HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

                 INT 21,6C - Extended Open/Create  (DOS 4.x+)

       AH = 6C
       AL = 00
       BX = open mode (see below)
       CX = file attribute (see FILE ATTRIBUTES, bits 15-8 are zero)
       DX = function control indicator (see below)
       DS:SI = ASCIIZ filespec


       returns:
       AX = handle if CF clear
          = error code if CF set  (see DOS ERROR CODES)
       CX = 01  file opened
          = 02  file created and opened
          = 03  file truncated and opened (replaced)
       CF = 0 if successful
          = 1 if error


       Open Mode in BX:

       │F│E│D│C│B│A│9│8│7│6│5│4│3│2│1│0│  BX  (Open Mode)
        │ │ │ │ │ │ │ │ │ │ │ │ │ └─┴─┴──── read/write access mode
        │ │ │ │ │ │ │ │ │ │ │ │ └──────── reserve (must be 0)
        │ │ │ │ │ │ │ │ │ └─┴─┴──────── sharing mode
        │ │ │ │ │ │ │ │ └──────────── 1 = private, 0 = inheritable
        │ │ │ └─┴─┴─┴─┴──────────── reserved
        │ │ └──────────────────── 0 = call INT 24, 1 = ignore INT 24
        │ └──────────────────── 0 = normal write, 1 = flush each write
        └──────────────────── reserved

       Read/Write Access bits:     Sharing Mode bits:
       210                           654
       000  read access              000  compatibility mode
       001  write access             001  read/write access
       010  read/write access        010  write access denied
                                     011  read access denied
                                     100  full access

       Function Control Indicator in DX:

       │F│E│D│C│B│A│9│8│7│6│5│4│3│2│1│0│  DX  (Function Control)
        │ │ │ │ │ │ │ │ │ │ │ │ └─┴─┴─┴──── file existence behavior
        │ │ │ │ │ │ │ │ └─┴─┴─┴─────────── creation behavior
        └─┴─┴─┴─┴─┴─┴─┴────────────────── reserved

       File Existence Behavior bits:
       3210
       0000  if file exist, generate error, take no action
       0001  if file exists, open file
       0010  if file exists, truncate and open


       Creation Behavior bits:
       7654
       0000  if file does not exist, generate error, take no action
       0001  if file does not exist, create

Esc or Alt-X to exit int 21,6c Home/PgUp/PgDn/End ←↑↓→