Editing Intel Architecture Labs (section)

==== USB host controller design ====
A critical component of the USB design was the interface between hardware and software, which was the domain of the USB Host Controller, the brains behind the interconnect that all USB devices communicate with.  The USB Host Controller was embedded in the South Bridge chip, and was designed to match the USB specification being developed by the IAL engineers.  USB was, like PCI, a unique combination of hardware and software definitions, and as a result the project needed a software engineering team from the outset, unlike typical Intel hardware 
projects. The USB software device driver "stack" was initially developed on Windows 95 using the Virtual Device Driver (VxD) model of Windows 95. The VxD-based USB driver stack was helpful to Microsoft as they implemented a brand new USB stack using the emerging Windows Driver Model (WDM) largely because of Microsoft's strategic shift towards Windows NT, and away from Windows 95.  WDM was uniquely compatible with both operating systems, and the decision to abandon the VxD stack was a win-win for Intel and Microsoft.  The collaboration between IAL and Microsoft improved during the development of USB 1.0, largely driven by the software developers that Intel hired into its IAL labs. Software developers at Microsoft were able to speak a familiar technical language with their fellow software developers from IAL, allowing the group to work as a single unit to drive the USB standard into the Windows-based PCs of the 1990s and beyond.