It is possible to connect two computers together and play network games
through their serial ports. (Com ports) This type of connection is
known as a null-modem connection. This type of link communicates in a similar
fashion as a modem but does not actually use the modem to negotiate the hookup.
This type of connection also allows much faster data communication than a
modem normally yields.
I have spent many hours trying to gather the information on how to make
this work. Of course nearly every game with multiplayer abilities says
just plug in a cable, run setup, and voila! Well I tried that and it didn't
work. Their documentation stops there. If at first you didn't succeed,
good luck doing it later.
Included is a small batch file that I have created. This program
contains basically the same information that can be found on this page.
This file is compressed. Null.zip (4K)
On most computers there are two serial ports, com1 and com2. Generally
one port is wider than the other. Ports can be 25 pin or 9 pin ports. It
makes no difference which is used.
As with any other system device, your com port uses system resources.
For example, IRQ 3, Memory range 03f8. One very possible conflict is that
your modem is already using the resource that your com port is demanding.
In order to defeat this you can do one of several things.
Physically remove your modem
When you power on your computer, your BIOS asks your modem what resources
it wants to use. If it demands port 1 and you try to use one for another
purpose, it can't have it, no vacancy with that resource. By removing
your modem, that resource is never requested and thus is free. This may
be a less desirable solution especially if you value easy use of your modem.
Change your modem to another port setting
You can manually change your modem to use another port. Though you have
two ports in the back of your computer, you have potentially available 4
ports. Port 2 and 4 would be the same plug on your computer, but only one
would use the resources at the same time. The same for 1 and 3. If you have
a modem on 4, and connection on 2, both will work but NOT at the same time.
Doing this requires changing the jumper settings on your modem. You must
set them for the port and IRQ. To do this correctly you need to consult
your hardware documentation or it is possible printed on the side of your
modem.
Use another port for null-modem
*duh*
*Be sure the ports are enabled in your BIOS. One of the last problem that I found I had was that com2, which I was trying
to use, was disabled in my BIOS. I enabled that but then my modem conflicted.
After I changed my modem to com4, I was able to make the connection work.
...That was then. Now on my newer computer, I can't get the null
modem game to work at all if
my modem is plugged in to my board. Arrrg! Not only that, but I can't get
my modem to work on any port but 1 if port 2 is not disabled in BIOS.
Does this seem stupid? Can somebody design this better?
If you have to adjust your BIOS settings, which you may, you will probably have
to do some trial and error until you get things right. The following page,
More about com ports (text only) explains a little about
serial ports and
tells how I had mine set up to work.
Be sure to have the correct type of cable
Another one of my hardest problems was getting the correct cable. No
offense intended to Radio Shack (any other store) but I warn you
about going in to Radio Shack and asking the clerk for a "serial cable" and
a "null-modem adapter." I did this and I bought the wrong stuff on more
than one occasion at more than one store location. Find out what you need
and get it yourself. Half of those guys are morons on commission who will
say "sure" regardless of the correct answer.
Or make your own cable...
The best solution in my opinion if you are capable of doing so is to
make your own cable. That is what I did and I was highly successful. The
job can be done for $15 dollars in parts and a soldering iron. The yield
is a 25 foot cable. Much better value than you are likely to buy one
of equal length for.
I purchased the ends (about two dollars each) and a 50 foot spool
of telephone cable. (4 wires) Cut the phone line in half. Now you
will have 8 wires. This is all you will need. Now solder. You have
the option of wiring it pin-to-pin like a standard serial cable and then
putting an adapter on it, or do like I did, wire it null-modem in the first
place. (switch the wires yourself) Now twist the wires so that the wires
don't hang all over the place and tape them incrementally and you have a nice
cable. Visit Serial Ports
to find out what pins you need to switch.
I
decided 25 feet was too short so I made another and wired it straight
through to be my extension. Now 50 feet makes it darn near everywhere in
the house and works fine. Use your own judgement here. I have read that serial
cables and parallel cables are not intended for use over 20 feet and after
that become less reliable. I have yet had no trouble. Perhaps phone
wires have less resistance. (or else they were wrong) *shrug*
Disclaimer: This is a report of my findings only. If you wish to
follow a path similar to mine, that is fine and that is your free decision.
Do not expect me to take responsibility for any of your actions regardless if the
consequences are good or bad.
