==========================================================================
code      operation
---------+----------------------------------------------------------------
  3       OPEN
  5       GET RECORD
  7       GET CHARACTERS
  8       PUT RECORD
 11       PUT CHARACTERS
 12       CLOSE
 13       STATUS REQUEST
 17       DRAW LINE
 18       FILL
 32       RENAME
 33       DELETE
 34       CREATE DIRECTORY (MyDOS)
 34       LOCK DISK (SpartaDOS 2.3/3.2)
 35       LOCK FILE
 36       UNLOCK FILE
 37       POINT
 38       NOTE
 39       GET FILE LENGTH (SpartaDOS)
 40       LOAD BINARY FILE
 41       SAVE BINARY FILE (Atari DOS, SpartaDOS 2.3/3.2)
 41       CHANGE DIRECTORY (MyDOS)
 42       CREATE DIRECTORY (SpartaDOS)
 43       DELETE DIRECTORY (SpartaDOS)
 44       CHANGE DIRECTORY (SpartaDOS)
 45       SET BOOT FILE (SpartaDOS)
 46       UNLOCK DISK (SpartaDOS 2.3/3.2)
 49       SET FILE ATTRIBUTES (SpartaDOS X)
253       FORMAT SINGLE DENSITY (DOS 2.5)
254       FORMAT DISK (default format)