andreja6 wrote:

Are there any program to transfer files over a Null Modem connection?
I've heard of this being done but I can't find any DOS compatible programs to do this

Are you doing a transfer from one DOS machine to another DOS machine or ? There is a program included in MS-DOS 6.x called interlnk that will handle that no problem. I'm near positive it will not work from serial to usb for a modern machine though, we'll have to look at alternate solutions for that, I use an ISA ethernet card for transfers with modern PCs or you may find an IDE to Compact Flash card to be the easiest way.

Im trying to do transfer from either a 98 machine to a DOS machine or a 7 machine to a DOS machine

andreja6 wrote:

Im trying to do transfer from either a 98 machine to a DOS machine or a 7 machine to a DOS machine

Hmm and it absolutely must be over a null modem? I use an ISA Ethernet (3com etherlink III) I got from ebay for $5 to make life easier with transfers to modern machines, and even that was a little stressful to get working.

It should be doable on the windows 98 PC, as I've played DOOM over a null modem that way many times.
A quick search brings this up: http://www.pcxt-micro.com/dos-interlink.html -- I wouldn't take his advice and replace your autoexec.bat and config.sys though, just take a look at the lines included in his download folder and you should get the idea, looks like he set is up to use LPT:2. But you should see how it's done there. It should be very easy to set up assuming you have a laplink or nullmodem cable.. I use a DB9f to DB9f serial null modem cable I got from ebay for ~$5 for playing doom.

I'm guessing your win 7 machine has no serial or parallel ports? If not I'm thinking some parallel to ethernet adapter could be had to do this, otherwise isa ethernet card with tcp/ip drivers and the "net use" command or just a plain FTP server are the usual methods to do this.

andreja6 wrote:

Are there any program to transfer files over a Null Modem connection?
I've heard of this being done but I can't find any DOS compatible programs to do this

Hi! I know of Ultrafast Filetransfer Operation, which was made by Upward Systems long ago somewhen in the mid-80s.
A more recent program I know of is File Maven. Version 3 for DOS is Freeware since quite a while.
It can be run inside of DOSBox, too.

https://www.youtube.com/watch?v=rVKqA8B0oV4
https://www.youtube.com/watch?v=LYlL9XILVTs

http://www.briggsoft.com/fmdos.htm

BeginnerGuy wrote:

Hmm and it absolutely must be over a null modem? I use an ISA Ethernet (3com etherlink III) I got from ebay for $5 to make life […]
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andreja6 wrote:

Im trying to do transfer from either a 98 machine to a DOS machine or a 7 machine to a DOS machine

Hmm and it absolutely must be over a null modem? I use an ISA Ethernet (3com etherlink III) I got from ebay for $5 to make life easier with transfers to modern machines, and even that was a little stressful to get working.

It should be doable on the windows 98 PC, as I've played DOOM over a null modem that way many times.
A quick search brings this up: http://www.pcxt-micro.com/dos-interlink.html -- I wouldn't take his advice and replace your autoexec.bat and config.sys though, just take a look at the lines included in his download folder and you should get the idea, looks like he set is up to use LPT:2. But you should see how it's done there. It should be very easy to set up assuming you have a laplink or nullmodem cable.. I use a DB9f to DB9f serial null modem cable I got from ebay for ~$5 for playing doom.

I'm guessing your win 7 machine has no serial or parallel ports? If not I'm thinking some parallel to ethernet adapter could be had to do this, otherwise isa ethernet card with tcp/ip drivers and the "net use" command or just a plain FTP server are the usual methods to do this.

Funny enough, my windows 7 was actually intended as a server machine. All my PC's have serial ports 😀

andreja6 wrote:

Funny enough, my windows 7 was actually intended as a server machine. All my PC's have serial ports 😀

Hmmm, I wonder if you can pass those ports through to a WIN9x virtual machine and just use interlnk/intersvr to get them talking over serial. Obviously the VM or DOSBOX will be needed to run those 16 bit executables, This is not something I've ever attempted before, I wonder if anybody else on the forum can jump in on this. I'm sure it could be done with hypervisor or vmware esxi but that would be quite a bit of effort.

If you can get the null modem working that way, then you can also do null modem games too 🤣 . I have no way to play with this at home though, definitely interested though.

Total Commander also supports parallel port connection, and there should be DOS server available for it as well.

On win9x to win9x i had no luck with direct cable connection features of windows, but i had sucess with HyperTerminal transfering files with ZModem, my guess is that you can receive a file with zmodem on dos aswell.
Beware of the speed limitation(bps = baud * bits per baud), my lte 5300 and my s7 pentium computer can communicate with each other with 57600 baud, for example transfering a duke3d game zipped is WAY slower than turning down the machine, removing the card(currently using cf to ide 44pin adspter), inserting into the card reader on my main computer and copying the game, inserting back into the retro pc and booting it back up.
Even with networking i recommend giving a try with the cf/sd to ide adapter, specially if you manage to get one that reach the back of the computer, some people have problems with it but i tried on 2 different machines and it worked on the first try and didn't presented any issues over the time.

Columbia University's Kermit software may fit the bill. Kermit 95 has a Host Mode that can be used with null modem and other types of connections, and supposedly works with Win9x through Win7. Even if you don't use the Host Mode capability, you should be able to make connections and do file transfers using a number of protocols with Kermit.

(Edit: Kermit 95 isn't free, although there is a 21-day evaluation download. You might check to see if someone has figured out how to use MS-DOS Kermit in a DOS emulator of some sort.)

