Editing CONFIG.SYS

{{Short description|Primary system configuration file for DOS}}
{{Use dmy dates|date=April 2019|cs1-dates=y}}
{{Use list-defined references|date=January 2022}}
{{Redirect-distinguish-for|SHELL|SHELL model||Shell (disambiguation)}}
'''CONFIG.SYS''' is the primary [[configuration file]] for the [[DOS]] and [[OS/2]] [[operating system]]s. It is a special [[ASCII]] text file that contains user-accessible setup or configuration directives evaluated by the operating system's [[DOS BIOS]] (typically residing in [[IBMBIO.COM]] or [[IO.SYS]]) during boot. CONFIG.SYS was introduced with DOS 2.0.<ref group="nb" name="NB_Durango_CONFIG.SYS"/>

== Usage ==
The directives in this file configure DOS for use with devices and applications in the system. The CONFIG.SYS directives also set up the memory managers in the system. After processing the CONFIG.SYS file, DOS proceeds to load and execute the [[command-line interpreter|command shell]] specified in the <kbd>SHELL</kbd> line of CONFIG.SYS, or [[COMMAND.COM]] if there is no such line. The command shell in turn is responsible for processing the [[AUTOEXEC.BAT]] file.

CONFIG.SYS is composed mostly of <kbd>[[key=value pair|name=value]]</kbd> directives which look like variable assignments. In fact, these will either define some tunable parameters often resulting in reservation of memory, or load files, mostly [[device driver]]s and [[terminate-and-stay-resident program]]s (TSRs), into memory.

In DOS, CONFIG.SYS is located in the [[root directory]] of the drive from which the system was booted.

The filename is also used by {{ill|Disk Control Program|de}} (DCP), an MS-DOS derivative by the former East-German [[VEB Robotron]].<ref name="DCP_2016"/>

Some versions of DOS will probe for alternative filenames taking precedence over the default CONFIG.SYS filename if they exist:

While older versions of [[Concurrent DOS]] 3.2 to 4.1<!-- in 1985/1986 --> did not support CONFIG.SYS files at all, later versions<!-- since when exactly? --> of [[Concurrent DOS 386]] and [[Concurrent DOS XM]]<!-- since 1987. What about Concurrent DOS 286? -->, as well as [[Multiuser DOS]], [[Datapac System Manager|System Manager]] and [[REAL/32]] will probe for '''CCONFIG.SYS'''<!-- really CCONFIG.SYS, not CCONFIG.INI as under CCI Multiuser DOS? --> (with "C" derived from "Concurrent") instead of CONFIG.SYS. Some versions of Multiuser&nbsp;DOS use a filename of '''CCONFIG.INI''' instead,<ref name="CCI_1997_PRINTDOC"/><ref name="CCI_1997_HELP"/> whereas <!-- probably other Multiuser DOS issues as well, and -->REAL/32<!-- 7.90--> is known to look for '''MCONFIG.SYS'''. These operating systems support many additional and different configuration settings (like <kbd>INIT_INSTALL</kbd>) not known under MS-DOS/PC&nbsp;DOS, but they are stored in the binary repository named '''CCONFIG.BIN''' rather than in '''CCONFIG.INI'''.<ref name="CCI_1997_PRINTDOC"/><ref name="CCI_1997_HELP"/> Both files are typically modified through a configuration utility named <kbd>CONFIG.EXE</kbd> only.<!-- This holds true at least for CCI Multiuser DOS 7.22 Gold. --><ref name="CCI_1997_PRINTDOC"/><ref name="CCI_1997_HELP"/>

