• Please review our updated Terms and Rules here

Using an Old Modem to Communicate with Modern Computer

ziloo said:
Thank you Mike!!

I am very interested to find out whether having two different
communication softwares on two ends would work flawlessly. On the
other hand, if it would be necessary to have the same communication
software on both ends where one system is under DOS/Win and another
system is under, let's say cp/m, then one alternative might be a
communication software such as Kermit. I am throwing this to get a
feedback from much more experienced comrades. I have been thinking
along the same ideas for doing serial communication between a PC and
a vintage computer. What are the alternative comm softwares?

Thank you

ziloo
Click to expand...


The bottom line is the way the bits are sent over the wire:

  • Speed, or bits per second
  • Even or odd parity
  • Number of data bits
  • Number of stop bits
  • Character set being exchanged (Usually ASCII, sometimes PETSCII for Commodore folks, sometimes EBCDIC for IBM mainframe)

If you get the basic parameters correct then two different systems can communicate. In ye olden days one often dialed a BBS that was running on a different system.

At a higher level the two systems have to agree on control characters for managing how the screen looks, or on a protocol for file transfer like Xmodem.
 
ziloo said:
Hello Bill,

I am curious as to why you can't eliminate the modems; would you please explain that?

ziloo
Click to expand...

Certain (very few thankfully) systems don't have ANY external ports, the TI CC-40 being one of them. A Hex-Bus wafer drive was planned, but never produced due to reliability issues. The system went away before TI bothered to create a Hex-bus cassette or alternative interface. All that's readily available is a Hex-Bus modem, which is the primary reason for me asking. There are a few other systems that are in a somewhat similar situation. The idea is to sort of use the modem communication as a virtual drive, since Hyperterminal is used as such with the modern-day Micro-KIM, as one example...
 
May not be the same thing, but back in the 90s I had connected two 486 boxes in the same room together via modems for the purpose of playing some multiplater games with my friends.

I used a RJ11 y-jack / splitter. I did it like this. I'd plug the computers in to the splitter, then plug the splitter in to the wall. I think I either used a terminal program (like quick link III or maybe seripx) and simultaniously gave the command ATDT on one machine and ATZ on the other? That second one could be wrong as its been .... well I havent used modem since 1996. But the second command is to tell the modem to Pick Up the line. Anyway the modems would start thier song and I would pull the splitter out of the wall and the systems would stay connected and as a bonus.. freeing up the phone line.
 
JDT said:
May not be the same thing, but back in the 90s I had connected two 486 boxes in the same room together via modems for the purpose of playing some multiplater games with my friends.

I used a RJ11 y-jack / splitter. I did it like this. I'd plug the computers in to the splitter, then plug the splitter in to the wall. I think I either used a terminal program (like quick link III or maybe seripx) and simultaniously gave the command ATDT on one machine and ATZ on the other? That second one could be wrong as its been .... well I havent used modem since 1996. But the second command is to tell the modem to Pick Up the line. Anyway the modems would start thier song and I would pull the splitter out of the wall and the systems would stay connected and as a bonus.. freeing up the phone line.
Click to expand...

Hmm, great idea! I could kick myself for not thinking of that. That would provide the current necessary and I have plenty of those splitters. I assume I could leave it plugged in too.

I hope I have the energy to try it tonight... I want to see if I get it working with some test systems before I bother buying a Hexbus modem for the CC-40...
 
Great,
Let me know how it works for you.
I was younger (12-14?) and had no money, in fact LAN wasnt really a household technology at the time, so instead of buying NICs and a hub, this was a cheap solution that worked fine for the needs I had.
 
Bill,

I've been doing some more digging - the line simulator may not be necessary.

People have been writing that they have been able to do it without a live phone line or a simulated line. I think the correct answer is 'it depends'. A directly connected modem is probably injecting enough current onto the line to make it work, and thus not need the line simulator.

The a line simulator if you want to be absolutely perfectly safe. Otherwise, just try it when you need it and see what happens.
 
mbbrutman said:
Bill,

I've been doing some more digging - the line simulator may not be necessary.

People have been writing that they have been able to do it without a live phone line or a simulated line. I think the correct answer is 'it depends'. A directly connected modem is probably injecting enough current onto the line to make it work, and thus not need the line simulator.

The a line simulator if you want to be absolutely perfectly safe. Otherwise, just try it when you need it and see what happens.
Click to expand...

I'm going to want to try two very different systems, running two different comm programs with two different modems (and max speeds) as the first test, since it wouldn't be terribly beneficial to have same/same (since there's no issue in connecting those or most other systems through normal means). Since I already have it out and hooked up, I may use a C-128DCR and either my desktop PC running Windows XP or my Tablet PC running Vista. I'll try direct connection first, then see if I have to try a splitter at the phone jack.
 
I just scored a whole bucketful of rj-11 wires from the old network at Domino's, so I'm ready to hook a few machines up! I actually have one modem that powers the line, hopefully enough for more than two machines.

Nathan
 
You must log in or register to reply here.
Back
Top