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  Interrupt:   21h     Function:   0Fh
 
  Title:       Open File
 
  See also:    Open File (handle)
 
  Description:
 
     Opens a file and makes it available for subsequent read/write
     operations.
 
     Input                       Output
 
     AH = 0Fh                    If function successful (file found)
     DS:DX = segment:offset        AL = 00
             of file control     And FCB filled in by MS-DOS as
             block               follows:
                                 ■ Drive field (offset 00h0) = 1 for
                                   drive A, 2 for drive B,...
                                 ■ Current block field (offset 0Ch) = 00h
                                 ■ Record size field (offset 0Eh) = 0080h
                                 ■ Size field (offset 10h) = File size
                                   from directory
                                 ■ Date field (offset 14h) = Date stamp
                                   from directory
                                 ■ Time field (offset 16h) = Time stamp
                                   from directory
 
                                 If function unsuccessful
                                 (file not found)
                                   AL = 0FFh
                                    -♦-