Thursday, May 05, 2005

I've got a question about a Registry value...

The other day, on one of the lists I am subscribed to, someone raised an interesting point. This issue addresses the following Registry key:


Beneath this key are subkeys that are specific to IDE drives on the system. Similar to the USB storage device key, this key has device instance ID subkeys, and beneath each of those are unique instance ID subkeys. Each of these unique ID subkeys has a Registry value called "UINumber".

Now, the issue that was brought up was this...when Windows XP is installed on a system, it looks for other drives that have operating systems installed and assigns the UINumber value accordingly. Therefore, if the UINumber value for a drive is other than 0, that should indicate that XP was installed on a system with other operating systems...right?

The poster stated that he had done testing that demonstrated this assumption. What I'm looking for is any documentation regarding how the value is set. Yes, I've done some exhaustive searches on Google and at the MS site, and haven't found anything that addresses how the UINumber value is set for hard drives.

Anyone got anything?


Anonymous said...


Specifies a number associated with the device that can be displayed in the user interface.
This number is typically a user-perceived slot number, such as a number printed next to the slot on the board, or some other number that makes locating the physical device easier for the user. For buses with no such convention, or when the UINumber is unknown, the bus driver leaves this member at its default value of 0xFFFFFFFF.

Keydet89 said...

Thanks, I'd found that before, while I was researching the USB-connected removeable storage devices. However, it doesn't explain the numbering convention...