INT 67H 44xxH: Map Memory into Page Frame

                                                     Compatibility: EMS 3.2+ 
 Expects: AH    44H
          AL    physical page number (0 to n; usually 0 to 3)
          BX    logical page number to map in or ffffH (see below)
          DX    EMM Handle
 Returns: AH    EMM status (0=successful)
    Info: This moves the data associated with a particular 16K page of EMS
          memory into the physical frame (making that memory accessible).

          For instance, assuming that the page frame starts at d000:0, then
          calling this with AX=4401H will put the BXth page of your
          allocation into d000:0400.

       BX is the desired page of EMS memory.  It can range from 0 to n-1,
          where n is the size of the allocation (as used in INT 67H 4300H).

          With EMS spec 4.0, you can set BX=ffffH to unmap a 16K portion of
          the EMS frame.  For instance, if AX=4401H and BX=ffffH, then the
          data from EmsSeg:0400 through EmsSeg:07ff will be locked into
          place and cannot be read or written.  To remap a page, use the
          same parameters, specifying a valid logical page number in BX.

   Notes: You may remap only one 16K page at a time with this fn.  You may
          prefer INT 67H 50xxH to map multiple pages.

See Also: INT 67H: EMM Services
          Extended Memory Specification (XMS)
          Interrupts and BIOS Services