INT 67H 4100H: Get Frame Segment Address

 Expects: AX    4100H
 Returns: AH    EMM status (0=successful)
          BX    segment of EMS frame
    Info: Obtains the segment at which the EMS frame is mapped.

          The EMS frame is a 64K area, often starting at d000:0.  Depending
          upon switches used when the driver is installed, the frame may
          actually start at any segment address from 8000H to 9000H (seen
          rarely) and c000H through e000H in increments of 400H.

          When you read or write to EMS memory, you will use INT 67H 4000H
          to map part of the EMS into this frame, then read or write to the
          64K starting at the segment returned in BX.

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