The IOS loads device drivers using the services of the VxD loader device, VXDLDR. The configuration manager directs the IOS to load given port and miniport drivers. The IOS automatically loads any "valued-added" drivers, such a the volume tracker and vendor-supplied drivers. In all cases, the files for these drivers must be in the SYSTEM\IOSUBSYS durectory.
Note
Some drivers are loaded by making specific entries in the SYSTEM.INI file.