I have a device with no internal COM ports. When I add my first COM device it claims COM3 rather than COM1 even though HKLM\SYSTEM\CurrentControlSet\Control\COM Name Arbiter\ComDB has a value of 0, and HKLM\SYSTEM\CurrentControlSet\Control\COM Name Arbiter\Devices is empty.
I’d like to claim COM ports starting at COM1 in this case. What’s the recommended way to do such a thing?
I don’t think the system arbiter will ever assign COM1 and COM2, because of that eternal albatross, backward compatibility. Your LPC chip still supports them, even if they aren’t wired. However, once your device is created, you should be able to go into Device Manager and change its name.
Correct. There is logic in the ports class installer that will only hand out COM names Com1 and COM2 to built in ISA com ports (based on device assigned HW resources or ACPI defined device names). in addition to using the device manager UI, you can call into the ComDB to force claim COM1 or COM2.
(moved to appropriate forum)
backwards compatibility is a very important thing – even when it seems to get in the way