Under [[DR&nbsp;DOS]]&nbsp;3.31, [[PalmDOS]]&nbsp;1.0, [[Novell&nbsp;DOS]]&nbsp;7, [[OpenDOS]]&nbsp;7.01, and DR-DOS&nbsp;7.02 and higher, a file named '''DCONFIG.SYS''' (with "D" derived from "DR&nbsp;DOS"), if present, will take precedence over CONFIG.SYS.<ref name="Paul_1997_NWDOSTIP"/><ref name="Caldera_1998_USER"/><ref name="Paul_2004_CHAIN"/><ref name="Paul_2017_DR"/> Since DR&nbsp;DOS&nbsp;6.0 this was used in conjunction with disk compression software, where the original boot drive&nbsp;C: would become drive&nbsp;D: after loading the compression driver (and the "D" in the file name came in handy as well), but it is commonly used to help maintain multiple configuration files in multi-boot scenarios.
In addition to this, OpenDOS&nbsp;7.01 and DR-OpenDOS&nbsp;7.02 will look for a file named '''ODCONFIG.SYS''',<ref name="Paul_1997_OD-A3"/><ref name="Paul_2001_NWDOSTIP"/><ref name="Paul_2004_CHAIN"/> whereas some issues of DR-DOS&nbsp;7.02 and higher will instead also look for '''DRCONFIG.SYS'''.<ref name="Paul_2004_CHAIN"/>
Further, under DR&nbsp;DOS&nbsp;6.0 and higher, the <code>SYS&nbsp;/DR:ext</code> command can be used to change the default file extensions.<ref name="Paul_1997_OD-A3"/><ref name="Novell_1993_LOADER"/><ref name="Paul_2017_DR"/> For example, with <code>SYS&nbsp;/L&nbsp;/DR:703</code> the written [[Volume Boot Record]] would look for a renamed and modified IBMBIO.703 system file (instead of the default [[IBMBIO.COM]]) and the IBMBIO.703 would look for IBMDOS.703 and [D]CONFIG.703 (instead of [[IBMDOS.COM]] and [D]CONFIG.SYS), so that multiple parallel sets of files can coexist in the same root directory and be selected via a boot-loader like LOADER, supplied with Multiuser DOS and DR-DOS 7.02/7.03.<ref name="Paul_1997_NWDOSTIP"/> The <kbd>SHELL</kbd> directive is enhanced to provide means to specify alternative AUTOEXEC.BAT files via <kbd>/P[:filename.ext]</kbd> and in this specific scenario, COMMAND.COM will accept file extensions other than "<code>.BAT</code>" as well (both features are also supported by [[4DOS]]).<ref name="4DOS_8.00_HELP"/> Under DR&nbsp;DOS&nbsp;6.0 and higher, the CONFIG.SYS directive <kbd>CHAIN=filespec</kbd> can be used to continue processing in the named file, which does not necessarily need to reside in the root directory of the boot drive.<ref name="Paul_1997_NWDOSTIP"/><ref name="Paul_2004_CHAIN"/> DR-DOS&nbsp;7.02 and higher optionally support an additional parameter as in <kbd>CHAIN=filespec,label</kbd> to jump to a specific <kbd>:label</kbd> in the given file.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2001_NWDOSTIP"/><ref name="Paul_2004_CHAIN"/>
DR-DOS 7.03 and higher support a new <code>SYS&nbsp;/A</code> parameter in order to copy the corresponding CONFIG.SYS and AUTOEXEC.BAT files along with the system files.<ref name="Paul_2017_DR"/>

[[FreeDOS]] implements a similar feature with its '''FDCONFIG.SYS''' configuration file. [[RxDOS]]&nbsp;7.24 and higher use '''RXCONFIG.SYS''' instead.<ref name="RxDOS724"/> [[PTS-DOS]] uses '''CONFIG.PTS'''.

Both CONFIG.SYS and AUTOEXEC.BAT can be found included in the [[Root directory|root folder]] of [[Windows&nbsp;95]], and [[Windows&nbsp;98]] boot drives, as they are based on DOS. Typically, these files are left empty, with no content.

[[Windows&nbsp;Me]] does not even parse the CONFIG.SYS file during the Windows boot process,<ref name="Microsoft_2000_Windows-ME"/> loading [[environment variable]]s from the [[Windows Registry]] instead:
:
: <kbd>HKLM\System\CurrentControlSet\Control\SessionManager\Environment</kbd>

Under [[FlexOS]]<!-- at least in FlexOS 286 1.13 as of 1986/1987 -->, CONFIG.SYS is a binary file defining the resource managers and device drivers loaded.

== Example ==

An example CONFIG.SYS for MS-DOS 5:
<syntaxhighlight lang="ini" line="1">
DOS=HIGH,UMB
DEVICE=C:\DOS\HIMEM.SYS
DEVICE=C:\DOS\EMM386.EXE RAM
DEVICEHIGH=C:\DOS\ANSI.SYS
FILES=30
SHELL=C:\DOS\COMMAND.COM C:\DOS /E:512 /P
</syntaxhighlight>

== 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.

== Issues ==
[[File:PC-MOS-386 boot screen.jpg|thumb|[[PC-MOS]] detecting a missing {{code|CONFIG.SYS}} on startup]] 
The system can still boot if this file is missing or corrupted. However, this file, along with [[AUTOEXEC.BAT]], is essential for the complete bootup process to occur with the DOS operating system. These files contain information that is used to customize the operating system for personal use. They also contain the requirements of different software application packages. A DOS system would require troubleshooting if either of these files became damaged or corrupted.

