Editing CONFIG.SYS (section)

== Directives ==

=== :;*?! ===
<!-- TBD: Check if the following are actually OS/2 CONFIG.SYS directives or only reserved environment variable names to be used in conjunction with SET: AUTOREFRESHFOLDERS, MENUSTYLE, OBJECTSNOOZETIME, SHAPIEXCEPTIONHANDLER, SHELLEXCEPTIONHANDLER. -->
;{{anchor|:}} {{mono|1=<nowiki>:</nowiki>}} {{nobold|(DR&nbsp;DOS 5.0 and higher only)}} : Defines labels in CONFIG.SYS as jump targets for {{mono|1=CHAIN}}, {{mono|1=DRSWITCH}}, {{mono|1=GOTO}}, {{mono|1=GOSUB}} and {{mono|1=SWITCH}} directives.
;{{anchor|;}} {{mono|1=;}} {{nobold|(DOS 6.0 and DR&nbsp;DOS 6.0 and higher)}} : Similar to {{mono|1=REM}}, but can be used also for in-line comments (following other CONFIG.SYS directives). See {{mono|1=COMMENT}}. (Under MS-DOS/PC&nbsp;DOS the inline-comment is not ignored if put in double-quotes.)
;{{anchor|*}} {{mono|1=*}} {{nobold|(PTS-DOS only)}} : Used to lead in in-line comments in addition to the ; directive.
;{{anchor|?}} {{mono|1=?}} {{nobold|(DR&nbsp;DOS 3.41<!-- or earlier? but not in 3.31 --> and higher, Embedded DOS<ref group="nb" name="embed">at least General Software Embedded DOS-ROM 4.1 and Embedded DOS 6-XL</ref> and FreeDOS only)}} : Displays a Yes/No query and (since DR&nbsp;DOS 5.0) optional message to ask the user for confirmation to execute the following CONFIG.SYS directives.<ref name="Paul_2000_CONFIG"/> (FreeDOS does not support optional messages, but optional conditions in conjunction with boot menus defined with {{mono|1=MENU}} and {{mono|1=MENUDEFAULT}}.) (DOS 6.0 and higher supports a similar feature by adding a {{mono|1=?}} after the corresponding CONFIG.SYS directive, f.e. {{mono|1=DEVICE?}} or {{mono|1=DEVICE?=}} instead of {{mono|1=?DEVICE}}. This variant is also supported by DR&nbsp;DOS.)
;{{anchor|!}} {{mono|1=!}} {{nobold|(FreeDOS only)}} : Unconditionally execute the following CONFIG.SYS directive.
=== A{{nbnd}}C ===
;{{anchor|ABORT}} {{mono|1=ABORT}} {{nobold|(PTS-DOS only)}} : Specifies if programs can be aborted on errors.
;{{anchor|ACCDATE}} {{mono|1=ACCDATE}} {{nobold|(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 [[FAT ACCDATE|reserved area]] of directory entries in [[File Allocation Table|FAT]] file systems.<ref name="Microsoft_1995_CONFIG"/><ref name="Microsoft_1998_CONFIG"/>
;{{anchor|AT}} {{mono|1=AT}} {{nobold|(PTS-DOS only)}} : Conditional execution on AT-compatible machines only.
;{{anchor|AUTOCHECK}} {{mono|1=AUTOCHECK}} {{nobold|(PTS-DOS only)}} : Boot manager.
;{{anchor|AUTOFAIL}} {{mono|1=AUTOFAIL}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Configures verbosity of error messages.
;{{anchor|AUX}} {{mono|1=AUX}} {{nobold|(DR-DOS 7.02 and higher only)}} : Changes internal default serial device driver ({{mono|1=COM1:}} to {{mono|1=COM4:}}) for {{mono|1=AUX:}} device.<ref name="Paul_1997_OD-A3"/>
;{{anchor|AVAILDEV}} {{mono|1=AVAILDEV}} {{nobold|(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.
;{{anchor|BASEDEV}} {{mono|1=BASEDEV}} {{nobold|(OS/2<ref group="nb" name="since2">at least since 2.0</ref> only)}} : Loads base device driver into memory.
;{{anchor|BEEP}} {{mono|1=BEEP}} {{nobold|(DR-DOS 7.02 and higher only)}} : Emits a short beep, even if audible notifications are disabled via {{mono|1=SWITCHES=/Q}}.<ref name="Paul_1997_OD-A3"/>
;{{anchor|BOOTNEXT}} {{mono|1=BOOTNEXT}} {{nobold|(DRMK only)}} : Specifies operating system to be booted.
;{{anchor|BREAK}} {{mono|1=BREAK}} {{nobold|(DOS 2.0 and DR&nbsp;DOS 3.31 and higher; OS/2<ref group="nb" name="since2"/><ref group="nb" name="pts">PTS-DOS also</ref>)}} : Sets or clears extended {{keypress|Ctrl|C}} checking.
;{{anchor|BUFFERS}} {{mono|1=BUFFERS}} {{nobold|(DOS 2.0 and DR&nbsp;DOS 3.31 and higher; OS/2<ref group="nb" name="since2"/><ref group="nb" name="pts"/>)}} : Specifies the number of disk buffers to allocate.
;{{anchor|BUFFERSHIGH}} {{mono|1=BUFFERSHIGH}} {{nobold|(MS-DOS 7.0<ref name="Microsoft_1995_CONFIG"/> and DR-DOS 7.02 and higher<ref name="Paul_1997_OD-A3"/> and FreeDOS only)}} : Same as {{mono|1=BUFFERS}}, but explicitly loads buffers into HMA or UMB (like {{mono|1=HIBUFFERS}} under DR DOS 6.0 and higher).
;{{anchor|CACHESIZE}} {{mono|1=CACHESIZE}} {{nobold|(Embedded DOS 6-XL only)}} : Maximum number of 512-byte cache blocks dynamically allocated from system pool.
;{{anchor|CACHETTL}} {{mono|1=CACHETTL}} {{nobold|(Embedded DOS 6-XL only)}} : Maximum time in ms before unused cache blocks are returned to system pool.
