It's interesting. Some of our tests involve swapping the devices to different USB ports on the computer. Some devices, new COM ports are created when I swap to a different USB port, and other devices, they keep the same COM port number when I swap.

What's funny is that I've got some USB GPS units which are made by Pharos but which are microsoft-branded. We've got both sets here: The original Pharos units as well as the Microsoft-rebranded ones. The MS ones have a slightly different USB ID and run on different drivers, but the hardware is identical, right down to every detail on the packaging and labeling. They both use a Prolific chipset for USB-to-serial conversion. The Microsoft ones are the ones that stay the same but the Pharos ones make a new COM port when I swap.