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CONFIG.SYS directives::CONFIG.SYS

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CONFIG.SYS directives

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#invoke:anchor|main}} : (DR DOS 5.0 and higher only) : Defines labels in CONFIG.SYS as jump targets for CHAIN, DRSWITCH, GOTO, GOSUB and SWITCH directives.
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#invoke:anchor|main}} ; (DOS 6.0 and DR DOS 6.0 and higher) : Similar to REM, but can be used also for in-line comments (following other CONFIG.SYS directives). See COMMENT. (Under MS-DOS/PC DOS the inline-comment is not ignored if put in double-quotes.)
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#invoke:anchor|main}} * (PTS-DOS only) : Used to lead in in-line comments in addition to the ; directive.
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#invoke:anchor|main}} ? (DR DOS 3.41 and higher, Embedded DOS and FreeDOS only) : Displays a Yes/No query and (since DR DOS 5.0) optional message to ask the user for confirmation to execute the following CONFIG.SYS directives. (FreeDOS does not support optional messages, but optional conditions in conjunction with boot menus defined with MENU and MENUDEFAULT.) (DOS 6.0 and higher supports a similar feature by adding a ? after the corresponding CONFIG.SYS directive, f.e. DEVICE? or DEVICE?= instead of ?DEVICE. This variant is also supported by DR DOS.)
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#invoke:anchor|main}} ! (FreeDOS only) : Unconditionally execute the following CONFIG.SYS directive.
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#invoke:anchor|main}} ABORT (PTS-DOS only) : Specifies if programs can be aborted on errors.
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#invoke:anchor|main}} ACCDATE (MS-DOS 7.0 and higher only, ignored under DR-DOS 7.02 and higher):<ref name="Paul_1997_OD-A3"/> Configures which drives should store file access date stamps in the reserved area of directory entries in FAT file systems.<ref name="Microsoft_2006_ACCDATE"/>
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#invoke:anchor|main}} AT (PTS-DOS only) : Conditional execution on AT-compatible machines only.
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#invoke:anchor|main}} AUTOCHECK (PTS-DOS only) : Boot manager.
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#invoke:anchor|main}} AUTOFAIL (OS/2 only) : Configures verbosity of error messages.
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#invoke:anchor|main}} AUX (DR-DOS 7.02 and higher only) : Changes internal default serial device driver (COM1: to COM4:) for AUX: device.<ref name="Paul_1997_OD-A3"/>
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#invoke:anchor|main}} AVAILDEV (DOS 2.0-2.1 and DR-DOS 7.02 and higher only<ref name="Paul_1997_OD-A3"/>) : Disables the availability of character devices outside phantom \DEV directory.
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#invoke:anchor|main}} BASEDEV (OS/2 only) : Loads base device driver into memory.
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#invoke:anchor|main}} BEEP (DR-DOS 7.02 and higher only) : Emits a short beep, even if audible notifications are disabled via SWITCHES=/Q.<ref name="Paul_1997_OD-A3"/>
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#invoke:anchor|main}} BOOTNEXT (DRMK only) : Specifies operating system to be booted.
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#invoke:anchor|main}} BREAK (DOS 2.0 and DR DOS 3.31 and higher; OS/2) : Sets or clears extended Ctrl+C checking.
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#invoke:anchor|main}} BUFFERS (DOS 2.0 and DR DOS 3.31 and higher; OS/2) : Specifies the number of disk buffers to allocate.
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#invoke:anchor|main}} BUFFERSHIGH (MS-DOS 7.0 and DR-DOS 7.02 and higher and FreeDOS only) : Same as BUFFERS, but explicitly loads buffers into HMA or UMB (like HIBUFFERS under DR DOS 6.0 and higher).
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#invoke:anchor|main}} CACHESIZE (Embedded DOS 6-XL only) : Maximum number of 512-byte cache blocks dynamically allocated from system pool.
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#invoke:anchor|main}} CACHETTL (Embedded DOS 6-XL only) : Maximum time in ms before unused cache blocks are returned to system pool.
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#invoke:anchor|main}} CACHEFLUSH (Embedded DOS 6-XL only) : Maximum time in ms before a dirty cache block gets flushed to disk.