If CONFIG.SYS does not contain a <kbd>SHELL</kbd> directive (or the file is corrupt or missing), DOS typically searches for COMMAND.COM in the root directory of the boot drive.<ref name="Paul_2004_YESCHAR"/> If this is not found, versions of DOS before 6.0 will not start up. MS-DOS 6.0/PC&nbsp;DOS 6.1 and Novell DOS 7<!-- not sure about PalmDOS right now --> and higher will instead display a prompt to enter the path and filename of a command processor. This recovery prompt is also displayed when the primary command processor is aborted due to faults or if it is exited deliberately.<ref name="Paul_1997_NWDOSTIP"/> (In the case of COMMAND.COM, the internal <code>EXIT</code> command is disabled only when the shell was started with <code>/P</code>.) This also provides limited means to replace the shell at [[runtime (program lifecycle phase)|runtime]] without having to reboot the system.
Since the MS-DOS 7.0 and higher COMMAND.COM executable is incompatible with DR-DOS,<ref name="Paul_2004_COMMAND"/> but typically resides in the root of drive C: in dual-boot scenarios with DR-DOS, DR-DOS 7.02 and higher no longer allow to bypass <kbd>SHELL</kbd> directives in ({{keypress|Ctrl}}+){{keypress|F5}}/{{keypress|F7}}/{{keypress|F8}} "skip"/"trace"/"step" modes.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2004_YESCHAR"/><ref name="Paul_2004_COMMAND"/> (Some later issues added ({{keypress|Ctrl}}+){{keypress|F6}} to reinvoke the former {{keypress|F5}} "skip" behaviour in order to allow recovery from problems with invalid <kbd>SHELL</kbd> arguments as well.<ref name="Paul_2004_YESCHAR"/>) Also, if no <kbd>SHELL</kbd> directive could be found when skipping CONFIG.SYS processing via ({{keypress|Ctrl}}+){{keypress|F5}} (and also with ({{keypress|Ctrl}}+){{keypress|F7}}/{{keypress|F8}}, when the default file extension has been changed with <code>SYS /DR:ext</code>),<ref name="Paul_2017_DR"/> the user is prompted to enter a valid shell file name ''before'' trying to load COMMAND.COM from the root.<ref name="Paul_1997_OD-A3"/><ref name="Paul_2004_COMMAND"/> Pressing {{keypress|ENTER}} without specifying a file will assume the former default.<ref name="Paul_1997_OD-A3"/>

Depending on the version, the size of the CONFIG.SYS file is limited to a few kilobytes under MS-DOS/PC&nbsp;DOS (up to 64&nbsp;KB in most recent versions), whereas the file's size is unlimited<!-- only limited by the file system --> under DR-DOS.<ref name="Paul_1997_NWDOSTIP"/><ref name="Paul_2004_YESCHAR"/> This is because the former operating systems (since DOS 3.0<ref name="Ernst_1987_DRIVER"/>) will compile the file into some tokenized in-memory representation<ref name="Ernst_1987_DRIVER"/> before they sort and regroup the directives to be processed in a specific order (with device drivers always being loaded before TSRs), whereas DR-DOS interprets the file and executes most directives line-by-line, thereby giving full control over the load order of drivers and TSRs via <kbd>DEVICE</kbd> and <kbd>INSTALL</kbd> (for example to solve load order conflicts or to load a program debugger before a device driver to be debugged)<ref name="Paul_1997_OD-A3"/><ref name="Paul_2004_YESCHAR"/> and allowing to adapt the user interaction and change the flow through the file based on conditions like processor types installed, any type of keys pressed, load or input errors occurring, or return codes given by loaded software.<ref name="Paul_1997_NWDOSTIP"/><ref name="Paul_1997_OD-A3"/> This becomes particularly useful since <kbd>INSTALL</kbd> can also be used to run non-resident software under DR-DOS, so that temporary external programs can be integrated into the CONFIG.SYS control flow.<ref name="Paul_1997_NWDOSTIP"/><ref name="4DOS_8.00_HELP"/><ref name="Paul_1997_OD-A3"/>

In MS-DOS/PC&nbsp;DOS 2.0 through 4.01, the length of the <kbd>SHELL</kbd> line was limited to 31 characters, whereas up to 128 characters are possible in later versions.<ref name="Paul_1997_NWDOSTIP"/><ref name="4DOS_8.00_HELP"/> DR-DOS even accepts up to 255 characters.<ref name="Paul_1997_NWDOSTIP"/><ref name="4DOS_8.00_HELP"/> CONFIG.SYS directives do not accept [[long filename]]s.

== Dual booting DOS and Windows 9x ==
When installing [[Windows&nbsp;95]] over a preexisting DOS/Windows install, CONFIG.SYS and AUTOEXEC.BAT are renamed to '''CONFIG.DOS''' and AUTOEXEC.DOS. This is intended to ease dual booting between Windows&nbsp;9x and DOS. When booting into DOS, they are temporarily renamed CONFIG.SYS and AUTOEXEC.BAT. Backups of the Windows&nbsp;95 versions are made as '''CONFIG.W40''' and AUTOEXEC.W40 files.

