Microsoft OS Descriptors

Updated: April 11, 2014

USB devices store standard descriptors in firmware for the device, and its interfaces and endpoints. Independent hardware vendors (IHVs) can also store class and vendor-specific descriptors. However, the types of information that these descriptors can contain is limited. IHVs typically must use Windows Update or media such as a CD to provide their users with a variety of device-specific information such as pictures, icons, custom drivers and so on.

To help IHVs address this issue, Microsoft has defined Microsoft OS descriptors. These descriptors can be used by IHVs to store in firmware much of the information that is now typically provided to customers separately. Versions of Windows that are aware of Microsoft OS descriptors use control requests to retrieve the information, and use it to install and configure the device without requiring any user interaction. This white paper provides an introduction to Microsoft OS descriptors, including a discussion of how they are stored and retrieved.

Note: The table of compatible and sub-compatible IDs in Appendix 1 of "Extended Compat ID OS Feature Descriptor Specification" is current as of the time the specification was written, but might have since changed. The following table contains the most recent list of compatible and sub-compatible IDs. All IDs must be eight bytes, so any unused characters are filled with NULLs.

CompatibleID

Sub-compatible ID

Description