;{{anchor|CACHEFLUSH}} {{mono|1=CACHEFLUSH}} {{nobold|(Embedded DOS 6-XL only)}} : Maximum time in ms before a dirty cache block gets flushed to disk.
;{{anchor|CALL}} {{mono|1=CALL}} {{nobold|(OS/2 4.0<!-- or 3.0? --> and higher only)}} : Similar to {{mono|1=INSTALL}} under DOS, loads programs in CONFIG.SYS. Similar to {{mono|1=RUN}} under OS/2, but runs in foreground and halts CONFIG.SYS processing until return.
;{{anchor|CAPSLOCK}} {{mono|1=CAPSLOCK}} {{nobold|(DR-DOS 7.02 and higher only)}} : Specifies whether the keyboard {{keypress|[[Caps Lock]]}} status is turned on or off.<ref name="Paul_1997_OD-A3"/>
;{{anchor|CDDNAME}} {{mono|1=CDDNAME}} {{nobold|(PTS-DOS only)}} : Specifies the name of the CD-ROM hardware driver.
;{{anchor|CDDBUFFERS}} {{mono|1=CDDBUFFERS}} {{nobold|(PTS-DOS only)}} : Specifies the number of buffers for CD-ROM access.
;{{anchor|CHAIN}} {{mono|1=CHAIN}} {{nobold|(DR&nbsp;DOS 5.0 and higher and Embedded DOS<ref group="nb" name="embed"/> only)}} : Continues CONFIG.SYS processing in new file and (since DR-DOS 7.02) at optional label.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2004_CHAIN"/>
;{{anchor|CLOCK}} {{mono|1=CLOCK}} {{nobold|(PTS-DOS only)}} : Specifies the type of clock used by the system.
;{{anchor|CLS}} {{mono|1=CLS}} {{nobold|(DR&nbsp;DOS 6.0 and higher only)}} : Clears screen.
;{{anchor|CODEPAGE}} {{mono|1=CODEPAGE}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Specifies the OEM codepage(s).
;{{anchor|CMOSADDR}} {{mono|1=CMOSADDR}} {{nobold|(PTS-DOS only)}} : Specifies the address of the CMOS RAM.
;{{anchor|COLOR}} {{mono|1=COLOR}} {{nobold|(PTS-DOS only)}} : Specifies colors for boot menus.
;{{anchor|COM1}} {{mono|1=COM1}} {{nobold|(DR-DOS 7.02 and higher only)}} : Defines count and logical order and configures I/O address and timeout for [[COM1]]: device.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2002_CTMOUSE"/>
;{{anchor|COM2}} {{mono|1=COM2}} {{nobold|(DR-DOS 7.02 and higher only)}} : Defines count and logical order and configures I/O address and timeout for [[COM2]]: device.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2002_CTMOUSE"/>
;{{anchor|COM3}} {{mono|1=COM3}} {{nobold|(DR-DOS 7.02 and higher only)}} : Defines count and logical order and configures I/O address and timeout for [[COM3]]: device.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2002_CTMOUSE"/>
;{{anchor|COM4}} {{mono|1=COM4}} {{nobold|(DR-DOS 7.02 and higher only)}} : Defines count and logical order and configures I/O address and timeout for [[COM4]]: device.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2002_CTMOUSE"/>
;{{anchor|COMAREA}} {{mono|1=COMAREA}} {{nobold|(PTS-DOS only)}} : Specifies buffer for DMA.
;{{anchor|COMMENT|COMMENTS}} {{mono|1=COMMENT}} {{nobold|(DOS 4.0 and higher and RxDOS, ignored under DR-DOS 7.02 and higher,<ref name="Paul_1997_OD-A3"/> under Embedded DOS<ref group="nb" name="embed"/> and under PTS-DOS)}} : Redefines the lead-in character(s) for CONFIG.SYS inline-comments, or causes the following line to be ignored.
;{{anchor|COUNTRY}} {{mono|1=COUNTRY}} {{nobold|(DOS 3.0 and DOS&nbsp;Plus 2.1 with [[FIDDLOAD]] and DR&nbsp;DOS 3.31 and higher; OS/2<ref group="nb" name="since2"/><ref group="nb" name="pts"/>)}} : Enables and configures international support.
;{{anchor|CPOS}} {{mono|1=CPOS}} {{nobold|(DR&nbsp;DOS 6.0 and higher only)}} : Sets display cursor to specified position for configuration menus.
;{{anchor|CPSW}} {{mono|1=CPSW}} {{nobold|(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.
;{{anchor|CPU}} {{mono|1=CPU}} {{nobold|(PTS-DOS only)}} : Specifies RAM refresh speed.
;{{anchor|CPU88}} {{mono|CPU88}} {{nobold|(PTS-DOS only)}} : Conditional execution on 8088 CPUs only.
;{{anchor|CPU88+}} {{mono|CPU88+}} {{nobold|(PTS-DOS only)}} : Conditional execution on 8088 and higher CPUs only.
;{{anchor|CPU86}} {{mono|CPU86}} {{nobold|(PTS-DOS only)}} : Conditional execution on 8086 CPUs only.
;{{anchor|CPU86+}} {{mono|CPU86+}} {{nobold|(PTS-DOS only)}} : Conditional execution on 8086/8088 and higher CPUs only.
;{{anchor|CPU286}} {{mono|CPU286}} {{nobold|(PTS-DOS only)}} : Conditional execution on 286 CPUs only.
;{{anchor|CPU286+}} {{mono|CPU286+}} {{nobold|(PTS-DOS only)}} : Conditional execution on 286 and higher CPUs only.
;{{anchor|CPU386}} {{mono|CPU386}} {{nobold|(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. {{code|1=CPU386 DEVICE=C:\DOS\EMM386.EXE}} or {{code|2=bat|CPU386 GOTO label386}}
;{{anchor|CPU386+}} {{mono|CPU386+}} {{nobold|(PTS-DOS only)}} : Conditional execution on 386 and higher CPUs only.
;{{anchor|CPU486}} {{mono|CPU486}} {{nobold|(PTS-DOS only)}} : Conditional execution on 486 CPUs only.