When Caldera DR-DOS 7.02/7.03 is installed on a system already containing Windows&nbsp;95, Windows' CONFIG.SYS and AUTOEXEC.BAT retain those names. DR-DOS' startup files are installed as DCONFIG.SYS (a name already used in earlier versions of DR DOS) and AUTODOS7.BAT.<ref name="Caldera_1998_USER"/>

== OS/2 / Windows NT ==
[[OS/2]] uses the CONFIG.SYS file extensively for setting up its configuration, drivers and environment before the graphical part of the system loads.

In the OS/2 subsystem of [[Windows NT]], what appeared as CONFIG.SYS to OS/2 programs was actually stored in the registry.

There are many undocumented or poorly documented CONFIG.SYS directives used by OS/2.<ref name="Childs_1995_OS2"/>

CONFIG.SYS continues to be used by the OS/2 derivatives [[eComStation]]<ref name="ecom_2001"/> and [[ArcaOS]].<ref name="ArcaOS_2020"/>

== See also ==
* [[IBMBIO.COM]] / [[IO.SYS]]
* [[IBMDOS.COM]] / [[MSDOS.SYS]]
* [[CONFIG (environment variable)]]
* [[AUTOEXEC.BAT]]
* [[COMMAND.COM]]
* [[List of DOS commands]]

== Notes ==
{{Reflist|group="nb"|refs=
<ref group="nb" name="NB_Durango_CONFIG.SYS">The filename of the DOS configuration file <code>CONFIG.SYS</code> was derived from an identically named file used by the operating system [[Durango DX-85M|DX-85M]] for the [[Durango F-85]] family of computers introduced in 1978 - five years before the advent of [[MS-DOS 2.0]]/[[PC DOS 2.0]] in 1983. Both files are text files and use various directives to configure the system and load drivers, however, the syntax differs.</ref>
}}

