I have a VB6 application running on a number of old 486 Windows 95 machines and sometimes the application is upgraded. The only way to accomplish this today is to use Hyperterminal and send the file over a null modem cable. Replacing the machines is not an option at this point.
I want to write an application that can take care of transferring the updating app over null modem without rewriting the VB6 app. This means I'm free to use anything I see fit. What alternatives are there?
These are the ones I can think of but I'd like to know if I'm wrong and any pros/cons. Also, I'd prefer to avoid C/C++ if at all possible.
Edit: Some clarifications after reading the comments:
I want to make the process as easy as possible, today we have to remove and dismantle the computer, connect a keyboard and then fire up Hyperterminal to get going. That's why I want something more automatic. I'm open to suggestion of existing solutions but given the specific needs I didn't think there were any.
There is no ethernet on some of the computers either so the solution needs to be able to run RS232.
And again: Replacing the machines is not an option at this point. Just trust me on this.
I would first get network cards installed in everything. If you want something that you can just plugin and go, look for any card compatible with NE2000. That card will work out of the box on Windows 3.11 and 95, no problem. In particular, you can find the 3Com EtherLink II or the 3C509B for very cheap online. It's an excellent card. (The Google Shopping results list several for under $20.)
From there, just enable the Windows File/Print Sharing service over TCP/IP, and you're good to go! After you've done this, you can remotely manage and upgrade these machines, saving you a lot of headache later on.
Deanna's suggestion of using the serial port as a network device and transferring files normally will work as well. However, there is a bit of setup involved, and it can be a hassle if you've never done it. There are several other software options. I recommend LapLink. It's fairly painless.
You could even go all-out and pickup a multi-port serial interface for fairly cheap these days, and manage these computers centrally. RS232 is very robust and can go a long distance over the proper cabling.
Networking over Ethernet is the way to go though. If at all possible, choose that option.