DPMI MapPhysicalMemory Function 0800h

I am trying to find a workaround for the apparent inability of Windows XP to support the DPMI function call 0800h.

This function is used when attempting to create the Linear Frame Buffer, used to access the entire array of video memory on a video display card, such as an nVIDIA 7300GS.

I have been researching on the net, but have as yet to find a method of getting XP to allow this to work, and am hoping not to have to go thru reinventing the wheel.

I have Turbo Pascal, C/C++ and Forth libraries that all show the same problem, as well as numerous demo programs that are unable to enter the VESA resolutions that require the LFB.

Has anyone seen an answer to this problem?

TIA