Doom and VS Link Cables

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Doom and VS Link Cables

Post#1 » Fri Feb 16, 2018 6:45 am

Would it be possible to play any Doom ports for the Dreamcast using a VS Link Cable? The DC's Link Cables are basically null modem cables after all. (Null-modems are cables which link one serial port to another serial port with matching inputs and outputs.)

Doom's README.txt wrote:MODEM PLAY
When you want to play a modem or null-modem game, you need to run SERSETUP.EXE which is the device driver for DOOM's serial communications mode. The parameters are as follows:

-DIAL tells the program which number to dial, if you're going to do the calling.

-ANSWER puts your modem into Answer mode so someone can call you and play DOOM.

-COM1, -COM2, -COM3, -COM4 specifies which COM port your modem or serial cable is connected to. Very important!

-8250 tells SERSETUP to set the UART to 8250. Just in case your 16550 UART is acting up at the higher speed.

-IRQ sets the IRQ for the COM port.

-PORT sets the COM I/O port that SERSETUP uses to communicate with your modem. To use hexadecimal, such as the number 0x3f8, you would type "-port 0x3f8".

-<#> sets the baud rate of your COM port, overriding the value in the MODEM.CFG if you're running a modem game. Legal values are 9600, 14400, 38400, 57600.
Example: -14400

Note that to run a null-modem game, you must have a null-modem cable plugged into a serial port on both computers and each computer runs SERSETUP.EXE with a -COM# parameter as well as any General Parameters. Do not use the -ANSWER or -DIAL parameters, or SERSETUP will think you're using a modem. To get a null-modem cable, go to CompUSA or Radio Shack and say,"I need a null-modem cable to run a DOOM multiplayer game."

You will need to run the SETUP program and select Choose Modem from the Network/Modem/Serial menu so you can set your modem init string correctly. Merely select the modem and press Enter and SETUP will create a new MODEM.CFG file that corresponds to your modem (the MODEM.CFG file is used by SERSETUP for initing the modem.)

If your modem is not in the list, you will most likely need toedit the MODEM.CFG file in the DOOM directory. The first lineof the file is an initialization string that:
* Turns off error-correction
* Turns off data-compression
The MODEM.CFG file has a Hayes-standard init string like this:
AT Z S=46 &Q0 &D0
You just add your own commands after the "AT Z " if your modemdoesn't work with these settings -- dig up your modem manual forthe correct settings.

The second line is a hangup string used when you quit DOOM.

The third line is the baud rate at which you want your COM port set.
The legal settings are: 9600, 14400, 38400, 57600.

If the modem connection isn't working when you call your friend, have him call you instead. Try setting the modem to GENERIC (in the SETUP.EXE program) if your modems don't connect.

If you STILL can't get the modems to connect, both of you should run your favorite COMM programs and connect with 9600, no error correction and no data compression. Then quit the COMM program and keep the connection going. Then just run SERSETUP with a -COM# parameter (as if you were running a null-modem game) since you're already connected.

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