Info and download links for MS-DOS Kermit:
http://www.columbia.edu/kermit/mskermit.html

Download link for Kermit 95:
http://www.kermitproject.org/current.html

Kermit 95 Host Mode Information:
http://www.columbia.edu/kermit/k95host.html

One thing you probably want to do if you use Kermit or any other protocol and you plan to use a direct null modem connection is set the transfer block size for the maximum allowed. The default block size values in Kermit and other programs tend to be set to small values suitable for telephone modem connections which are inherently noisy. Unfortunately, this means a lot of overhead that is unnecessary when a direct/serial null modem connection is used, and this translates to much longer file transfer times.

Good luck!

Same programs you use to call to BBSes, such as Telix or Telemate. They understand most of the common protocols (archaic such as Kermit and newer such as zmodem).

You will find same protocols being used in windows and linux terminal programs as well. Since hyperterm does not come with Windows any more, get TeraTerm, since it is an open source program.

If you want some more direct file transfer using custom protocols, there were programs such as Laplink or Fastlynx that can be used for that. For mounting DOS partitions directly, DOS 6.22 came with Interlink and server.
These programs not only supported serial, but parallel cables as well for faster file transfer. These were commonly called Laplink cables.

Hi there, I am trying to connect a Toshiba Tecra 730XCDT (Pentium MMX CPU) running DOS 6.22 with a Zenith 433-VL (486 CPU) running DOS 6.20.

I am using a null modem cable (female to female), I've tried to specify /com:1, /noprinter to save a bit of memory, whatever... But it keeps on saying "Connection NOT established", even though INTERSVR.EXE is up. Do both laptops need to run the exact same DOS version?

Thanks in advance!

EDIT: Do I actually need an adapter anyway?

I never had any luck with Intersvr/interlnk. They aren't version specific, I had it working over parallel between my XT running dos 3.2 and my 286 running 6.22. If both computers have a parallel port, I would suggest trying to get a parallel data transfer cable. It will run much faster (trust me, you don't want to transfer anything substantial through a serial port).
Here's a link to a cable.

https://www.ebay.com/itm/oem-PC-ANYWHERE-Para … bMQHJ:rk:2:pf:0

Norton Commander is what I was using for that purpose in the past, without a problem.

LapLink DOS
FastLynx DOS
FileMaven DOS (freeware)

These are the utilities I had used in the past for simple file transfer over serial NULL modem or a much faster LPT2LPT Laplink/FastLynx cable. It depends on how the LPT cable is wired, the data can move at 4-bit or 8-bit chunk. Usually, if the cable says it is cable for LapLink or FastLynx, then it will do 8-bit chunk. This requires both computer to have real ISA/LPC-based COM or LPT ports. PCI or PCI-express addition or USB converter will not work. Nowadays, it is hard to find legacy COM/LPT on new PC or laptop, everything is USB.

If one of the system is 32-bit modern OS (Win2K/XP/Vista/7) and you are adventurous into compiling DOSBox, then you can run DOSBox patched with parallel port and serial port raw IO pass-through. All the 3 utilities above works from the patched DOSBox for file transfer to/from a real DOS machine. This was my favorite file transfer method when I could still find COM/LPT port on Dell/Thinkpad laptops or their supported docking when I worked on embedded software development for DOS machines. Even an old-school full-screen symbolic debugger would work within patched DOSBox over the Laplink parallel port cable to debug the software running on the target DOS machine. It was a simple and clean setup without involving DOS networking or ROM/FLASH emulators, just one LapLink cable between the development WinXP host and DOS target.

Ebox was the mate to the fastlynx series of programs
you could share drives and a printer of a remote dos pc.
I found the floppy last night,trying to recover the files off it.
serial or parallel cable

ebox for drive sharing fat16 dos machines.
parallel/serial cable

I have a similar Question: A great OpenSource solution is ParCP...

PARCP stands for PARallel CoPier. It does copy files between two computers. It acts as a file network running over parallel (=pr […]
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PARCP stands for PARallel CoPier. It does copy files between two computers. It acts as a file network running over parallel (=printer) ports of those computers. This allows you to copy many and large files very quickly from one machine to another, either by simple drag & drop, or automated in batch mode or you can choose from two different user interfaces (command line like in a FTP client and fullscreen windows just like Norton Commander).
...
PARCP has been designed to work on two different computer platforms:
Atari ST/STE/TT/Falcon
from IBM PC 386 up to 64-bit AMD and Intel CPUs

(From Documentation here: https://joy.sophics.cz/parcp/parcpdoc.htm )

There exists binaries for: Apple, Atari, DOS, Linux, Windows and Raspberry Pi

Homepage: https://joy.sophics.cz/parcp/download.htm
Sources: https://github.com/joysfera/parcp

Sadly it's not useable on older XT: https://github.com/joysfera/parcp/issues/4 Maybe it's possible to implement a client, that run on a XT with only 512KB RAM ?!?

Is there is a free, open source solution for XTs?

I find only closed source ones: "Commander Link" from Norton Commander v3 or v4
NTERLNK / INTERSVR from MS-DOS or "filelink" from Open/DR-DOS

Don't know if the freeware "File Maven" will run on a XT wioth 512KB RAM: http://www.briggsoft.com/fmdos.htm

Another question: Were ever the used protocols of the mentioned programs been decoded and or disclosed?

Why don't you use good old XMODEM then?
It works fine with way less than 56KB of RAM, so it should be usable on all but the weakest PCs.

Edit: Back in 1984, on PCs, I liked Crosstalk, it was/is very universal. I think it needs far less than 128KB RAM.