.0/JARGON_M/MUNCHSQR.HTML

HISTORY
       Quoted  from  HAKMEM,  for historical interest.  As that document says,
       "Unless otherwise stated, all computer programs are in PDP-6/10  assem-
       bly language."

       ITEM 146: MUNCHING SQUARES
               Another  simple  display  program.  It is thought that this was
               discovered by Jackson Wright on the RLE PDP-1 circa 1962.

                   DATAI 2
                   ADDB 1,2
                   ROTC 2,-22
                   XOR 1,2
                   JRST .-4
               2=X, 3=Y. Try things like 1001002 in data switches.  This  also
               does  interesting  things  with  operations other than XOR, and
               rotations other than -22. (Try IOR; AND; TSC; FADR; FDV(!); ROT
               -14, -9, -20, ...)

       ITEM 147 (Schroeppel):
               Munching  squares  is  just  views of the graph Y = X XOR T for
               consecutive values of T = time.

       ITEM 148 (Cohen, Beeler):
               A modification to munching squares which reveals them in frozen
               states  through  opening  and closing curtains: insert FADR 2,1
               before the XOR. Try data switches =

                   4000,,4    1000,,2002    2000,,4    0,,1002
               (Notation: <left half>,,<right half>)

               Also try the FADR after the XOR, switches = 1001,,1.

COPYRIGHT
       Copyright (C) 1997 by Tim Showalter.  Permission to use, copy,  modify,
       distribute,  and  sell this software and its documentation for any pur-
       pose is hereby granted without fee, provided that the  above  copyright
       notice  appear  in  all  copies and that both that copyright notice and
       this permission notice appear in supporting documentation.   No  repre-
       sentations are made about the suitability of this software for any pur-
       pose.  It is provided "as is" without express or implied warranty.

AUTHOR
       Tim Showalter <tjsATandrew.edu>, 17-Jun-97, based on what's  in  the
       Jargon File and stealing stuff from existing xscreensaver modules.



X Version 11                  4.21 (01-Mar-2005)              XScreenSaver(6x)