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#invoke:anchor|main}} CALL (OS/2 4.0 and higher only) : Similar to INSTALL under DOS, loads programs in CONFIG.SYS. Similar to RUN under OS/2, but runs in foreground and halts CONFIG.SYS processing until return.
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#invoke:anchor|main}} CAPSLOCK (DR-DOS 7.02 and higher only) : Specifies whether the keyboard Caps Lock status is turned on or off.<ref name="Paul_1997_OD-A3"/>
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#invoke:anchor|main}} CDDNAME (PTS-DOS only) : Specifies the name of the CD-ROM hardware driver.
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#invoke:anchor|main}} CDDBUFFERS (PTS-DOS only) : Specifies the number of buffers for CD-ROM access.
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#invoke:anchor|main}} CHAIN (DR DOS 5.0 and higher and Embedded DOS only) : Continues CONFIG.SYS processing in new file and (since DR-DOS 7.02) at optional label.<ref name="Paul_1997_OD-A3"/>
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#invoke:anchor|main}} CLOCK (PTS-DOS only) : Specifies the type of clock used by the system.
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#invoke:anchor|main}} CLS (DR DOS 6.0 and higher only) : Clears screen.
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#invoke:anchor|main}} CODEPAGE (OS/2 only) : Specifies the OEM codepage(s).
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#invoke:anchor|main}} CMOSADDR (PTS-DOS only) : Specifies the address of the CMOS RAM.
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#invoke:anchor|main}} COLOR (PTS-DOS only) : Specifies colors for boot menus.
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#invoke:anchor|main}} COM1 (DR-DOS 7.02 and higher only): Defines count and logical order and configures I/O address and timeout for COM1: device.
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#invoke:anchor|main}} COM2 (DR-DOS 7.02 and higher only) : Defines count and logical order and configures I/O address and timeout for COM2: device.
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#invoke:anchor|main}} COM3 (DR-DOS 7.02 and higher only) : Defines count and logical order and configures I/O address and timeout for COM3: device.
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#invoke:anchor|main}} COM4 (DR-DOS 7.02 and higher only) : Defines count and logical order and configures I/O address and timeout for COM4: device.
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#invoke:anchor|main}} COMAREA (PTS-DOS only) : Specifies buffer for DMA.
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#invoke:anchor|main}} COMMENT (DOS 4.0 and higher and RxDOS, ignored under DR-DOS 7.02 and higher,<ref name="Paul_1997_OD-A3"/> under Embedded DOS and under PTS-DOS) : Redefines the lead-in character(s) for CONFIG.SYS inline-comments, or causes the following line to be ignored.
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#invoke:anchor|main}} COUNTRY (DOS 3.0 and DOS Plus 2.1 with FIDDLOAD and DR DOS 3.31 and higher; OS/2) : Enables and configures international support.
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#invoke:anchor|main}} CPOS (DR DOS 6.0 and higher only) : Sets display cursor to specified position for configuration menus.
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#invoke:anchor|main}} CPSW (MS-DOS 4.00-4.01 only, ignored under DR-DOS 7.02 and higher):<ref name="Paul_1997_OD-A3"/> For codepage switching support.
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#invoke:anchor|main}} CPU (PTS-DOS only) : Specifies RAM refresh speed.
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#invoke:anchor|main}} CPU88 (PTS-DOS only) : Conditional execution on 8088 CPUs only.
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#invoke:anchor|main}} CPU88+ (PTS-DOS only) : Conditional execution on 8088 and higher CPUs only.
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#invoke:anchor|main}} CPU86 (PTS-DOS only) : Conditional execution on 8086 CPUs only.
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#invoke:anchor|main}} CPU86+ (PTS-DOS only) : Conditional execution on 8086/8088 and higher CPUs only.
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#invoke:anchor|main}} CPU286 (PTS-DOS only) : Conditional execution on 286 CPUs only.
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#invoke:anchor|main}} CPU286+ (PTS-DOS only) : Conditional execution on 286 and higher CPUs only.
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#invoke:anchor|main}} CPU386 (DR-DOS 7.02 and higher<ref name="Paul_1997_OD-A3"/> and PTS-DOS only): Conditional execution on 386 and higher CPUs only, f.e. CPU386 DEVICE=C:\DOS\EMM386.EXE or CPU386 GOTO label386
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#invoke:anchor|main}} CPU386+ (PTS-DOS only) : Conditional execution on 386 and higher CPUs only.
