39H MkDir: create a new directory      3cH create file
3aH RmDir: remove a directory          41H delete file

3bH ChDir: select default directory    0eH select current default disk
47H query current default directory    19H query current default disk
56H rename a directory

5700H      query file time/date        5701H change file time/date
4eH or 42H query file size             42H   change file size (pre-allocate)
4300H      query file attribute        4301H change file attribute
56H   change a file's name/move it

5cH lock/unlock file access            Network and File-Sharing Functions
68H commit (flush buffers to disk)
0dH reset disk (flush buffers)         IOCTL Functions (file/device info)

4eH 4fH search for files via ASCIIZ filename (get file info)
11H 12H search current directory via FCB (get DirEntryRec)

Directory and File Functions