== References ==
{{Reflist|refs=
<ref name="Paul_1997_NWDOSTIP">{{cite book |title=NWDOS-TIPs &mdash; Tips & Tricks rund um Novell DOS 7, mit Blick auf undokumentierte Details, Bugs und Workarounds |language=de |trans-title=Tips & tricks for Novell DOS 7, with a focus on undocumented details, bugs and workarounds |series=MPDOSTIP |author-first=Matthias R. |author-last=Paul |date=1997-07-30 |edition=3 |url=http://www.antonis.de/dos/dos-tuts/mpdostip/html/nwdostip.htm |access-date=2012-01-11 |url-status=dead |archive-url=https://web.archive.org/web/20161105172944/http://www.antonis.de/dos/dos-tuts/mpdostip/html/nwdostip.htm |archive-date=5 November 2016 }} (NB. NWDOSTIP.TXT is a comprehensive work on [[Novell DOS 7]] and [[OpenDOS 7.01]], including the description of many undocumented features and internals. It is part of the author's yet larger MPDOSTIP.ZIP collection maintained up to 2001 and distributed on many sites at the time. The provided link points to a HTML-converted older version of the NWDOSTIP.TXT file.)</ref>
<ref name="Caldera_1998_USER">{{cite book |publisher=[[Caldera, Inc.]] |date=1998 |orig-year=1993, 1997 |title=Caldera DR-DOS 7.02 User Guide |url=http://www.drdos.net/documentation/usergeng/uglontoc.htm |url-status=dead |archive-url=https://web.archive.org/web/20161104235434/http://www.drdos.net/documentation/usergeng/uglontoc.htm |archive-date=2016-11-04}}</ref>
<ref name="Paul_1997_OD-A3">{{cite web |author-first=Matthias R. |author-last=Paul |title=Caldera OpenDOS 7.01/7.02 Update Alpha 3 IBMBIO.COM README.TXT |url=http://www.uni-bonn.de/~uzs180/download/ibmbioa3.zip |date=1997-10-02 |access-date=2009-03-29 |url-status=dead |archive-url=https://web.archive.org/web/20031004074600/http://www-student.informatik.uni-bonn.de/~frinke/ibmbioa3.zip |archive-date=2003-10-04}} [https://web.archive.org/web/20181225154705/http://mirror.macintosharchive.org/max1zzz.co.uk/+Windows%20&%20DOS/DOS/System/Novell/Support/Bins/Op702src.zip<!-- Op702src.zip is an unofficial renamed distribution of the ibmbioa3.zip file -->]</ref>
<ref name="Paul_2001_NWDOSTIP">{{cite book |title=NWDOS-TIPs &mdash; Tips & Tricks rund um Novell DOS 7, mit Blick auf undokumentierte Details, Bugs und Workarounds |language=de |trans-title=Tips & tricks for Novell DOS 7, with a focus on undocumented details, bugs and workarounds |series=MPDOSTIP |author-first=Matthias R. |author-last=Paul |date=2001-04-09 |edition=3}}</ref>
<ref name="Novell_1993_LOADER">{{cite web |title=Booting Multiple Operating Systems with the DR Multiuser DOS LOADER Utility |archive-url=https://web.archive.org/web/20120322220335/http://developer.novell.com/support/bullets/apr93.htm |archive-date=2012-03-22 |url=http://developer.novell.com/support/bullets/apr93.htm#articles |series=Volume 5, Number 4 |author-first=Mad |author-last=Poarch<!-- Director, Developer Support/Service --> |publisher=[[Novell]] |date=April 1993 |access-date=2013-06-28 |url-status=dead}}</ref>
<ref name="4DOS_8.00_HELP">{{cite book |title=4DOS 8.00 online help |title-link=4DOS 8.00 |author-first1=Hardin |author-last1=Brothers |author-first2=Tom |author-last2=Rawson |author-link2=Tom Rawson |author-first3=Rex C. |author-last3=Conn |author-link3=Rex C. Conn |author-first4=Matthias R. |author-last4=Paul |author-first5=Charles E. |author-last5=Dye |author-first6=Luchezar I. |author-last6=Georgiev |date=2002-02-27}}</ref>
<ref name="Microsoft_2000_Windows-ME">{{cite web |title=Understanding the Settings in the Windows Millennium Edition CONFIG.SYS File |date=2007-01-29 |orig-year=2000 |version=Revision 1.2 |id=KB274646. Q274646 |publisher=[[Microsoft]] |access-date=2006-10-16 |url=http://support.microsoft.com/kb/q274646/ |url-status=dead |archive-url=https://archive.today/20120723153210/http://support.microsoft.com/kb/q274646 |archive-date=2012-07-23}}</ref>
<ref name="Microsoft_1995_CONFIG">{{cite web |title=Windows 95 CD-ROM CONFIG.TXT File - Microsoft Windows 95 README for MS-DOS Config.sys Commands |id=KB135481. Q135481 |version=Revision: 1.1 |publisher=[[Microsoft]] |date=2006-11-15 |orig-year=August 1995 |url=http://support.microsoft.com/kb/135481/EN-US |access-date=2011-12-22 |url-status=dead |archive-url=https://archive.today/20130128224809/http://support.microsoft.com/kb/135481/EN-US |archive-date=2013-01-28 |quote=[…] For each hard disk, specifies whether to record the date that files are last accessed. Last access dates are turned off for all drives when your computer is started in safe mode, and are not maintained for floppy disks by default. Syntax: <code>[[ACCDATE (CONFIG.SYS directive)|ACCDATE]]=drive1+{{!}}- [drive2+{{!}}-]…</code> […]}}</ref>
<ref name="Microsoft_1998_CONFIG">{{cite web |title=The Windows 98 Config.txt File - Microsoft Windows 98 README for MS-DOS Config.sys Commands |publisher=[[Microsoft Corporation]] |id=ID 232557 |date=2017-01-07 |orig-year=April 1998 |edition=1 |url=http://support.microsoft.com/?kbid=232557 |access-date=2017-09-10 |url-status=dead |archive-url=https://web.archive.org/web/20180103011840/https://support.microsoft.com/en-us/help/232557/the-windows-98-config-txt-file |archive-date=2018-01-03}}</ref>
