Path: utzoo!utgpu!water!watmath!clyde!rutgers!gatech!ukma!psuvm.bitnet!cunyvm!ndsuvm1.bitnet!nu109703
From: NU109703@NDSUVM1.BITNET
Newsgroups: comp.sys.atari.8bit
Subject: Linking two computers
Message-ID: <578NU109703@NDSUVM1>
Date: 14 Feb 88 00:38:25 GMT
Organization: North Dakota Higher Education Computer Network, Fargo, ND
Lines: 62
DISCLAIMER: Author bears full responsibility for contents of this article.

I would like to be able to hook up two atari computers for interactive games,
etc. that require that you do not see the screen of the other person.
     
My brother and I both have Atari 800XL's with parallel ports.  I was wondering
if I could buy a parallel-to-parallel cord to use for data transmissions,
(for a game of battleship, for example).
     
If I could, then I want to write an interrupt routine for data tranmissions.
This, as you probably can see, is not necessary for a game like battleship,
but it would be great for some type of space or fast moving game.
That way you would not have to write special programs for two displays,
you could write a program in which the inputs would be from:
    (1) You - your keyboard and joystick inputs.
    (2) Other person - parallel interface inputs.
     
A program could then give a "personal" feel. You would always be the
#1 player, the subject of all attention.  Also, a program would not
be written for awkward sharing of the keyboard.
     
It may be difficult to decode the interface inputs, but I'm ready to
sacrifice a little work to get some type of interactive but still two
separate user system.
     
Can I do it?
If I could, I would probably send in the results to a magazine like
Antic or Compute (I'd like to get some money for it) and then I would
write some programs for it.  I have knowledge of machine language,
VBI's and DLI's.  I have the technical reference manual, but I find it
hard to understand sometimes, especially I/O, since I really don't have
the time for it.  I am hoping for a Co-op job this spring and summer,
so I'll be in the position that I want to be: working with computers,
but still free enough to use my time as I want to (No finals).
     
If the magazine accepts my ideas, I would then write programs that use
the two computers hooked up and possibly send them in.
     
I have never used the parallel interface before, so I don't know if it
is bidirectional or not.  If it is not, I could use the status lines and
hope I could figure a way to decode and encode them. (I.E. signals for
data, quit data, start data, ready to read or write, etc.)
Using the printer lines would also make it possible to use the disk drive
normally and store program results.  It would consist of a mutual agreement
between the programs that no data will be transferred and when the disk
operation is done, data may be tranferred again, possibly accomplished
by some internal flag that the interrupt routine works on.  This
could provide some SPECTACULAR computer-vs-computer games with a very
fast interrupt routine and some randomization in the programs.
     
Sorry, if I have gotten on an arctangent, but I think this would be a
good idea, even if difficult to implement.  But I think after it is
implemented, this could be used simply by building on a basic framework
for a program to be written.
     
Steve Lent - (ask me and I'll tell you what they called me in HS)
North Dakota State University
     
"If it breaks, buy a new one."
"If it doesn't break, the engineer doesn't know what he's doing and gets
fired."
     
Born on November 1, 1966: it was kind of nice to have halloween candy
and birthday presents at the same time.