;{{anchor|CPU486+}} {{mono|CPU486+}} {{nobold|(PTS-DOS only)}} : Conditional execution on 486 and higher CPUs only.
=== D{{nbnd}}F ===
;{{anchor|DDSCS}} {{mono|1=DDSCS}} {{nobold|(EDR-DOS 7.01.07 only)}} : Configures the relocation of the drive descriptor tables.
;{{anchor|DEBLOCK}} {{mono|1=DEBLOCK}} {{nobold|(DR{{nbh}}DOS 6.0 (1993 update) and higher only)}} : Specifies the memory segment address up to which multi-sector disk data [[deblocking (data storage)|deblocking]] is allowed.
;{{anchor|DEBUG}} {{mono|1=DEBUG}} {{nobold|(DR{{nbh}}DOS 3.31 - 6.0 and 7.02 and higher only<ref name="Paul_1997_OD-A3"/>)}} : Enables internal debugger support.
;{{anchor|DEFAULT}} {{mono|1=DEFAULT}} {{nobold|(PTS-DOS only)}} : Boot manager.
;{{anchor|DEVICE}} {{mono|1=DEVICE}} {{nobold|(DOS 2.0 and DOS Plus 2.1 with FIDDLOAD and DR{{nbh}}DOS 3.31 and higher; OS/2<ref group="nb" name="since2"/><ref group="nb" name="pts"/>)}} : Loads a device driver into memory.
;{{anchor|DEVICEHIGH}} {{mono|1=DEVICEHIGH}} {{nobold|(DOS 5.0 and DR{{nbh}}DOS 6.0 and higher; OS/2<ref group="nb" name="since2"/><ref group="nb" name="pts"/>)}} : Loads a device driver into upper memory. (Same as {{mono|1=HIDEVICE}} in DR{{nbh}}DOS 5.0.)
;{{anchor|DEVINFO}} {{mono|1=DEVINFO}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Configures country and codepage information for KBD, SCR, LPT1, LPT2, LPT3 devices.
;{{anchor|DISKCACHE}} {{mono|1=DISKCACHE}} {{nobold|(OS/2<ref group="nb" name="since2"/> only, ignored under DR-DOS 7.02 and higher)}} : Configures cache memory sizes.
;{{anchor|DISKETTE}} {{mono|1=DISKETTE}} {{nobold|(PTS-DOS only)}} : Specifies floppy disk compatibility mode.
;{{anchor|DISPLAY}} {{mono|1=DISPLAY}} {{nobold|(PTS-DOS only)}} : Specifies display font.
;{{anchor|DOS}} {{mono|1=DOS}}<ref name="Schneider_1994"/> {{nobold|(DOS 5.0 and DR{{nbh}}DOS 6.0 and higher; OS/2<ref group="nb" name="since2"/><ref group="nb" name="pts"/>)}} : Specifies whether to load DOS into the high memory area and/or use upper memory. (Similar to {{mono|1=HIDOS=ON}} under DR{{nbh}}DOS 5.0.)
;{{anchor|DOSDATA}} {{mono|1=DOSDATA}} {{nobold|(PC&nbsp;DOS 7.0 and higher, FreeDOS, EDR-DOS 7.01.07 and DRMK only)}} : Specifies whether to load DOS tables ({{mono|1=BUFFERS}}, {{mono|1=FCBS}}, {{mono|1=FILES}}, {{mono|1=LASTDRIVE}}, {{mono|1=STACKS}}) into upper memory.
;{{anchor|DOSDIR}} {{mono|1=DOSDIR}} {{nobold|(PTS-DOS only)}} : Specifies alternative path to search for DOS files.
;{{anchor|DPBS}} {{mono|1=DPBS}} {{nobold|(DRMK only)}}<!-- : . -->
;{{anchor|DPATH}} {{mono|1=DPATH}} {{nobold|(OS/2 3.0 and higher only)}} : Specifies the search path for data files.
;{{anchor|DRIVATTR}} {{mono|1=DRIVATTR}} {{nobold|(PTS-DOS only)}} : Specifies physical parameters of disk drives.
;{{anchor|DRIVPARM}} {{mono|1=DRIVPARM}} {{nobold|(DOS 3.2<ref group="nb">apparently not functional in all PC DOS 3.x version</ref> and higher<ref group="nb" name="pts"/>)}} : Define parameters for unrecognized drives.
;{{anchor|DRSWITCH}} {{mono|1=DRSWITCH}} {{nobold|(DR{{nbh}}DOS 7.02 and higher only)}} : See {{mono|1=SWITCH}}.<ref name="Paul_2000_CONFIG"/>
;{{anchor|DUMPPROCESS}} {{mono|1=DUMPPROCESS}} {{nobold|(OS/2 3.0 and higher only)}} : Enables and specifies drive for <code>PDUMP.nnn</code> error logs.
;{{anchor|ECHO}} {{mono|1=ECHO}} {{nobold|(DR{{nbh}}DOS 5.0 and higher, and PTS-DOS and FreeDOS only)}} : Displays a message on screen.
;{{anchor|EECHO}} {{mono|1=EECHO}} {{nobold|(FreeDOS only)}} : Displays a message including ANSI Escape sequences.
;{{anchor|ERREXE}} {{mono|1=ERREXE}} {{nobold|(PTS-DOS only)}} : Specifies if additional checks should be carried out when starting programs.
;{{anchor|ERROR}} {{mono|1=ERROR}} {{nobold|(DR{{nbh}}DOS 6.0 and higher only)}} : Specifies an error / return code to be assumed in the following.
;{{anchor|EXECA20OFF}} {{mono|1=EXECA20OFF}} {{nobold|(PTS-DOS only)}} : Specifies the state of the [[A20 gate]] when starting a program.
;{{anchor|EXIT}} {{mono|1=EXIT}} {{nobold|(DR{{nbh}}DOS 6.0 and higher only)}} : Finishes CONFIG.SYS processing before the end of the file has been reached (except for {{mono|1=SWITCHES}} and {{mono|1=SHELL}} directive processing under some conditions).
