Function 440Eh (68-14)   IOCTL: Get Logical Drive                   . DOS 3.2

    Returns the drive letter used most recently for block devices that
    have more than one logical drive letter.

       On entry:      AH         44h
                      AL         0Eh
                      BL         Drive number (0=default, 1=A, etc.)

       Returns:       AL         00h if only one letter is assigned to the
                                          block device
                                 Drive letter used most recently (1 = A,
                                          2 = B, etc.)
                      AX         Error code, if CF is set

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    Some block devices use more than one drive letter to refer to the same
    device.  For example, the floppy disk drive on a system with only one
    floppy disk drive can be referred to as either A: or B:.  This
    function tells both if more than one drive letter refers to a device
    and, if so, which drive letter was used most recently.

       Notes:         Function 440Fh can be used to set the most-recent
                      drive letter used for a device.