From: Rick_Michael_Cortese@cup.portal.com
Newsgroups: comp.sys.atari.8bit
Subject: Re: Connecting an RS232 modem to an Atari?
Date: Tue,  8 Sep 92 11:11:42 PDT
Organization: The Portal System (TM)
  <65456@cup.portal.com>

Rick Cortese     2/13/91
20802 Laurel Road
Los Gatos, CA 95030

How to attach RS-232 devices to a joystick port.

1st I'd like to apologize for the verbose instructions
<grin>.

For those people that are worried about whether or not I have
real serial ports, the answer is yes:  Both an 850 &
PR:Connection.  The reason I looked into this is I felt we
were loosing people from the Atari community when we
recommended the standard methods of transferring data, that
is:  Buy a disk drive for $200, a $16 cable, an $80
interface, and a $10 null modem.  Although it was never said,
I know most people probably balked at spending $300+ on a
computer with a street value of $50.  I imagine most of them
just bought a clone for a couple of extra bucks.  With that
in mind I paid little attention to doing this right and a lot
of attention to doing it cheap.

The 1st thing you'll need is a joystick cable.  Just about
any cable that works with the Atari or 2600 VCS is suitable.
B&C Computer Visions sells cables for $1.50 & I know San Jose
Computer used to sell joystick extension cables for a buck or two.
I'd recommend salvaging one from a busted joystick if possible.
The other parts are readily available from Radio Shack or JDR
Micro Devices in San Jose (My personal favorite).  JDR's toll free
number is 800-538-5000.  JDR's minimum charge is $10 + $2.50 P&H
so you may want to pick up some other goodies at the same time,
like a V20 for your IBM or maybe some SIMs for your ST.

I also wrote a two short BASIC/ML routines for transferring
test files between the 8-bit Atari to my ST and clone.  I've
included the source code for anyone who'd like to see how
it's done.  If you have an assembler you may want to see how
fast you can get the transfers to go.  The one from the
receiving data isn't as short as it could be, but it was
short enough that I didn't bother optimizing it.  You're
limited to transferring files that are less then 30,000 bytes
long, but this should be enough to transfer a MPP type
telecommunication program, MPP was the Co. that developed a modem
that plugged into joystick port(2), type.  I didn't bother
figuring out how to transfer binary files to the 8-bit from an ST
because I hate ST basic that much.  I could've done it in 'C, but
I think most people that have an ST also have enough software for
the 8-bit to get the set-up to work.  There are many BBS's that
have EXPRESS.MPP or the MPP drivers,  people like B&C Computer
Visions in Santa Clara CA that sell public domain software for $3
or $4, and user groups where you can get a copy.  If it's a
problem, let me know & I'll do it.  I'd like to recommend that you
make the RS-232 type cable then buy a "NULL MODEM FEMALE-FEMALE"
type connector.  It'll be an extra $10, but you'll end up with a
more versatile set-up.  You could really make both types of cables
cheaper then you could buy a NULL connector, but it's up to you.
I've tested the RS-232 cable with a Supra 2400, Avatex 1200, ST,
and clone, they all work.  The joystick NULL cable works with the
clone & ST.  For some files it well be necessary to print them to
disk on the 8-bit before the ST or IBM can capture them properly.
This is due to different values for carriage return and line feeds
use by the different computers.  For using telecommunication
software with NULL connectors make sure you are not using software
that thinks it's hooked to a Hayes modem unless you have a way to
force it into terminal mode.
Newsgroups: comp.sys.atari.8bit