Int 21 Fn 39  - DOS 2+ - "mkdir" - Create Subdirectory                     [D]

   AH = 39h
   DS:DX -> ASCIZ pathname

Return: CF clear if successful
       AX destroyed
   CF set on error
       AX = error code (03h,05h) (see AH=59h)

Notes: all directories in the given path except the last must exist
   fails if the parent directory is the root and is full
   DOS 2.x-3.3 allow the creation of a directory sufficiently deep that
     it is not possible to make that directory the current directory
     because the path would exceed 64 characters
   under the FlashTek X-32 DOS extender, the pointer is in DS:EDX

See Also: AH=3Ah,AH=3Bh,AH=6Dh,AH=E2h/SF=0Ah,INT 2F/AX=1103h