;{{anchor|FASTOPEN}} {{mono|1=FASTOPEN}} {{nobold|(DR{{nbh}}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&nbsp;DOS [[FASTOPEN (DOS command)|FASTOPEN]] driver.
;{{anchor|FCBS}} {{mono|1=FCBS}} {{nobold|(DOS 3.0 and DR{{nbh}}DOS 3.31 and higher; OS/2<ref group="nb" name="since2"/><ref group="nb" name="pts"/>)}} : Specifies the number of cached [[File Control Block|FCBs]] that can be opened at once. (Under DR-DOS, {{mono|1=FCBS}} and {{mono|1=FILES}} dynamically share the same internal buffer.)
; {{anchor|FCBSHIGH}} {{mono|1=FCBSHIGH}} {{nobold|(MS-DOS 7.0<ref name="Microsoft_1995_CONFIG"/> and DR-DOS 7.02 and higher only<ref name="Paul_1997_OD-A3"/><ref name="Paul_2000_CONFIG"/>)}} : Same as {{mono|1=FCBS}}, but explicitly loads FCBs into upper memory.
;{{anchor|FILENAME}} {{mono|1=FILENAME}} {{nobold|(PTS-DOS only)}} : Boot manager.
;{{anchor|FILES}} {{mono|1=FILES}} {{nobold|(DOS 2.0 and DR{{nbh}}DOS 3.31 and higher; OS/2<ref group="nb" name="since2"/><ref group="nb" name="pts"/>)}} : Specifies the number of files that can be opened at once.
;{{anchor|FILESHIGH}} {{mono|1=FILESHIGH}} {{nobold|(MS-DOS 7.0<ref name="Microsoft_1995_CONFIG"/> and DR-DOS 7.02 and higher<ref name="Paul_1997_OD-A3"/><ref name="Paul_2000_CONFIG"/> and FreeDOS only)}} : Same as {{mono|1=FILES}}, but explicitly loads file handles into upper memory.
;{{anchor|FORCE}} {{mono|1=FORCE}} {{nobold|(PTS-DOS only)}} : Include execution of specified CONFIG.SYS subsections. See {{mono|1=IGNORE}}.

=== G{{nbnd}}I ===
;{{anchor|GETKEY}} {{mono|1=GETKEY}} {{nobold|(DR&nbsp;DOS 6.0 and higher only)}} : Waits for key (or timeout) and sets error level to its ASCII code (or 1024 on timeout).
;{{anchor|GOTO}} {{mono|1=GOTO}} {{nobold|(DR&nbsp;DOS 5.0 and higher only)}} : Continues CONFIG.SYS processing at specified label.
;{{anchor|GOSUB}} {{mono|1=GOSUB}} {{nobold|(DR&nbsp;DOS 6.0 and higher only)}} : Continues nested CONFIG.SYS processing at specified label, with {{mono|1=RETURN}} returning to old location.<ref name="Paul_1997_OD-A3"/>
;{{anchor|HIBUFFERS}} {{mono|1=HIBUFFERS}} {{nobold|(DR&nbsp;DOS 6.0 and higher only)}} : See {{mono|1=BUFFERSHIGH}} or {{mono|1=DOS=HIGH,UMB}} or {{mono|1=DOSDATA}}.
;{{anchor|HIDEVICE}} {{mono|1=HIDEVICE}} {{nobold|(DR&nbsp;DOS 5.0 and higher only)}} : See {{mono|1=DEVICEHIGH}}.
;{{anchor|HIDOS}} {{mono|1=HIDOS}} {{nobold|(DR&nbsp;DOS 5.0 and higher only)}} : See {{mono|1=DOS=HIGH,UMB}}.
;{{anchor|HIFCBS}} {{mono|1=HIFCBS}} {{nobold|(DR&nbsp;DOS 7.02 and higher,<ref name="Paul_1997_OD-A3"/><ref name="Paul_2000_CONFIG"/> EDR-DOS 7.01.07 and DRMK only)}} : See {{mono|1=FCBSHIGH}} or {{mono|1=DOSDATA}}.
;{{anchor|HIFILES}} {{mono|1=HIFILES}} {{nobold|(DR&nbsp;DOS 7.02 and higher,<ref name="Paul_1997_OD-A3"/><ref name="Paul_2000_CONFIG"/> EDR-DOS 7.01.07 and DRMK only)}} : See {{mono|1=FILESHIGH}} or {{mono|1=DOSDATA}}.
;{{anchor|HIINSTALL}} {{mono|1=HIINSTALL}} {{nobold|(DR&nbsp;DOS 5.0 and higher only)}} : See {{mono|1=INSTALLHIGH}}.
;{{anchor|HIINSTALLLAST}} {{mono|1=HIINSTALLLAST}} {{nobold|(EDR-DOS 7.01.07 and DRMK only)}} : Installs a TSR program into memory, like {{mono|1=HIINSTALL}}, but installs after the DOS data segment relocation. Compare also: [[INSTCDEX]].
;{{anchor|HILASTDRIVE}} {{mono|1=HILASTDRIVE}} {{nobold|(DR-DOS 7.02 and higher,<ref name="Paul_1997_OD-A3"/> EDR-DOS 7.01.07 and DRMK only)}} : See {{mono|1=LASTDRIVEHIGH}} or {{mono|1=DOS=UMB}} or {{mono|1=DOSDATA}}.
;{{anchor|HISHELL}} {{mono|1=HISHELL}} {{nobold|(DR-DOS 7.02 and higher only)}} : See {{mono|1=SHELLHIGH}}.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2000_CONFIG"/><ref name="Paul_2004_YESCHAR"/>
;{{anchor|HISTACKS}} {{mono|1=HISTACKS}} {{nobold|(DR-DOS 7.02 and higher,<ref name="Paul_1997_OD-A3"/> EDR-DOS 7.01.07 and DRMK only)}} : See {{mono|1=STACKSHIGH}} or {{mono|1=DOSDATA}}.
