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So I have a very, very old DOS machine with an RS232 port on it and I want to be able to transfer files to it from a Windows 7 machine. For this i bought an RS232 to USB cable.

What sort of software do I need for the devices to see each other, once i get the cable plugged in?

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Is your RS232->USB adapter a NULL Modem cable? If not, then you need to go get one. :) – Ƭᴇcʜιᴇ007 May 24 '13 at 19:41
Should've gotten a NIC instead... – Ignacio Vazquez-Abrams May 25 '13 at 3:37

What you're asking for is not exactly straight forward. Even when connecting two computers with both ends being USB it typically requires a bridge component to facilitate file transfer. [1]

Likely, you would need some kind of terminal program or something on the DOS machine to tell it to push data out through the RS232 serial cable and another program on the Win7 side to receive it.

You would likely have a much easier time plugging your DOS machine in with ethernet and doing a simple file transfer. (Assuming it has an ethernet port, though I haven't seen too many DOS machines without one)

MS-DOS 3.1 was the first DOS version to support networking and file sharing. To share files you would use the SHARE program.

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My original thought was with Ethernet as well... unfortunately i never could get that to work. The two computers simply never could see each other. – Capurnicus May 24 '13 at 18:59
Are you able to get an IP address on the DOS machine? Are you able to ping the default router/Windows 7 PC? If not, is there a firewall or rules preventing you from doing so? You should be able to access your Win7 from DOS using "net use Z: \\WIN7NAME\C$ /User:username password" – Will.Beninger May 24 '13 at 19:03
I figured out how to set the DOS machines IP Address yea. Using a crossover cable i connected it to my Windows 7 computer. I set Z: to equal exactly what you put.... The DOS machine never showed the Z: though in the Router Program (which i think is the problem) that it boots into. – Capurnicus May 24 '13 at 19:07
@Capurnicus: The problem you are facing is probably this: From Windows Vista onwards NTLMv2 is used for authentication. Older OS's cannot handle this, hence you cannot connect to your W7 shares. It is possible to tell W7 to use the old NTML authentication. Please see the TROUBLESHOOTING/SECURITY section of this document: – mpy May 24 '13 at 19:39
@Will.Beninger: Which DOS version ships with net? I thought this was a feature of WfW 3.11? – mpy May 24 '13 at 19:40

My goto application for this sort of activity was kermit. Other alternatives are xmodem or ymodem. Most terminal programs should support one or more of these.

kermit is quite scriptable and works over 7bit and 8bit connections.

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You might try PuTTY, which can connect via a serial connection:

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