Function 2Fh (47)        Get Disk Transfer Address (DTA)

    Gets the current DTA (Disk Transfer Address).

       On entry:      AH         2Fh

       Returns:       ES:BX      Address of current DTA

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       Notes:         If Function 1Ah (Set Disk Transfer Address) is not
                      used to explicitly set the DTA, a default DTA of 128
                      bytes in length at offset 80h in the PSP is
                      automatically established by DOS.