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#invoke:anchor|main}} CPU486 (PTS-DOS only) : Conditional execution on 486 CPUs only.
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#invoke:anchor|main}} CPU486+ (PTS-DOS only) : Conditional execution on 486 and higher CPUs only.
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#invoke:anchor|main}} DDSCS (EDR-DOS 7.01.07 only) : Configures the relocation of the drive descriptor tables.
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#invoke:anchor|main}} DEBLOCK (DR DOS 6.0 (1993 update) and higher only) : Specifies the memory segment address up to which multi-sector disk data deblocking is allowed.
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#invoke:anchor|main}} DEBUG (DR DOS 3.31 - 6.0 and 7.02 and higher only) : Enables internal debugger support.
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#invoke:anchor|main}} DEFAULT (PTS-DOS only) : Boot manager.
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#invoke:anchor|main}} DEVICE (DOS 2.0 and DOS Plus 2.1 with FIDDLOAD and DR DOS 3.31 and higher; OS/2) : Loads a device driver into memory.
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#invoke:anchor|main}} DEVICEHIGH (DOS 5.0 and DR DOS 6.0 and higher; OS/2) : Loads a device driver into upper memory. (Same as HIDEVICE in DR DOS 5.0.)
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#invoke:anchor|main}} DEVINFO (OS/2 only) : Configures country and codepage information for KBD, SCR, LPT1, LPT2, LPT3 devices.
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#invoke:anchor|main}} DISKCACHE (OS/2 only, ignored under DR-DOS 7.02 and higher) : Configures cache memory sizes.
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#invoke:anchor|main}} DISKETTE (PTS-DOS only) : Specifies floppy disk compatibility mode.
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#invoke:anchor|main}} DISPLAY (PTS-DOS only) : Specifies display font.
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#invoke:anchor|main}} DOS (DOS 5.0 and DR DOS 6.0 and higher; OS/2) : Specifies whether to load DOS into the high memory area and/or use upper memory. (Similar to HIDOS=ON under DR DOS 5.0.)
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#invoke:anchor|main}} DOSDATA (PC DOS 7.0 and higher, FreeDOS, EDR-DOS 7.01.07 and DRMK only) : Specifies whether to load DOS tables (BUFFERS, FCBS, FILES, LASTDRIVE, STACKS) into upper memory.
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#invoke:anchor|main}} DOSDIR (PTS-DOS only) : Specifies alternative path to search for DOS files.
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#invoke:anchor|main}} DPBS (DRMK only)
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#invoke:anchor|main}} DPATH (OS/2 3.0 and higher only) : Specifies the search path for data files.
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#invoke:anchor|main}} DRIVATTR (PTS-DOS only) : Specifies physical parameters of disk drives.
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#invoke:anchor|main}} DRIVPARM (DOS 3.2 and higher) : Define parameters for unrecognized drives.
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#invoke:anchor|main}} DRSWITCH (DR DOS 7.02 and higher only) : See SWITCH.
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#invoke:anchor|main}} DUMPPROCESS (OS/2 3.0 and higher only) : Enables and specifies drive for PDUMP.nnn error logs.
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#invoke:anchor|main}} ECHO (DR DOS 5.0 and higher, and PTS-DOS and FreeDOS only) : Displays a message on screen.
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#invoke:anchor|main}} EECHO (FreeDOS only) : Displays a message including ANSI Escape sequences.
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#invoke:anchor|main}} ERREXE (PTS-DOS only) : Specifies if additional checks should be carried out when starting programs.
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#invoke:anchor|main}} ERROR (DR DOS 6.0 and higher only) : Specifies an error / return code to be assumed in the following.
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#invoke:anchor|main}} EXECA20OFF (PTS-DOS only) : Specifies the state of the A20 gate when starting a program.
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#invoke:anchor|main}} EXIT (DR DOS 6.0 and higher only) : Finishes CONFIG.SYS processing before the end of the file has been reached (except for SWITCHES and SHELL directive processing under some conditions).
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#invoke:anchor|main}} FASTOPEN (DR DOS 3.31 and higher and PTS-DOS only): Specified the size of the hash table for fast file open operations. Works considerably differently from the external MS-DOS/PC DOS FASTOPEN driver.
