Editing CONFIG.SYS (section)

=== 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.