USB to RS232 adapters are very unreliable; generally onboard serial ports or PCI serial cards are the way to go. If you still have a Win9x machine kicking around I would suggest first verifying that the USB to RS232 adapter works with your Cyberman there.

Thanks, I will ignore all USB to RS232 adaptors.

Does anyone have a recommendation for a windows 10 compatible RS232 card that I could buy to work with Dosbox? (I still have not given up hope for using my Cyberman.)

You should be warned that even with a PCI RS232 card you still might not get this item working in DOSBox, but you'd definitely have better chances than with a USB to RS232 adapter.

Looks like Newegg has one at http://www.newegg.com/Product/Product.aspx?It … 4-104-_-Product , but I don't have experience with that one myself, and I doubt you'll find anyone here who does have such experience. There are a lot of people who pass through looking for help getting their serial devices working, but they rarely come back to provide success stories.