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#invoke:anchor|main}} FCBS (DOS 3.0 and DR DOS 3.31 and higher; OS/2) : Specifies the number of cached FCBs that can be opened at once. (Under DR-DOS, FCBS and FILES dynamically share the same internal buffer.)
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#invoke:anchor|main}} FCBSHIGH (MS-DOS 7.0 and DR-DOS 7.02 and higher only<ref name="Paul_1997_OD-A3"/>) : Same as FCBS, but explicitly loads FCBs into upper memory.
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#invoke:anchor|main}} FILENAME (PTS-DOS only) : Boot manager.
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#invoke:anchor|main}} FILES (DOS 2.0 and DR DOS 3.31 and higher; OS/2) : Specifies the number of files that can be opened at once.
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#invoke:anchor|main}} FILESHIGH (MS-DOS 7.0 and DR-DOS 7.02 and higher<ref name="Paul_1997_OD-A3"/> and FreeDOS only) : Same as FILES, but explicitly loads file handles into upper memory.
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#invoke:anchor|main}} FORCE (PTS-DOS only) : Include execution of specified CONFIG.SYS subsections. See IGNORE.
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#invoke:anchor|main}} GETKEY (DR DOS 6.0 and higher only) : Waits for key (or timeout) and sets error level to its ASCII code (or 1024 on timeout).
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#invoke:anchor|main}} GOTO (DR DOS 5.0 and higher only) : Continues CONFIG.SYS processing at specified label.
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#invoke:anchor|main}} GOSUB (DR DOS 6.0 and higher only) : Continues nested CONFIG.SYS processing at specified label, with RETURN returning to old location.
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#invoke:anchor|main}} HIBUFFERS (DR DOS 6.0 and higher only) : See BUFFERSHIGH or DOS=HIGH,UMB or DOSDATA.
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#invoke:anchor|main}} HIDEVICE (DR DOS 5.0 and higher only) : See DEVICEHIGH.
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#invoke:anchor|main}} HIDOS (DR DOS 5.0 and higher only) : See DOS=HIGH,UMB.
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#invoke:anchor|main}} HIFCBS (DR DOS 7.02 and higher,<ref name="Paul_1997_OD-A3"/>) EDR-DOS 7.01.07 and DRMK only) : See FCBSHIGH or DOSDATA.
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#invoke:anchor|main}} HIFILES (DR DOS 7.02 and higher,<ref name="Paul_1997_OD-A3"/>) EDR-DOS 7.01.07 and DRMK only) : See FILESHIGH or DOSDATA.
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#invoke:anchor|main}} HIINSTALL (DR DOS 5.0 and higher only) : See INSTALLHIGH.
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#invoke:anchor|main}} HIINSTALLLAST (EDR-DOS 7.01.07 and DRMK only) : Installs a TSR program into memory, like HIINSTALL, but installs after the DOS data segment relocation.
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#invoke:anchor|main}} HILASTDRIVE (DR-DOS 7.02 and higher, EDR-DOS 7.01.07 and DRMK only) : See LASTDRIVEHIGH or DOS=UMB or DOSDATA.
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#invoke:anchor|main}} HISHELL (DR-DOS 7.02 and higher only) : See SHELLHIGH.
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#invoke:anchor|main}} HISTACKS (DR-DOS 7.02 and higher, EDR-DOS 7.01.07 and DRMK only) : See STACKSHIGH or DOSDATA.
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#invoke:anchor|main}} HISTORY (DR DOS 3.41 and higher only) : Enables and configures console and command line history buffer and extended pattern search functionality.
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#invoke:anchor|main}} HMAREA (PTS-DOS only) : Specifies the address of the HMA segment.
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#invoke:anchor|main}} IDLEHALT (FreeDOS only) : Configures HLT energy saving.
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#invoke:anchor|main}} IDTCHK (PTS-DOS only) : Specifies if the system should check for boot sector viruses.
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#invoke:anchor|main}} IFS (MS-DOS 4.00-4.01 only, ignored under DR-DOS 7.02 and higher; OS/2) : Loads installable file systems.
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#invoke:anchor|main}} IGNORE (PTS-DOS only) : Exclude execution of specified CONFIG.SYS subsections. See FORCE.
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#invoke:anchor|main}} IOPL (OS/2 only) : Specifies programs (which would normally run at the CPU's IOPL ring 3) which should be allowed to run at ring 2 in order to directly access the hardware for I/O.
