请再指教！

我看了微软的帮助。
How to support a USB mass-storage device on a Windows 98-based computer that is compliant with the Control-Bulk-Interrupt Transport defined by the USB Mass Storage Device Class.
How to create a virtual child object in a WDM driver, and use it to load a separate driver.
How to communicate between a VxD and a WDM driver.

两部分中的pdr应该是一个vxd,我不太了解vxd.
但是我想直接用sys部分，也就是wdm,应该可以读写usb.
比如我看了\"windows wdm 设备驱动程序开发指南\"中的wdm1程序，
这个程序就可以读写，函数为wdm1read和wdm1write。

盼望指教！