Int 21 Fn 440F  - Dos 3.2+ - Ioctl - Set Logical Drive Map                 [D]

   AX = 440Fh
   BL = physical drive number (00h=default,01h=A:,etc))

Return: CF set on error
       AX = error code (01h,0Fh) (see #1366 at AH=59h/BX=0000h)
   CF clear if successful
       drive now responds to next logical drive number

Notes: maps logical drives to physical drives, similar to DOS's treatment of
     a single physical floppy drive as both A: and B:
   DR DOS 3.41-5.0 DRIVER.SYS does not support drive mapping and thus
     always returns an error on this function

See Also: AX=440Eh,INT 2F/AX=122Bh