;{{anchor|HISTORY}} {{mono|1=HISTORY}} {{nobold|(DR&nbsp;DOS 3.41<!-- possibly 3.40+, definitely not 3.31 --> and higher only)}} : Enables and configures console and command line history buffer and extended pattern search functionality.
;{{anchor|HMAREA}} {{mono|1=HMAREA}} {{nobold|(PTS-DOS only)}} : Specifies the address of the HMA segment.
;{{anchor|IDLEHALT}} {{mono|1=IDLEHALT}} {{nobold|(FreeDOS only)}} : Configures HLT energy saving.
;{{anchor|IDTCHK}} {{mono|1=IDTCHK}} {{nobold|(PTS-DOS only)}} : Specifies if the system should check for boot sector viruses.
;{{anchor|IFS}} {{mono|1=IFS}} {{nobold|(MS-DOS 4.00-4.01 only, ignored under DR-DOS 7.02 and higher; OS/2<ref group="nb" name="since2"/>)}} : Loads [[installable file system]]s.
;{{anchor|IGNORE}} {{mono|1=IGNORE}} {{nobold|(PTS-DOS only)}} : Exclude execution of specified CONFIG.SYS subsections. See {{mono|1=FORCE}}.
;{{anchor|IOPL}} {{mono|1=IOPL}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Specifies programs (which would normally run at the CPU's [[IOPL]] [[Ring 3 (computer security)|ring 3]]) which should be allowed to run at [[ring 2 (computer security)|ring 2]] in order to directly access the hardware for I/O.
;{{anchor|INCLUDE}} {{mono|1=INCLUDE}} {{nobold|(DOS 6.0 and higher, not DR-DOS, not FreeDOS)}} : Include directives from another menu block. (Can be emulated using {{mono|1=GOSUB}} and {{mono|1=RETURN}} under DR-DOS.)
;{{anchor|INSERT}} {{mono|1=INSERT}} {{nobold|(DR-DOS 7.02 and higher only)}} : Specifies whether the keyboard {{keypress|Insert}} mode status is turned on or off.<ref name="Paul_1997_OD-A3"/>
;{{anchor|INSTALL}} {{mono|1=INSTALL}} {{nobold|(DOS 4.0 and DR DOS 3.41<!-- or earlier? but not in 3.31 --> and higher<ref group="nb" name="pts"/>)}} : Installs a TSR program into memory.<ref name="Paul_1997_NWDOSTIP"/><ref name="4DOS_8.00_HELP"/>
;{{anchor|INSTALLHIGH}} {{mono|1=INSTALLHIGH}} {{nobold|(DOS 6.0 and DR&nbsp;DOS 6.0 and higher<ref group="nb" name="pts"/>)}} : Installs a TSR program into upper memory. (Same as {{mono|1=HIINSTALL}} in DR DOS 5.0.)
;{{anchor|INSTALLLAST}} {{mono|1=INSTALLLAST}} {{nobold|(EDR-DOS 7.01.07 and DRMK only)}} : Installs a TSR program into memory, like {{mono|1=INSTALL}}, but installs after the DOS data segment relocation. Compare also: [[INSTCDEX]].
;{{anchor|IRQPRIORITY}} {{mono|1=IRQPRIORITY}} {{nobold|(Embedded DOS 6-XL only)}} : Rotates PIC controller interrupt priorities so that specified number gets the highest priority
=== K{{nbnd}}M ===
;{{anchor|KEYBOARD}} {{mono|1=KEYBOARD}} {{nobold|(PTS-DOS only)}} : Specifies the keyboard layout.
;{{anchor|KEYBUF}} {{mono|1=KEYBUF}} {{nobold|(FreeDOS only)}} : Specifies the address of the relocated keyboard buffer.
;{{anchor|LASTDRIVE}} {{mono|1=LASTDRIVE}} {{nobold|(DOS 3.0 and DOS&nbsp;Plus 2.1 with FIDDLOAD and DR&nbsp;DOS 3.31 and higher; OS/2<ref group="nb" name="since2"/><ref group="nb" name="pts"/>)}} : Specifies the maximum of drives that can be accessed.
;{{anchor|LASTDRIVEHIGH}} {{mono|1=LASTDRIVEHIGH}} {{nobold|(MS-DOS 7.0<ref name="Microsoft_1995_CONFIG"/> 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.
;{{anchor|LIBPATH}} {{mono|1=LIBPATH}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Specifies a list of search paths for DLLs.
;{{anchor|LOADFIX}} {{mono|1=LOADFIX}} {{nobold|(PTS-DOS only)}} : Specifies how old programs should be handled.
;{{anchor|LOCKS}} {{mono|1=LOCKS}} {{nobold|(PTS-DOS only)}} : Specifies number of file locks.
;{{anchor|LOGO}} {{mono|1=LOGO}} {{nobold|(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.
;{{anchor|LPT1}} {{mono|1=LPT1}} {{nobold|(DR-DOS 7.02 and higher only)}} : Defines count and logical order and configures I/O address and timeout for [[LPT1]]: device.<ref name="Paul_1997_OD-A3"/>
;{{anchor|LPT2}} {{mono|1=LPT2}} {{nobold|(DR-DOS 7.02 and higher only)}} : Defines count and logical order and configures I/O address and timeout for [[LPT2]]: device.<ref name="Paul_1997_OD-A3"/>
;{{anchor|LPT3}} {{mono|1=LPT3}} {{nobold|(DR-DOS 7.02 and higher only)}} : Defines count and logical order and configures I/O address and timeout for [[LPT3]]: device.<ref name="Paul_1997_OD-A3"/>
;{{anchor|LPT4}} {{mono|1=LPT4}} {{nobold|(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.
;{{anchor|MAXWAIT}} {{mono|1=MAXWAIT}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Specifies time before a waiting process gets a higher priority.
;{{anchor|MEMMAN}} {{mono|1=MEMMAN}} {{nobold|(OS/2<!-- at least since 1.3 --> only)}} : Configures memory allocation strategy
;{{anchor|MEMORY}} {{mono|1=MEMORY}} {{nobold|(PTS-DOS only)}} : Specifies the default DOS memory allocation strategy.
