virtualbox.org

Dear VirtualBox community,
Recently I installed Windows XP inside of a host XP in order to run some old software that refused to work with SP3.

The software uses a COM port, which attaches to an IR tower, to program a small external computer (called an RCX). This setup seemed to send and receive fine, however the small computer did not seem to understand what the IR tower was transmitting. I used another piece of software in the guest, which is compatible with SP3, and found again that the IR tower didn't transmit properly. When I tried said program on the host, it transmitted fine and the RCX understood.

I was wondering, how exactly does VirtualBox handle COM communication? Is there a way to hand complete control of a COM port to the guest?

Best Regards,
Paul

My experience with Com ports is they can not handle more than 9600 baud using VBox. Any more and it appears to garble the data.
As far as a direct connection to the hardware from the guest it can not be done, at least as far as I know with any virtualizer.

Ah interesting. I've looked up the specs and it transmits at a 2400 baud rate, definitely quite old. However, it handles the COM port in quite a custom way. However in both the host and guest, the device settings are set to 9600. I wonder if it might be that the host is transmitting at the wrong rate? I will experiment later.

Are there any developers about to answer how virtualbox handles COM ports?