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#invoke:anchor|main}} INCLUDE (DOS 6.0 and higher, not DR-DOS, not FreeDOS) : Include directives from another menu block. (Can be emulated using GOSUB and RETURN under DR-DOS.)
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#invoke:anchor|main}} INSERT (DR-DOS 7.02 and higher only) : Specifies whether the keyboard Insert mode status is turned on or off.
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#invoke:anchor|main}} INSTALL (DOS 4.0 and DR DOS 3.41 and higher) : Installs a TSR program into memory.<ref name="Paul_1997_NWDOSTIP"/><ref name="4DOS_8.00_HELP"/>
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#invoke:anchor|main}} INSTALLHIGH (DOS 6.0 and DR DOS 6.0 and higher) : Installs a TSR program into upper memory. (Same as HIINSTALL in DR DOS 5.0.)
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#invoke:anchor|main}} INSTALLLAST (EDR-DOS 7.01.07 and DRMK only) : Installs a TSR program into memory, like INSTALL, but installs after the DOS data segment relocation.
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#invoke:anchor|main}} IRQPRIORITY (Embedded DOS 6-XL only) : Rotates PIC controller interrupt priorities so that specified number gets the highest priority
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#invoke:anchor|main}} KEYBOARD (PTS-DOS only) : Specifies the keyboard layout.
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#invoke:anchor|main}} KEYBUF (FreeDOS only) : Specifies the address of the relocated keyboard buffer.
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#invoke:anchor|main}} LASTDRIVE (DOS 3.0 and DOS Plus 2.1 with FIDDLOAD and DR DOS 3.31 and higher; OS/2) : Specifies the maximum of drives that can be accessed.
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#invoke:anchor|main}} LASTDRIVEHIGH (MS-DOS 7.0 and DR-DOS 7.02 and higher<ref name="Paul_1997_OD-A3"/>) and FreeDOS only) : Same as LASTDRIVE, but explicitly loads the Current Directory Structure (CDS) into upper memory.
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#invoke:anchor|main}} LIBPATH (OS/2 only) : Specifies a list of search paths for DLLs.
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#invoke:anchor|main}} LOADFIX (PTS-DOS only) : Specifies how old programs should be handled.
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#invoke:anchor|main}} LOCKS (PTS-DOS only) : Specifies number of file locks.
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#invoke:anchor|main}} LOGO (MS-DOS 7.0 and higher and PTS-DOS only, ignored under DR-DOS 7.02 and higher) : Configures boot logo support under MS-DOS. Allows to display startup message in conjunction with PTS-DOS boot manager.
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#invoke:anchor|main}} LPT1 (DR-DOS 7.02 and higher only) : Defines count and logical order and configures I/O address and timeout for LPT1: device.
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#invoke:anchor|main}} LPT2 (DR-DOS 7.02 and higher only) : Defines count and logical order and configures I/O address and timeout for LPT2: device.
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#invoke:anchor|main}} LPT3 (DR-DOS 7.02 and higher only) : Defines count and logical order and configures I/O address and timeout for LPT3: device.
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#invoke:anchor|main}} LPT4 (some versions of DR-DOS 7.02 and higher only<ref name="Paul_1997_OD-A3"/>)) : Enables, defines count and logical order and configures I/O address and timeout for LPT4: device.
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#invoke:anchor|main}} MAXWAIT (OS/2 only) : Specifies time before a waiting process gets a higher priority.
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#invoke:anchor|main}} MEMMAN (OS/2 only) : Configures memory allocation strategy
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#invoke:anchor|main}} MEMORY (PTS-DOS only) : Specifies the default DOS memory allocation strategy.
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#invoke:anchor|main}} MENU (FreeDOS only) : Defines menu options.
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#invoke:anchor|main}} MENUCOLOR (DOS 6.0 and higher, not DR DOS, not FreeDOS) : Specifies menu colors. (Can be emulated using ECHO under DR-DOS.)
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#invoke:anchor|main}} MENUDEFAULT (DOS 6.0 and higher and FreeDOS, not DR DOS) : Specifies the default menu block. (Can be emulated using TIMEOUT and SWITCH under DR-DOS.)
