INT 2F - Windows 3.x (OS/2 2.x???) - GET VIRTUAL DEVICE DRIVER (VDD) CAPABLTIES
AX = 4000h
Return: AL = 01h does not virtualize video access
02h virtualizes the video when in text mode
03h virtualizes the video when in text mode or single plane
graphics modes
04h virtualizes the video when in text mode, single plane
graphics modes, and VGA multiplane modes
FFh virtualizes the video fully
Note:   this function is used by display drivers to find out what capabilities
exist for the VDD driver and also trigger then VDD driver to call
functions 4005h and 4006h.  This function also gives the Video Driver
hardware access to the video registers.


2F4000 - Windows 3.x (OS/2 2.x???) - GET VIRTUAL DEVICE DRIVER (VDD) CAPABLTIES