INT 31H 0508H: Map Device in Memory Block

                                         Compatibility: DPMI [optional] 1.0+ 
 Expects: AX    0508H
          ESI   memory block handle (as obtained via INT 31H 0504H)
          EBX   base offset of page(s) to map
          ECX   number of pages
          EDX   physical address of device memory (page-aligned)
 Returns: CF    NC (clear) if successful; else AX = DPMI Error Code
    Info: This maps the physical addresses assigned to a device into the
          linear addresses of a block allocated via INT 31H 0504H.

          This is designed to make it possible to page-out physical memory
          that is ordinarily assigned to a device, such as a video memory
          buffer or a Weitek numeric coprocessor.

See Also: DPMI API
          INT 2fH: Multiplex Interrupt
          DOS Functions