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#invoke:anchor|main}} MENUITEM (DOS 6.0 and higher, not DR DOS, not FreeDOS) : Specifies a menu block. (Can be emulated using ECHO and SWITCH under DR-DOS.)
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#invoke:anchor|main}} MULTITRACK (DOS 4.0 and DR-DOS 7.02 and higher;<ref name="Paul_1997_OD-A3"/>) ignored under PTS-DOS) : Specifies whether multitrack disk operations are used or not.
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#invoke:anchor|main}} NOCHAR (DR-DOS 7.02 and higher only) : Specifies the default No (N) character in Yes/No/Resume questions.<ref name="Paul_1997_OD-A3"/>)
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#invoke:anchor|main}} NUMLOCK (DOS 6.0 and Novell DOS 7 and higher) : Specifies whether the keyboard Num Lock status is turned on or off.
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#invoke:anchor|main}} ONERROR (DR DOS 6.0 and higher only) : Conditional execution depending on last return code/error status only, f.e. ONERROR > 0 GOTO failload or ONERROR > 10 ONERROR <> 17 ONERROR <= 30 ECHO Error 11-16 or 18-30 occurred.<ref name="Paul_1997_NWDOSTIP"/>
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#invoke:anchor|main}} PAUSE (PTS-DOS only) : Similar to ECHO and GETKEY under DR-DOS, displays a text and waits for a key press.
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#invoke:anchor|main}} PAUSEONERROR (OS/2 only) : Specifies if user must acknowledge errors in CONFIG.SYS.
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#invoke:anchor|main}} PRINTMONBUFSIZE (OS/2 only) : Configures buffer size for LPT1, LPT2, LPT3.
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#invoke:anchor|main}} PC (PTS-DOS only) : Conditional execution on PC-compatible machines only.
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#invoke:anchor|main}} PRIORITY (OS/2 only) : Configures priority scheduler.
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#invoke:anchor|main}} PRIORITY_DISK_IO (OS/2 only) : Configures priority of programs using disk I/O.
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#invoke:anchor|main}} PRN (DR-DOS 7.02 and higher only): Changes internal default printer device driver (LPT1 to LPT3, or even LPT4) for PRN device.<ref name="Paul_1997_OD-A3"/>
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#invoke:anchor|main}} PROTECTONLY (OS/2 only) : Specifies if DOS programs can be run or not.
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#invoke:anchor|main}} PROTSHELL (OS/2 only) : Loads user interface.
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#invoke:anchor|main}} PS1 (PTS-DOS only) : Conditional execution on PS/1-compatible machines only.
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#invoke:anchor|main}} PS2 (PTS-DOS only) : Conditional execution on PS/2-compatible machines only.
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#invoke:anchor|main}} QUIET (PTS-DOS and DRMK only) : Mutes display output send to STDOUT.
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#invoke:anchor|main}} REIPL (OS/2 3.0 and higher only) : Specifies if system should reboot automatically on errors.
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#invoke:anchor|main}} REM (DOS 4.0 and DR DOS 3.31 and higher; ignored under PTS-DOS) : Allows comments in CONFIG.SYS.
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#invoke:anchor|main}} RESERVEDRIVELETTER (OS/2 3 FixPack 24 and higher only) : Specifies a drive letter not to be used up for local block device drivers.
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#invoke:anchor|main}} RESUMECHAR (DR-DOS 7.02 and higher only): Specifies the default Resume (R) character in Yes/No/Resume queries.<ref name="Paul_1997_OD-A3"/>)
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#invoke:anchor|main}} RETURN (DR DOS 6.0 and higher only) : Returns nested CONFIG.SYS processing at previous location of GOSUB or SWITCH directive. An optional return code can be given, otherwise 0 is assumed.
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#invoke:anchor|main}} RMSIZE (OS/2 only, ignored under DR-DOS 7.02 and higher) : Defines the real mode memory size.
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#invoke:anchor|main}} RUN (OS/2 only) : Similar to CALL, loads programs in CONFIG.SYS. Similar to INSTALL under DOS and CALL under OS/2, but loads programs in background concurrenty.
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#invoke:anchor|main}} SAVENAME (PTS-DOS only) : Specifies, if the first character of deleted files should be stored in the reserved area of directory entries in the FAT file system.