;{{anchor|MENU}} {{mono|1=MENU}} {{nobold|(FreeDOS only)}} : Defines menu options.
;{{anchor|MENUCOLOR}} {{mono|1=MENUCOLOR}} {{nobold|(DOS 6.0 and higher, not DR&nbsp;DOS, not FreeDOS)}} : Specifies menu colors. (Can be emulated using {{mono|1=ECHO}} under DR-DOS.)
;{{anchor|MENUDEFAULT}} {{mono|1=MENUDEFAULT}} {{nobold|(DOS 6.0 and higher and FreeDOS, not DR&nbsp;DOS)}} : Specifies the default menu block. (Can be emulated using {{mono|1=TIMEOUT}} and {{mono|1=SWITCH}} under DR-DOS.)
;{{anchor|MENUITEM}} {{mono|1=MENUITEM}} {{nobold|(DOS 6.0 and higher, not DR&nbsp;DOS, not FreeDOS)}} : Specifies a menu block. (Can be emulated using {{mono|1=ECHO}} and {{mono|1=SWITCH}} under DR-DOS.)
;{{anchor|MULTITRACK}} {{mono|1=MULTITRACK}} {{nobold|(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.
;{{anchor|NEWFILE}} {{mono|1=NEWFILE}} {{nobold|(Datalight ROM-DOS only)}} : Continues CONFIG.SYS processing in new file (similar to DR-DOS [[#CHAIN|CHAIN]]) and optionally after loading a specific device driver and setting [[%NEWFILE%]] environment variable.<ref name="Datalight_2005_ROM-DOS"/>

=== N{{nbnd}}Q ===
;{{anchor|NOCHAR}} {{mono|1=NOCHAR}} {{nobold|(DR-DOS 7.02 and higher only)}} : Specifies the default No ({{keypress|N}}) character in Yes/No/Resume questions.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2000_CONFIG"/><ref name="Paul_2004_YESCHAR"/>)
;{{anchor|NUMLOCK}} {{mono|1=NUMLOCK}} {{nobold|(DOS 6.0 and Novell DOS 7 and higher)}} : Specifies whether the keyboard [[Num Lock|{{keypress|Num Lock}}]] status is turned on or off.
;{{anchor|ONERROR}} {{mono|1=ONERROR}} {{nobold|(DR&nbsp;DOS 6.0 and higher only)}} : Conditional execution depending on last return code/error status only, f.e. {{code|2=bat|ONERROR > 0 GOTO failload}} or {{code|2=dosbatch|1=ONERROR > 10 ONERROR <> 17 ONERROR <= 30 ECHO Error 11-16 or 18-30 occurred}}.<ref name="Paul_1997_NWDOSTIP"/>
;{{anchor|PAUSE}} {{mono|1=PAUSE}} {{nobold|(PTS-DOS only)}} : Similar to {{mono|1=ECHO}} and {{mono|1=GETKEY}} under DR-DOS, displays a text and waits for a key press.
;{{anchor|PAUSEONERROR}} {{mono|1=PAUSEONERROR}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Specifies if user must acknowledge errors in CONFIG.SYS.
;{{anchor|PRINTMONBUFSIZE|PRINTMONBUFFER}} {{mono|PRINTMONBUFSIZE}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Configures buffer size for LPT1, LPT2, LPT3.
;{{anchor|PC}} {{mono|1=PC}} {{nobold|(PTS-DOS only)}} : Conditional execution on PC-compatible machines only.
;{{anchor|PRIORITY}} {{mono|1=PRIORITY}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Configures priority scheduler.
;{{anchor|PRIORITY_DISK_IO}} {{mono|PRIORITY_DISK_IO}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Configures priority of programs using disk I/O.
;{{anchor|PRN}} {{mono|1=PRN}} {{nobold|(DR-DOS 7.02 and higher only)}}: Changes internal default printer device driver ({{mono|1=LPT1}} to {{mono|1=LPT3}}, or even {{mono|1=LPT4}}) for PRN device.<ref name="Paul_1997_OD-A3"/>
;{{anchor|PROTECTONLY}} {{mono|1=PROTECTONLY}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Specifies if DOS programs can be run or not.
;{{anchor|PROTSHELL}} {{mono|1=PROTSHELL}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Loads user interface.
;{{anchor|PS1}} {{mono|PS1}} {{nobold|(PTS-DOS only)}} : Conditional execution on [[IBM PS/1|PS/1]]-compatible machines only.
;{{anchor|PS2}} {{mono|PS2}} {{nobold|(PTS-DOS only)}} : Conditional execution on [[IBM PS/2|PS/2]]-compatible machines only.
;{{anchor|QUIET}} {{mono|1=QUIET}} {{nobold|(PTS-DOS and DRMK only)}} : Mutes display output send to STDOUT.

=== R{{nbnd}}T ===
;{{anchor|REIPL}} {{mono|1=REIPL}} {{nobold|(OS/2 3.0 and higher only)}} : Specifies if system should reboot automatically on errors.
;{{anchor|REM}} {{mono|1=REM}} {{nobold|(DOS 4.0 and DR DOS 3.31 and higher;<ref name="Paul_2004_YESCHAR"/> ignored under PTS-DOS)}} : Allows comments in CONFIG.SYS.
;{{anchor|RESERVEDRIVELETTER}} {{mono|1=RESERVEDRIVELETTER}} {{nobold|(OS/2 3 FixPack 24 and higher only)}} : Specifies a drive letter not to be used up for local block device drivers.
;{{anchor|RESUMECHAR}} {{mono|1=RESUMECHAR}} {{nobold|(DR-DOS 7.02 and higher only)}}: Specifies the default Resume ({{keypress|R}}) character in Yes/No/Resume queries.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2004_YESCHAR"/>)
;{{anchor|RETURN}} {{mono|1=RETURN}} {{nobold|(DR{{nbh}}DOS 6.0 and higher only)}} : Returns nested CONFIG.SYS processing at previous location of {{mono|1=GOSUB}} or {{mono|1=SWITCH}} directive. An optional return code can be given, otherwise 0 is assumed.
