• Please review our updated Terms and Rules here

Can’t get direct cable connection to work

3lectr1c

3lectr1c

Veteran Member
Joined
Nov 28, 2022
Messages
1,256
Location
USA
Trying to connect two thinkpads together and they just won’t find each other. Parallel cable is plugged in to both.
Host is Windows Me, guest is 95 OSR 2.5
D6A8A407-EBD1-4F8A-AB1D-8081A59D9284.jpeg
Any ideas?
 
Long shot here, but have you checked the BIOS settings to see if there are any related to the parallel port?

Dave
 
Host machine (thinkpad i1260) had the following options:
D6AA6993-D402-4E03-B529-D78EC0963B81.jpeg
Guest machine (thinkpad 560) doesn’t have anything parallel related it seems.
 
Just tried to connect as a guest through my ThinkPad T30 (win 98) and it won't either. Means that the issue is with the i1260 or I've configured something wrong. First time using DCC, watched a tutorial on it.
 
Cable is a generic db25 cable. Could be the issue? I bought it to use as a scsi cable so it could be missing conductors, but it is a generic with no markings either way. It works for scsi. Don’t know what laplink is I’m afraid.
 
Yeah you can't use a straight through cable. You need a laplink/interlink cable.
 
That would make sense. I'll look into getting one. Thanks folks!
 
Last edited:
I've owned Laplink since about 1988. It is a software program by Traveling Software to help transfer files between two computers easy enough for a non-techie. The idea was for office folks who traveled with their laptop to be able to connect the laptop to their work station desktop at the office and transfer files back and forth to synchronize their data. Laplink came with two cables, one was for use with the serial ports and one was for use with the parallel ports. Eventually cables that were similarly designed became known a "Laplink Cables". The serial cables are basically a null-modem cable where the transmit and receive signals were physically switched so that a direct communication could easily be setup between the two computers.

You need to use a different cable. A straight thru cable may not work for what you are trying to do. The parallel cable can also be wired for direct communication similar to a null-modem. Sometimes the software can be adjusted to work with a straight thru cable but the software has to support it. Check your cable. Or try the serial ports and a null-modem cable (aka "Laplink cable").

Seaken
 
I've used DCC over a serial cable in the past. Installed Office 95 through it, not recommended. Slow as molasses, but worked reliably...

On a different note: Does anyone have a good description of the DCC serial wire protocol? Since it is part of Windows, it would be a decent way to connect to modern machines if there was a decent client on the other end. Especially since it supports TCP/IP as well.
 
You need a specially wired "Laplink" parallel cable to use DCC over LPT ports. Also the DCC adapter needs a network protocol bound to it in Windows 9x.... NetBEUI does the job just fine.
 
Svenska said:
I've used DCC over a serial cable in the past. Installed Office 95 through it, not recommended. Slow as molasses, but worked reliably...

On a different note: Does anyone have a good description of the DCC serial wire protocol? Since it is part of Windows, it would be a decent way to connect to modern machines if there was a decent client on the other end. Especially since it supports TCP/IP as well.
Click to expand...
At the software level both serial and parallel DCC are just PPP. There's an exchange at the beginning where one side says CLIENT and the other says CLIENTSERVER (don't remember exactly which order) but then they just switch to PPP, so it's something you can handle with a chat script. There are Linux HOWTOs out there walking through how to set it up for serial.

At the hardware level, the serial one is just RS-232 of course, and the parallel one is implemented in Paralink.vxd as a custom protocol where various nibble values are sent to the other side to transition through states of the protocol, and there are checksums implemented. I have a partially working compatible implementation, but still need to flesh out the state machine and such to improve its handling of deadlocks and timeouts and such. It is much faster than 115K serial, however; if I remember right, about 20 KB/s transfers. This is "nibble mode" and works with a LapLink cable, but is very CPU-intensive. The server end has to pace itself with intentional delays to avoid overwhelming the other (vintage) machine. There is also an MTU-like setting to break up transmissions over the parallel cable and sometimes shrinking it actually improves the transfer rate. Digi-Key still sells LapLink cables, by the way.

Paralink.vxd was outsourced to Parallel Technologies (PTI) which I remember from early 2000s as they offered as freeware a replacement paralink.vxd and an enhanced diagnostic utility. They also sold an intelligent parallel cable (but I've never been able to find one) that buffered both sides and spoke ECP or EPP to each end of the connection and relayed it to the other machine, so as to be faster and not CPU intensive.
 
I remember having problems with DCC on some computers. Sometimes it would work perfectly, sometimes it would just disconnect randomly, on 2 identical computers. Never understood what was wrong, maybe some extra stuff to config in Windows.
 
Well, I think I do know the problem, I'm missing the lap link cable. I've looked on ebay but I'm having a hard time finding the proper one. Also, does any laplink software exist for DOS or Windows 3.1?
 
Yes, Laplink 5 for DOS or Laplink 6 for Win 3.1. (LL 7 for Win95)
You can build cable easy, check on internet laplink serial cable pinout and create one.
 
That's pretty darn cheap. Might have to pick one of those up soon if they'll finally solve my seemingly endless file transfer issues between my PCs. One issue I do see is this - my duo of WinBook laptops both have dead floppy drives so I can't get files on or off of them. The keyboard connectors are also fragile enough that I really don't want to risk it and take the hard drives out to get stuff on to them. Is there anything built into Windows 3.1 that could help to get DCC working?
 
You must log in or register to reply here.
Back
Top