Xchomp, Version 1.1
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COMPILING THE PROGRAM

Xchomp has been tested here on the following machines:

	-- Sun 3/50, 3/75, 3/60, 386i
	-- DEC VAXstation 2000, VAXstation 3100
	-- Stellar

Here is a performance chart:

Machine			Monochrome			Color
-------			----------			-----

Sun 3/50, 3/75	   -->  A BIT SLOW			N/A
Sun 3/60	   -->  RUNS NICELY			N/A
Sun 386i	   -->  RUNS NICELY			too slow

VAXstation 2000		too slow			too slow
VAXstation 3100    -->	SCREAMS!		   -->	SCREAMS!

Stellar			N/A			   -->	SCREAMS!

The program can be compiled in two ways -- the normal way, which
results in the program running at maximum speed, which is way too
fast on systems like the Stellar and the VAXstation 3100, but just
right for the Sun 3/60.  The other way is to add "-DFRAME_DELAY=xxxxx"
to the CFLAGS in the Makefile.  This causes a delay of the specified
number of microseconds between each frame of motion.  This delay should
be 20,000 microseconds or under.  Adding "-DFRAME_DELAY=20000" works
beautifully for the VAXstation 3100 and the Stellar.

If you're porting xchomp to another machine, I suggest you compile it
without the "-DFRAME_DELAY=xxxxx", and if the result is too fast, then
try several values for the delay.

I have received several responses from people who have built xchomp
on the Sun Sparcstation and DEC DECstation lines of RISC machines;
they have reported good performance.  The game has also been compiled
on color IBM machines running the AIX operating system.  For some
reason, performance on even the fastest of these has been pretty bad.
I cannot understand why a 40+ MIPS IBM machine runs xchomp 4 times
more slowly than a 3 MIPS Sun workstation.

RUNNING THE PROGRAM

First off, let me just state that this program is to be run with ALL
OTHER PROCESSES ASLEEP!  Even so, on my 3/60, there are times when
the animation gets choppy and uneven for a while.  This is probably
due to some background process waking up and doing something.  Don't
expect perfectly smooth motion under the X window system, and don't
even try to play the game while compiling something in the background.
And if you're a perfectionist, then get rid of the second hand on your
xclock!  I'm serious.

If you're using a window manager such as TWM, in which the input focus
belongs to the window containing the pointer, there's something to consider.
On monochrome Suns, it's best to force the focus on the xchomp window and
get the pointer out of there before playing the game.  This is because if
the pointer is in the middle of the window, it'll blink during each motion
cycle and cut the performance in half.  Another solution is to place the
pointer at the VERY BOTTOM of the window, below the little icons representing
the number of lives left.  If you iconify xchomp, and bring it back, it comes
back in a paused state, so you can place the pointer back at the bottom of
the window before you continue.  This whole thing doesn't seem to be a
problem on monochrome VAXstations and color systems.  I'll try to find
a better solution for a future posting.

NOTES TO PROGRAMMERS

Xchomp uses pure Xlib, without toolkits, widgets, etc.  This is mainly
because I don't know anything about toolkits, widgets, etc.  In fact,
this program started out as an experiment in X Window System programming;
I didn't know anything about that either.  While making this game, I always
had an open copy of the Xlib Reference Manual and the Xlib Programming Manual
at my side.  The main goal for xchomp has been to create motion as smooth and
flicker-free as possible under X Windows.

The source code has been cleaned up somewhat for Version 1.1.  Many variable
names have been changed to more descriptive ones.  I believe that most of the
code should be fairly clear.  Of course, it is my code, and I could be very
mistaken about its clarity.
---
+--------------------+-----------------------+-------------------------------+
|                    |  Polygen Corporation  |           UUCP:               |
|  Jerry J. Shekhel  |   Waltham, MA 02254   |  {princeton, mit-eddie,       |
|                    |    (617) 890-2888     |  buita, sunne}!polygen!jerry  |
+--------------------+-----------------------+-------------------------------+