1
XScreenSaver(1)
XScreenSaver(1) XScreenSaver(1)
NAME
munch - munching squares screen hack
SYNOPSIS
deco [-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 ran-
domly; 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 possi-
ble combinations of X and T have come up. It was report-
edly 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.
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-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_MAN-
AGER property.
SEE ALSO
X(1) xscreensaver(1)
http://www.inwap.com/pdp10/hbaker/hakmem/hakmem.html,
http://www.comedia.com/Hot/jargon_3.0/JARGON_M/MUNCH-
SQR.HTML
HISTORY
Quoted from HAKMEM, for historical interest. As that doc-
ument says, "Unless otherwise stated, all computer pro-
grams are in PDP-6/10 assembly 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>)
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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 purpose 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
representations are made about the suitability of this
software for any purpose. It is provided "as is" without
express or implied warranty.
AUTHOR
Tim Showalter lt;tjs@andrew.cmu.edu, 17-Jun-97, based on
what's in the Jargon File and stealing stuff from existing
xscreensaver modules.