<ref name="Childs_1995_OS2">{{cite web |url=http://www.markcrocker.com/rexxtipsntricks/rxtt28.2.0795.html |title=CONFIG.SYS statements used by OS/2 |work=REXX Tips & Tricks, Version 2.80 |author-first=Peter |author-last=Childs |version=0.9b |date=1995 |access-date=2009-01-17 |url-status=dead |archive-url=https://web.archive.org/web/20120220031733/http://www.markcrocker.com/rexxtipsntricks/rxtt28.2.0795.html |archive-date=20 February 2012 }}</ref>
<ref name="Paul_2017_DR">{{cite web |title=The continuing saga of Windows 3.1 in enhanced mode on OmniBook 300 |author-first=Matthias R. |author-last=Paul |orig-year=2017-08-07 |date=2017-08-14 |work=MoHPC - the Museum of HP Calculators |url=http://hpmuseum.org/forum/thread-8774-post-77196.html#pid77196 |access-date=2018-05-01 |url-status=live |archive-url=https://web.archive.org/web/20180501185933/http://hpmuseum.org/forum/thread-8774-post-77196.html |archive-date=2018-05-01 |quote=[…] SYS […] /A Additionally copy [D]CONFIG.SYS and AUTOEXEC.BAT file(s). […] /B or /L Do not modify the Boot Sector in destination (with LOADER). […] /DR[:ext] Use other file extension for system files (BIN) (with LOADER). […]}}</ref>
<ref name="CCI_1997_HELP">{{cite book |title=CCI Multiuser DOS 7.22 GOLD Online Documentation |id=HELP.HLP |date=1997-02-10 |publisher=[[Concurrent Controls, Inc.]] (CCI)}}</ref>
<ref name="CCI_1997_PRINTDOC">{{cite book |title=CCI Multiuser DOS 7.22 GOLD Installation Guide |id=PRINTDOC.HLP |date=1997-02-10 |publisher=[[Concurrent Controls, Inc.]] (CCI)}}</ref>
<ref name="Datalight_2005_ROM-DOS">{{cite web |title=Datalight ROM-DOS User's Guide |date=April 2005 |orig-year=1999 |id=3010-0200-0716 |author1=Datalight, Inc. |author-link1=Datalight, Inc. |author2=GPvNO |publisher=[[Datalight, Inc.]] |url=https://www.datalight.com/assets/files/ROM-DOS_Users_Guide.pdf |access-date=2018-09-16 |url-status=live |archive-url=https://web.archive.org/web/20190421143059/https://www.datalight.com/assets/files/ROM-DOS_Users_Guide.pdf |archive-date=2019-04-21}}</ref>
<ref name="DCP_2016">{{cite web |title=Betriebssystem DCP |author-first1=Rüdiger |author-last1=Kurth |author-first2=Martin |author-last2=Groß |author-first3=Henry |author-last3=Hunger |date=2016-11-29 |orig-year=2007 |language=de |website=www.robotrontechnik.de |url=http://www.robotrontechnik.de/html/software/dcp.htm |access-date=2019-04-28 |url-status=live |archive-url=https://web.archive.org/web/20190403061152/http://www.robotrontechnik.de/html/software/dcp.htm |archive-date=2019-04-03}}</ref>
<ref name="Paul_2004_YESCHAR">{{cite web |title=Re: Random Lockups with DR-DOS 7.03 |date=2004-06-17 |author-first=Matthias R. |author-last=Paul |work=opendos@delorie.com; [[FidoNet]] conference: ALT_DOS |number=1 |url=https://fidonet.ozzmosis.com/echomail.php/alt_dos/7e55a758c10339d0.html |access-date=2019-04-28 |url-status=dead |archive-url=https://archive.today/20190428181923/https://fidonet.ozzmosis.com/echomail.php/alt_dos/7e55a758c10339d0.html |archive-date=28 April 2019 }} [https://archive.today/20190501023752/http://www.delorie.com/opendos/archives/browse.cgi?p=opendos/2004/06/17/07:47:11.1][https://archive.today/20190428182007/http://www.fybertech.com/misc/qwkview/qwkview.pl?conf=3010]</ref>
<ref name="Paul_2004_CHAIN">{{cite web |title=Re: Random Lockups with DR-DOS 7.03 |date=2004-06-17 |number=2 |author-first=Matthias R. |author-last=Paul |work=opendos@delorie.com; [[FidoNet]] conference: ALT_DOS |url=https://fidonet.ozzmosis.com/echomail.php/alt_dos/f2b6d63fc10339d0.html |access-date=2019-04-28 |url-status=dead |archive-url=https://archive.today/20190428181843/https://fidonet.ozzmosis.com/echomail.php/alt_dos/f2b6d63fc10339d0.html |archive-date=28 April 2019 }} [https://archive.today/20190501023518/http://www.delorie.com/opendos/archives/browse.cgi?p=opendos/2004/06/17/07:47:11][https://archive.today/20190428182007/http://www.fybertech.com/misc/qwkview/qwkview.pl?conf=3010]</ref>
<ref name="Paul_2004_COMMAND">{{cite web |title=Re: Random Lockups with DR-DOS 7.03 |date=2004-06-17 |number=3 |author-first=Matthias R. |author-last=Paul |work=opendos@delorie.com; [[FidoNet]] conference: ALT_DOS |url=https://fidonet.ozzmosis.com/echomail.php/alt_dos/e812a919c10339d0.html |access-date=2019-04-28 |url-status=dead |archive-url=https://archive.today/20190428181749/https://fidonet.ozzmosis.com/echomail.php/alt_dos/e812a919c10339d0.html |archive-date=2019-04-28 |quote=[…] all MS-DOS versions prior to Windows 95 […] used a COM style COMMAND.COM file which has a special signature at the start of the file […] queried by the MS-DOS BIOS before it loads the shell, but not by the DR-DOS BIOS […] COMMAND.COM would […] check that it is running on the "correct" DOS version, so if you would load their COMMAND.COM under DR-DOS, you would receive a "Bad version" error message and their COMMAND.COM would exit, so DR-DOS would […] display an error message "Bad or missing command interpreter" (if DR-DOS was trying to load the