Com ports issue ?

[merlin]

Hi People, I really could use some help here with vDos serial ports.
 I am running a specialized Dos program that communicates with a device.
This is a Windows 10 Dell computer and the only ports available are port 3 and 4. Not an option. (com 4 is preferred)
I have read through many of similar threads for a solution.
Here is where the issue is. No matter what I have tried, I get an error the com port cannot be opened and that causes the Dos program to exit.
Changing com port setting in Widows looks like that is working, still fails running the app.
This has to be changed back for several other apps that use com 4.
Is there anything in vDos that can be done to get port 4 to work ?
TYIA
Merlin

[Jos]

You have COM4="Windows_device": in config.txt? So vDos will not treat COM4 as a print destination, but mimic serial operation with status registers.

And checked the Windows_device settings with MODE at the Windows command prompt before starting vDos?

Then still the DOS program could not be satisfied. For instance if it relies on interrupt driven communication. That is COM4 generating an interrupt to indicate data arrived or can be send. If there’s an option to disable using interrupts, try that.

Jos

[jamesb52]

A simple work-around is to send output to a text file instead of to a DOS device like COM or LPT. You can then print the textfile to a Windows printer with Notepad. If you're lucky, your DOS app will offer that option. I personally like having all output saved forever. It's really useful!

[Jos]

The question was not about printing, but a program using COM4 to flash a 80C52 chip.

Jos