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#invoke:anchor|main}} SCREEN (FreeDOS and PTS-DOS only) : Similar to VIDEOMODE under PTS-DOS, specifies the video mode to be used under FreeDOS. Under PTS-DOS, SCREEN does not specify the video mode but screen access methods.
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#invoke:anchor|main}} SCROLLOCK (DR-DOS 7.02 and higher only) : Specifies whether the keyboard Scroll Lock status is turned on or off.<ref name="Paul_1997_OD-A3"/>)
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#invoke:anchor|main}} SET (DOS 6.0 and DR DOS 6.0 and higher; OS/2) : Sets environment variables.
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#invoke:anchor|main}} SHELL (DOS 2.0 and DR DOS 3.31 and higher; OS/2) : Loads the command interpreter shell.
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#invoke:anchor|main}} SHELLHIGH (DR-DOS 7.02 and higher and PTS-DOS and FreeDOS only) : Same as SHELL, but supports an additional SIZE parameter to define the size of the pre-allocation for COMMAND.COM to relocate its resident portion into the HMA (with /MH). Can be useful to avoid HMA fragmentation in conjunction with third-party shells which cannot load into the HMA. SHELLHIGH under PTS-DOS tries to load the shell into UMBs instead.)<ref name="Paul_1997_OD-A3"/><ref name="4DOS_8.00_HELP"/>
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#invoke:anchor|main}} SHIFTSTATE (PTS-DOS only) : Specifies the state of the keyboard modifiers like Shift Lock, Num Lock, Scroll Lock or Insert mode.
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#invoke:anchor|main}} SHUTDOWN (PTS-DOS only) : Specifies if files should be closed on Ctrl+Alt+Del.
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#invoke:anchor|main}} SOFTREBOOT (PTS-DOS only) : Specifies if POST should be skipped on reboots.
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#invoke:anchor|main}} STACK (ignored under DR DOS 3.31-5.0 and 7.02 and higher only) : Compatibility dummy - DR DOS 3.31 - 6.0 were mostly reentrant and had a different stacks layout.
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#invoke:anchor|main}} STACKS (DOS 3.2 and Novell DOS 7 and higher, ignored under DR DOS 6.0 and PTS-DOS) : Specifies the number of stacks for hardware interrupts.
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#invoke:anchor|main}} STACKSIZE (Embedded DOS 6-XL only) : Default size size allocated for new threads.
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#invoke:anchor|main}} STACKSHIGH (MS-DOS 7.0 and DR-DOS 7.02 and higher<ref name="Paul_1997_OD-A3"/>) and FreeDOS only) : Same as STACKS, but explicitly loads buffers into upper memory.
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#invoke:anchor|main}} STORAGE (PTS-DOS only) : Boot manager.
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#invoke:anchor|main}} STRING (MS-DOS 3.0 only, ignored under DR-DOS 7.02 and higher) : Internal use.
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#invoke:anchor|main}} STUBA20 (PTS-DOS only) : Specifies how XMS A20 gate control should work.
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#invoke:anchor|main}} SUBMENU (DOS 6.0 and higher, not DR DOS, not FreeDOS) : Specifies a submenu block. (Can be emulated using CLS, ECHO and SWITCH under DR-DOS.)
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#invoke:anchor|main}} SUPPRESSPOPUPS (OS/2 3.0 and higher only) : Specifies a drive where to log error information instead of displaying a textmode popup screen.
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#invoke:anchor|main}} SWAPPATH (OS/2 only) : Specifies swap file path.
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#invoke:anchor|main}} SWITCH (DR DOS 6.0 and higher only) : Conditionally continues nested CONFIG.SYS processing at one of the specified labels depending on keys pressed, with RETURN returning to old location.
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#invoke:anchor|main}} SWITCHAR (DOS 2.0-2.1, DOS Plus 2.1 with FIDDLOAD, DR-DOS 7.02 and higher,<ref name="Paul_1997_OD-A3"/>) PTS-DOS, FreeDOS and RxDOS only): Defines the default SwitChar used by the system (either '/' or '-').<ref name="4DOS_8.00_HELP"/>
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#invoke:anchor|main}} SWITCHES (DOS 4.0 and Novell DOS 7 and higher; ignored under PTS-DOS) : Specifies special options.
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#invoke:anchor|main}} SXFAKEHWFPU (OS/2 Warp 4 FixPak 1 (and higher) only) : Specifies if a fix for a FPU rounding bug should be activated or not.
