Int 21H, AH=39H

2 and higher

“MKDIR” - CREATE SUBDIRECTORY

      AH = 39h
      DS:DX -> ASCIZ pathname

CF clear if successful

          AX destroyed
      CF set on error
          AX = error code (03h,05h) (see #01680 at AH=59h/BX=0000h)

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
        

AH=3Ah,AH=3Bh,AH=6Dh,AX=7139h,AH=E2h/SF=0Ah,AX=43FFh/BP=5053h INT 2F/AX=1103h,INT 60/DI=0511h

Text based on Ralf Brown Interrupt List Release 61