SHELL= command processor after having finished CONFIG.SYS processing). In this case, you could enter the path to a valid DR-DOS COMMAND.COM (C:\DRDOS\COMMAND.COM) and everything was fine. Now, things have changed since MS-DOS 7.0 […] COMMAND.COM has internally become an EXE style file, so there is no magic […] signature […] to check […] thus no way for DR-DOS to rule out an incompatible COMMAND.COM. Further, their COMMAND.COM no longer does any version checks, but […] does not work under DR-DOS […] just crashes […] the PC DOS COMMAND.COM works fine under DR-DOS […]}} [https://archive.today/20190501023329/http://www.delorie.com/opendos/archives/browse.cgi?p=opendos/2004/06/17/06:23:16][https://archive.today/20190428182007/http://www.fybertech.com/misc/qwkview/qwkview.pl?conf=3010]</ref>
<ref name="Paul_2000_CONFIG">{{cite web |title=Optimizing CONFIG.SYS… |date=2000-11-22 |author-first=Matthias R. |author-last=Paul |work=opendos@delorie.com |url=http://www.delorie.com/opendos/archives/browse.cgi?p=opendos/2000/11/22/11:09:09 |access-date=2019-05-06 |url-status=live |archive-url=https://archive.today/20190506023131/http://www.delorie.com/opendos/archives/browse.cgi?p=opendos/2000/11/22/11:09:09 |archive-date=2019-05-06}}</ref>
<ref name="RxDOS724">{{cite web |author=ecm |title=RxDOS 7.24 release |date=2018-10-08 |website=bttr-software.de |series=DOS ain't dead |url=http://www.bttr-software.de/forum/board_entry.php?id=15627 |access-date=2020-01-27 |url-status=live |archive-url=https://web.archive.org/web/20181215010804/http://www.bttr-software.de/forum/board_entry.php?id=15627 |archive-date=2018-12-15}}</ref>
<ref name="Paul_2002_CTMOUSE">{{cite web |title=Re: [fd-dev] ANNOUNCE: CuteMouse 2.0 alpha 1 |author-first=Matthias R. |author-last=Paul |work=freedos-dev |date=2002-04-06 |url=https://marc.info/?l=freedos-dev&m=101807226917577 |access-date=2020-02-07 |url-status=live |archive-url=https://web.archive.org/web/20200207130948/https://marc.info/?l=freedos-dev&m=101807226917577&w=2 |archive-date=2020-02-07 |quote=[…] [[DR-DOS 7.02]]+ has a [D]CONFIG.SYS directive to override the [[serial port]]s detected during System BIOS [[Power On Self Test|POST]], so tools like [[DEBUG (DOS command)|DEBUG]] […] are no longer required to update or change the port settings in segment 40h. […] insert a line to [D]CONFIG.SYS to make the port available to the [[System BIOS]], DOS, and most drivers and applications: […] COM4=260,1 ; set [[I/O address]] for [[COM4]] to 260h, timeout 1 […] Since old machines and DOS versions did not know about [[COM3]] and COM4 at all, good software will try to use the data stored in segment 0040h […] Optionally hide the chosen mouse COM port from the system configuration to avoid any clobbering by old [[BASIC]] programs. […]}}</ref>
<ref name="Ernst_1987_DRIVER">{{cite magazine |title=Damit die Scheibe spurt - 720 KB-Disketten mit MF-Drives im AT; Atari ST-Disketten unter DOS ab Version 3.2 in PCs, ATs oder Modell 30 |language=de |series=Programm |author-first1=Martin |author-last1=Ernst |author-first2=Detlef |author-last2=Grell |editor-first=Detlef |editor-last=Grell |date=November 1987 |magazine=[[c't - magazin für computertechnik]] |publisher=[[Verlag Heinz Heise GmbH & Co. KG]] |volume=1987 |issue=11 |issn=0724-8679 |pages=216-218, 220, 222, 224, 226, 228 [226<!-- relevant page -->]}}</ref>
<ref name="ecom_2001">{{cite web |url=http://www.ecomstation.com/docs/release1.0/ecs-ga-pdf-a5.pdf |date=2001 |access-date=2020-10-08 |website=ecomstation.com |title=eComStation 1.0 Manual}}</ref>
<ref name="ArcaOS_2020">{{cite web |url=https://www.arcanoae.com/wiki/arcaos/updating-from-a-prior-release/troubleshooting-the-arcaos-update-procedure/ |title=Troubleshooting the ArcaOS update procedure |access-date=2020-10-08 |website=arcanoae.com}}</ref>
<ref name="Schneider_1994">{{cite journal |title=Das Ende von DOS ist nur noch eine Frage der Zeit |language=de |trans-title=The end of DOS is only a question of time |author-first=Stefanie |author-last=Schneider |journal=[[Computerwoche]] |publisher=[[IDG Business Media GmbH]] |location=Munich, Germany |date=1994-06-17 |url=https://www.computerwoche.de/a/das-ende-von-dos-ist-nur-noch-eine-frage-der-zeit,1121952 |access-date=2022-01-02 |url-status=live |archive-url=https://web.archive.org/web/20220102151737/https://www.computerwoche.de/a/das-ende-von-dos-ist-nur-noch-eine-frage-der-zeit,1121952 |archive-date=2022-01-02 |quote=[…] So handelt es sich bei dem fuer Ende 1994, Anfang 1995 erwarteten [[MS-DOS 7.0]] offenkundig um eine der grafischen Benutzeroberflaeche entledigte Version von [[Windows 4.0]], die auch den Codenamen "[[Microsoft Chicago|Chicago]]" traegt. Dieses neue DOS soll der CW-Schwesterpublikation "PC-Welt" zufolge durch die neuen Parameter "standard" und "enhanced" in der Systemdatei Io.sys die leidigen Speicherbarrieren ueberwinden. […]}} (NB. The undocumented settings <code>STANDARD</code> and <code>ENHANCED</code> are optional parameters of the CONFIG.SYS directive <kbd>[[DOS (CONFIG.SYS directive)|DOS]]</kbd>.)</ref>
}}