;{{anchor|RMSIZE}} {{mono|1=RMSIZE}} {{nobold|(OS/2<ref group="nb" name="since2"/> only, ignored under DR-DOS 7.02 and higher)}} : Defines the real mode memory size.
;{{anchor|RUN}} {{mono|1=RUN}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Similar to {{mono|1=CALL}}, loads programs in CONFIG.SYS. Similar to {{mono|1=INSTALL}} under DOS and {{mono|1=CALL}} under OS/2, but loads programs in background concurrently.
;{{anchor|SAVENAME}} {{mono|1=SAVENAME}} {{nobold|(PTS-DOS only)}} : Specifies, if the first character of deleted files should be stored in the [[FAT SAVENAME|reserved area]] of directory entries in the [[File Allocation Table|FAT]] file system.
;{{anchor|SCREEN}} {{mono|1=SCREEN}} {{nobold|(FreeDOS and PTS-DOS only)}} : Similar to {{mono|1=VIDEOMODE}} under PTS-DOS, specifies the video mode to be used under FreeDOS. Under PTS-DOS, {{mono|1=SCREEN}} does not specify the video mode but screen access methods.
;{{anchor|SCROLLOCK}} {{mono|1=SCROLLOCK}} {{nobold|(DR-DOS 7.02 and higher only)}} : Specifies whether the keyboard [[Scroll Lock|{{keypress|Scroll Lock}}]] status is turned on or off.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2004_YESCHAR"/>)
;{{anchor|SET}} {{mono|1=SET}} {{nobold|(DOS 6.0 and DR{{nbh}}DOS 6.0 and higher; OS/2<ref group="nb" name="since2"/>)}} : Sets environment variables.
;{{anchor|SHELL}} {{mono|1=SHELL}} {{nobold|(DOS 2.0 and DR{{nbh}}DOS 3.31 and higher; OS/2<ref group="nb" name="since2"/><ref group="nb" name="pts"/>)}} : Loads the command interpreter shell.<ref name="Paul_2004_YESCHAR"/><ref name="Paul_2004_COMMAND"/>
;{{anchor|SHELLHIGH}} {{mono|1=SHELLHIGH}} {{nobold|(DR-DOS 7.02 and higher and PTS-DOS and FreeDOS only)}} : Same as {{mono|1=SHELL}}, but supports an additional {{mono|1=SIZE}} parameter to define the size of the pre-allocation for COMMAND.COM to relocate its resident portion into the HMA (with <code>/MH</code>). 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="Paul_2000_CONFIG"/><ref name="4DOS_8.00_HELP"/><ref name="Paul_2004_YESCHAR"/>
;{{anchor|SHIFTSTATE}} {{mono|1=SHIFTSTATE}} {{nobold|(PTS-DOS only)}} : Specifies the state of the keyboard modifiers like Shift Lock, Num Lock, Scroll Lock or Insert mode.
;{{anchor|SHUTDOWN}} {{mono|1=SHUTDOWN}} {{nobold|(PTS-DOS only)}} : Specifies if files should be closed on {{keypress|Ctrl|Alt|Del}}.
;{{anchor|SOFTREBOOT}} {{mono|1=SOFTREBOOT}} {{nobold|(PTS-DOS only)}} : Specifies if POST should be skipped on reboots.
;{{anchor|STACK}} {{mono|1=STACK}} {{nobold|(ignored under DR{{nbh}}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.
;{{anchor|STACKS}} {{mono|1=STACKS}} {{nobold|(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.
;{{anchor|STACKSIZE}} {{mono|1=STACKSIZE}} {{nobold|(Embedded DOS 6-XL only)}} : Default stack size allocated for new threads.
;{{anchor|STACKSHIGH}} {{mono|1=STACKSHIGH}} {{nobold|(MS-DOS 7.0<ref name="Microsoft_1995_CONFIG"/> and DR-DOS 7.02 and higher,<ref name="Paul_1997_OD-A3"/> and FreeDOS only)}} : Same as {{mono|1=STACKS}}, but explicitly loads buffers into upper memory.
;{{anchor|STORAGE}} {{mono|1=STORAGE}} {{nobold|(PTS-DOS only)}} : Boot manager.
;{{anchor|STRING}} {{mono|1=STRING}} {{nobold|(MS-DOS 3.0 only, ignored under DR-DOS 7.02 and higher)}} : Internal use.
;{{anchor|STUBA20}} {{mono|STUBA20}} {{nobold|(PTS-DOS only)}} : Specifies how XMS [[A20 gate]] control should work.
;{{anchor|SUBMENU}} {{mono|1=SUBMENU}} {{nobold|(DOS 6.0 and higher, not DR{{nbh}}DOS, not FreeDOS)}} : Specifies a submenu block. (Can be emulated using {{mono|1=CLS}}, {{mono|1=ECHO}} and {{mono|1=SWITCH}} under DR-DOS.)
;{{anchor|SUPPRESSPOPUPS}} {{mono|1=SUPPRESSPOPUPS}} {{nobold|(OS/2 3.0 and higher only)}} : Specifies a drive where to log error information instead of displaying a textmode popup screen.
;{{anchor|SWAPPATH}} {{mono|1=SWAPPATH}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Specifies swap file path.
;{{anchor|SWITCH}} {{mono|1=SWITCH}} {{nobold|(DR DOS 6.0 and higher only)}} : Conditionally continues nested CONFIG.SYS processing at one of the specified labels depending on keys pressed, with {{mono|1=RETURN}} returning to old location.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2000_CONFIG"/><ref name="Paul_2004_YESCHAR"/>
;{{anchor|SWITCHAR}} {{mono|1=SWITCHAR}} {{nobold|(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"/>
;{{anchor|SWITCHES}} {{mono|1=SWITCHES}} {{nobold|(DOS 4.0 and Novell DOS 7 and higher; ignored under PTS-DOS)}} : Specifies special options.<ref name="Paul_2004_YESCHAR"/><ref name="Paul_1997_OD-A3"/>
;{{anchor|SXFAKEHWFPU}} {{mono|1=SXFAKEHWFPU}} {{nobold|(OS/2 Warp 4 FixPak 1 (and higher) only)}} : Specifies if a fix for a FPU rounding bug should be activated or not.
