INT 21 - DOS 1+ - SEQUENTIAL READ FROM FCB FILE
        AH = 14h
        DS:DX -> opened FCB (see AH=0Fh)
Return: AL = status
            00h successful
            01h end of file (no data)
            02h segment wrap in DTA
            03h end of file, partial record read
        [DTA] = record read from file
Notes:  reads a record of the size specified in the FCB beginning at the
          current file position, then updates the current block and current
          record fields in the FCB
        if a partial record was read, it is zero-padded to the full size
        not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=15h,AH=1Ah,AH=3Fh,INT 2F/AX=1108h