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Anyone got any info on this modem

J

josephdaniel

Experienced Member
Joined
Jul 3, 2012
Messages
317
Location
Florence, Texas, United States
I have a modem that I *think* I pulled out of my XT when I got it. Anyways does anyone know what com it needs to be on in order to function? And does anyone have any information about what speed this modem is and the model? I was hoping to use lync to transfer files between two computer mostly just for fun.
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COM port depends on what COM ports your machine already has.

If it has COM1 COM2 and COM3, then set it to COM4 (just don't use COM2 and COM4 at the same time).
If it has COM1 and COM2, then set it to COM3 (just don't use COM1 and COM3 at the same time).
If it has COM1, then set it to COM2

Rockwell 14400 baud? I'm curious about that EPROM, that's not normal.
 
josephdaniel said:
Is there any way to tell which com port is already used? If you want a image of the eprom I can try to get it but I don't know the debug commands
Click to expand...

DISABLE ALL your onboard ports, then plug this one in... MSD will then tell you what port/IRQ it is on...
 
josephdaniel said:
and what's unusual about the eprom?
Click to expand...

EPROM's are usually added to expansion cards to add software that can be run before the operating system. e.g. used on SCSI cards to boot from SCSI drives, or network cards to boot off the network etc.
I just haven't seen one on a modem before!

For serial ports I just use a program like MSD (part of MS DOS 6) or Checkit or even FastLynx 2 but I'm not sure what you have on hand. The other guys here might know some DOS tricks.
Generally though, if you see two serial ports on the back of the machine, they're probably COM1 and COM2.
 
The modem has a very nice label next to the switch block telling how it is setup. In the picture, the modem is set for COM1.
 
Don't get excited. The EPROM is probably for the modem firmware, not a BIOS extension. Or in other words, only the modem can see it ...
 
mbbrutman said:
Don't get excited. The EPROM is probably for the modem firmware, not a BIOS extension. Or in other words, only the modem can see it ...
Click to expand...

Yeah, it's the firmware for that Winbond microcontroller next to it. With a number like "W78C31" I wouldn't be surprised if it's an 8031 derivative.
 
As long as you get it working on the right com port it should work. Without the card installed, run MSD or portfinder (if it is still around) and see what com ports are configured. Turn the machine off, set the modem to a COM port that isn't configured, plug it in and re-run MSD and see if the modem is identified.

A little note about com ports in the PC/XT class machines. They typically share an interrup. COM1 and COM3 share IRQ4. COM 2 and COM4 share IRQ3. See http://webpages.charter.net/danrollins/techhelp/0096.HTM for some clarification of IRQs in XTs. For 8 bit machines, IRQ7 is the last one. 9 through 16 are on AT and higher machines.
 
It could have come out of an XT but it was uncommon to see an XT get upgrades in 1993 or so when the card was made. It should work with an XT. PC-DOS 2.1 would be more an issue as to whether any communications software would work with both 14,400 modem and DOS 2.1. I suspect that the modem would work in that configuration but you might only get 2400 baud through it because of the very old communications software needed.
 
with it unplugged, boot up and do this:

echo "foo" > COM1:

Does the system return to a prompt or lock up?

If it locks up, configure the modem for COM1, put it in, and repeat the test - if it returns to a prompt, you're golden on COM1:. If the echo command returned to a prompt, repeat for COM2:... if the system locks up, configure the modem for COM2: and insert it and repeat the test on COM2:, it should return to a prompt.

Then fire up your term software, configure it to use whichever COM the modem is set to, and get busy.
 
Also, for clarity, "lock up" could include dos messages about devices not being ready, or such... Been a long time since I tried that method, but it's viable...
 
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