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#invoke:anchor|main}} SYSBOOT (PTS-DOS only) : Specifies file name of alternative DOS operating systems to boot.
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#invoke:anchor|main}} SYSGEN (PTS-DOS only) : Configures the location of the various DOS parts in memory.
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#invoke:anchor|main}} SYSLOAD (PTS-DOS only) : Load system from alternative disk area.
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#invoke:anchor|main}} SYSTEMPOOL (Embedded DOS 6-XL only) : Size of system memory pool from which the system dynamically allocates for various purposes
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#invoke:anchor|main}} SYSTOUMB (PTS-DOS only) : Specifies if DOS data and code should be loaded into UMBs.
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#invoke:anchor|main}} THREADS (OS/2 only) : Specifies number of concurrent threads.
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#invoke:anchor|main}} TIMEOUT (DR DOS 6.0 and higher and PTS-DOS only) : Specifies the timeouts in CONFIG.SYS single-stepping and with SWITCH, GETKEY and ?, and the default answers for Yes/No queries and SWITCH selections. PTS-DOS only supports the timeout value.
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#invoke:anchor|main}} TIMESLICE (OS/2 only) : Configures minimum and maximum time slices for scheduler.
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#invoke:anchor|main}} TMPEXT (PTS-DOS only) : Specifies the file extension for temporary files.
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#invoke:anchor|main}} TRACE (DR-DOS 7.02 and higher and PTS-DOS only; OS/2) : Globally or locally enables or disables CONFIG.SYS (and AUTOEXEC.BAT) single-stepping execution. The functionality under OS/2 differs significantly from that under DOS.
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#invoke:anchor|main}} TRACEBUF (OS/2 only) : Specifies size of TRACE log buffer.
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#invoke:anchor|main}} TRAPDUMP (OS/2 3.0 and higher only) : Logs detailed error information.
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#invoke:anchor|main}} UMB (Embedded DOS only) : Configures DOS management to use a specific segment as UMB memory.
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#invoke:anchor|main}} UMBSRV (PTS-DOS only) : Configures the UMB server used.
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#invoke:anchor|main}} USERAM (PTS-DOS only) : Specifies the address ranges used as UMB RAM.
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#invoke:anchor|main}} VERIFY (DR-DOS 7.02 and higher and Embedded DOS only) : Enables or disables disk write verification.
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#invoke:anchor|main}} VERSION (FreeDOS, Embedded DOS, and EDR-DOS 7.01.07 only) : Specifies the DOS version (and optionally the true DOS version) to be reported to programs.
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#invoke:anchor|main}} VGASCREEN (PTS-DOS only) : Configures VGA display status.
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#invoke:anchor|main}} VIDEOMODE (PTS-DOS only) : Similar to SCREEN under FreeDOS, specifies current video mode.
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#invoke:anchor|main}} VIRTDMA (PTS-DOS only) : Specifies if virtual DMA can be used.
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#invoke:anchor|main}} VME (OS/2 only) : Specifies if the processor's Virtual Mode Extensions (VME) should be deactivated or not.
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#invoke:anchor|main}} VXD (PTS-DOS only) : Configures VxD driver for Windows.
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#invoke:anchor|main}} WINDOWS (PTS-DOS only) : Configures system support for Windows.
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#invoke:anchor|main}} XBDA (EDR-DOS 7.01.07 and DRMK only) : Configures the relocation of the Extended BIOS data area (XBDA)
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#invoke:anchor|main}} XT (PTS-DOS only) : Conditional execution on XT-compatible machines only.
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#invoke:anchor|main}} YEAR2000 (DR-DOS 7.02 and higher only) : Configures the built-in Year 2000 support.
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#invoke:anchor|main}} YESCHAR (PalmDOS 1.0, DR DOS 6.0 updates and Novell DOS 7 and higher only) : Specifies the default Yes (Y) character in Yes/No/Resume queries.
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#invoke:anchor|main}} ZOMBIEDRV (PTS-DOS only) : Configures deletion tracking.

CONFIG.SYS sections
Intro   Usage    CONFIG.SYS directives    Examples    Issues    Dual booting DOS and Windows 9x    OS/2 / NT    See also    References    External links   

CONFIG.SYS directives
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