Virtual Device Drivers

OS/2 Version 2.0 makes use of two distinct types of device drivers to communicate between the operating system and hardware devices:

  • Physical device drivers communicate directly with hardware devices

    They operate in protected mode, and are accessed by protected mode processes and by virtual device drivers.

  • Virtual device drivers (VDD) do not communicate directly with hardware devices; instead, they provide a virtual device driver interface for DOS applications running in virtual DOS machines

    Some VDDs have an associated physical device driver to which they pass requests. VDDs are 32-bit device drivers and make it possible for devices to be shared between processes running in virtual DOS machines and OS/2 screen groups.

    See OS/2 Version 2.0 - Volume 2: DOS and Windows Environment for a complete discussion of OS/2 Version 2.0 virtual device drivers.

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