== External links ==
* {{cite web |title=AUTOEXEC.BAT and CONFIG.SYS information |date=2017-12-29 |publisher=Computer Hope |url=http://www.computerhope.com/ac.htm |access-date=2018-05-12 |url-status=live |archive-url=https://web.archive.org/web/20180512093519/https://www.computerhope.com/ac.htm |archive-date=2018-05-12}}
* {{cite web |title=Description of Windows 98 / MS-DOS 7.10 CONFIG.SYS directives |url=http://support.microsoft.com/?kbid=232557 |url-status=dead |archive-url=https://web.archive.org/web/20060212042929/http://support.microsoft.com/?kbid=232557 |archive-date=2006-02-12}}
* {{cite web |title=CONFIG.SYS Command Reference |date=1998 |publisher=[[Caldera (company)|Caldera]] |url=http://www.drdos.net/documentation/usergeng/09ugch9.htm#807 |access-date=2018-05-12 |url-status=dead |archive-url=https://web.archive.org/web/20180512093720/http://www.drdos.net/documentation/usergeng/09ugch9.htm |archive-date=2018-05-12}} (Description of DR-DOS 7 CONFIG.SYS directives (incomplete))
* {{cite web |title=Description of FreeDOS CONFIG.SYS directives |url=http://help.fdos.org/en/hhstndrd/cnfigsys/index.htm |access-date=2018-05-12 |url-status=live |archive-url=https://web.archive.org/web/20180512093840/http://help.fdos.org/en/hhstndrd/cnfigsys/index.htm |archive-date=2018-05-12}}
* {{cite web |title=PTS-DOS 2000 Pro User Manual including a description of PTS-DOS CONFIG.SYS directives (incomplete) |url=http://download.paragon-software.com/doc/manual_dos_eng.pdf |access-date=2018-05-12 |url-status=live |archive-url=https://web.archive.org/web/20180512094512/http://download.paragon-software.com/doc/manual_dos_eng.pdf |archive-date=2018-05-12}}
* {{cite web |title=Inoffizielle deutschsprachige PTS-DOS-FAQ (PTS/FAQD), unofficial PTS-DOS FAQ as of 2004-04-25, including more CONFIG.SYS directives |date=25 April 2004 |language=de |url=http://www.almnet.de/ptsdos/ptsfaqd.html |access-date=2018-05-12 |url-status=live |archive-url=https://web.archive.org/web/20180512093757/https://almnet.de/ptsdos/ptsfaqd.html |archive-date=2018-05-12}}

{{DOS system files}}

{{DEFAULTSORT:Config.Sys}}
[[Category:DOS configuration files]]
[[Category:OS/2 files]]
[[Category:Configuration files]]<!-- left in here, because also an OS/2 configuration files -->