;{{anchor|SYSBOOT}} {{mono|1=SYSBOOT}} {{nobold|(PTS-DOS only)}} : Specifies file name of alternative DOS operating systems to boot.
;{{anchor|SYSGEN}} {{mono|1=SYSGEN}} {{nobold|(PTS-DOS only)}} : Configures the location of the various DOS parts in memory.
;{{anchor|SYSLOAD}} {{mono|1=SYSLOAD}} {{nobold|(PTS-DOS only)}} : Load system from alternative disk area.
;{{anchor|SYSTEMPOOL}} {{mono|1=SYSTEMPOOL}} {{nobold|(Embedded DOS 6-XL only)}} : Size of system memory pool from which the system dynamically allocates for various purposes
;{{anchor|SYSTOUMB}} {{mono|1=SYSTOUMB}} {{nobold|(PTS-DOS only)}} : Specifies if DOS data and code should be loaded into UMBs.
;{{anchor|THREADS}} {{mono|1=THREADS}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Specifies number of concurrent threads.
;{{anchor|TIMEOUT}} {{mono|1=TIMEOUT}} {{nobold|(DR{{nbh}}DOS 6.0 and higher and PTS-DOS only)}} : Specifies the timeouts in CONFIG.SYS single-stepping and with {{mono|1=SWITCH}}, {{mono|1=GETKEY}} and {{mono|1=?}}, and the default answers for Yes/No queries and {{mono|1=SWITCH}} selections.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2000_CONFIG"/><ref name="Paul_2004_YESCHAR"/> PTS-DOS only supports the timeout value.
;{{anchor|TIMESLICE}} {{mono|1=TIMESLICE}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Configures minimum and maximum time slices for scheduler.
;{{anchor|TMPEXT}} {{mono|1=TMPEXT}} {{nobold|(PTS-DOS only)}} : Specifies the file extension for temporary files.
;{{anchor|TRACE}} {{mono|1=TRACE}} {{nobold|(DR-DOS 7.02 and higher and PTS-DOS only; OS/2<ref group="nb" name="since2"/>)}} : Globally or locally enables or disables CONFIG.SYS (and AUTOEXEC.BAT) single-stepping execution.<ref name="Paul_2004_YESCHAR"/><ref name="Paul_1997_OD-A3"/> The functionality under OS/2 differs significantly from that under DOS.
;{{anchor|TRACEBUF}} {{mono|1=TRACEBUF}} {{nobold|(OS/2<ref group="nb" name="since2"/> only)}} : Specifies size of {{mono|1=TRACE}} log buffer.
;{{anchor|TRAPDUMP}} {{mono|1=TRAPDUMP}} {{nobold|(OS/2 3.0<!-- 4.0? --> and higher only)}} : Logs detailed error information.

=== U{{nbnd}}Z ===
;{{anchor|UMB}} {{mono|1=UMB}} {{nobold|(Embedded DOS<ref group="nb" name="embed"/> only)}} : Configures DOS management to use a specific segment as UMB memory.
;{{anchor|UMBSRV}} {{mono|1=UMBSRV}} {{nobold|(PTS-DOS only)}} : Configures the UMB server used.
;{{anchor|USERAM}} {{mono|1=USERAM}} {{nobold|(PTS-DOS only)}} : Specifies the address ranges used as UMB RAM.
;{{anchor|VERIFY}} {{mono|1=VERIFY}} {{nobold|(DR-DOS 7.02 and higher<ref name="Paul_1997_OD-A3"/> and Embedded DOS<ref group="nb" name="embed"/> only)}} : Enables or disables disk write verification.
;{{anchor|VERSION}} {{mono|1=VERSION}} {{nobold|(FreeDOS, Embedded DOS,<ref group="nb" name="embed"/> and EDR-DOS 7.01.07 only)}} : Specifies the DOS version (and optionally the true DOS version) to be reported to programs.
;{{anchor|VGASCREEN}} {{mono|1=VGASCREEN}} {{nobold|(PTS-DOS only)}} : Configures VGA display status.
;{{anchor|VIDEOMODE}} {{mono|1=VIDEOMODE}} {{nobold|(PTS-DOS only)}} : Similar to {{mono|1=SCREEN}} under FreeDOS, specifies current video mode.
;{{anchor|VIRTDMA}} {{mono|1=VIRTDMA}} {{nobold|(PTS-DOS only)}} : Specifies if virtual DMA can be used.
;{{anchor|VME}} {{mono|1=VME}} {{nobold|(OS/2<!-- possibly only late versions --> only)}} : Specifies if the processor's [[Virtual Mode Extensions]] (VME) should be deactivated or not.
;{{anchor|VXD}} {{mono|1=VXD}} {{nobold|(PTS-DOS only)}} : Configures VxD driver for Windows.
;{{anchor|WINDOWS}} {{mono|1=WINDOWS}} {{nobold|(PTS-DOS only)}} : Configures system support for Windows.
;{{anchor|XBDA}} {{mono|1=XBDA}} {{nobold|(EDR-DOS 7.01.07 and DRMK only)}} : Configures the relocation of the [[Extended BIOS data area]] (XBDA)
;{{anchor|XT}} {{mono|1=XT}} {{nobold|(PTS-DOS only)}} : Conditional execution on XT-compatible machines only.
;{{anchor|YEAR2000}} {{mono|YEAR2000}} {{nobold|(DR-DOS 7.02 and higher only)}} : Configures the built-in [[Year 2000 problem|Year 2000]] support.
;{{anchor|YESCHAR}} {{mono|1=YESCHAR}} {{nobold|(PalmDOS 1.0, DR DOS 6.0 updates and Novell DOS 7 and higher only)}} : Specifies the default Yes ({{keypress|Y}}) character in Yes/No/Resume queries.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2004_YESCHAR"/>
;{{anchor|ZOMBIEDRV}} {{mono|1=ZOMBIEDRV}} {{nobold|(PTS-DOS only)}} : Configures deletion tracking.