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.

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INT 67H 44xxH: Map Memory into Page Frame