CONFIG.SYS - CONFIG.SYS Directives

CONFIG.SYS Directives

: (DR DOS 5.0 and higher only)

Defines labels in CONFIG.SYS as jump targets for CHAIN, DRSWITCH, GOTO, GOSUB and SWITCH directives.

; (DOS 6.0 and DR DOS 6.0 and higher)

Similar to REM, but can be used also for in-line comments (following other CONFIG.SYS directives). See COMMENT. (Under MS-DOS/PC DOS the inline-comment is not ignored if put in double-quotes.)

? (DR DOS 3.41 and higher and FreeDOS only)

Displays a Yes/No query and (since DR DOS 5.0) optional message to ask the user for confirmation to execute the following CONFIG.SYS directives. (FreeDOS does not support optional messages, but optional conditions in conjunction with boot menus defined with MENU and MENUDEFAULT.) (DOS 6.0 and higher supports a similar feature by adding a ? after the corresponding CONFIG.SYS directive, f.e. DEVICE? or DEVICE?= instead of ?DEVICE. This variant is also supported by DR DOS.)

! (FreeDOS only)

Unconditionally execute the following CONFIG.SYS directive.

ACCDATE (MS-DOS 7.0 and higher only, ignored under DR-DOS 7.02 and higher)

Configures which drives should store file access date stamps in FAT file systems or not.

AUX (DR-DOS 7.02 and higher only)

Changes internal default serial device driver (COM1: to COM4:) for AUX: device.

AVAILDEV (DOS 2.0-2.1 and DR-DOS 7.02 and higher only)

Disables the availability of character devices outside of phantom \DEV directory.

BEEP (DR-DOS 7.02 and higher only)

Emits a short beep, even if audible notifications are disabled via SWITCHES=/Q.

BREAK (DOS 2.0 and DR DOS 3.31 and higher)

Sets or clears extended Ctrl+C checking.

BUFFERS (DOS 2.0 and DR DOS 3.31 and higher)

Specifies the number of disk buffers to allocate.

BUFFERSHIGH (MS-DOS 7.0 and DR-DOS 7.02 and higher and FreeDOS only)

Same as BUFFERS, but explicitly loads buffers into HMA or UMB (like HIBUFFERS under DR DOS 6.0 and higher).

CAPSLOCK (DR-DOS 7.02 and higher only)

Specifies whether the keyboard ⇪ Caps Lock status is turned on or off.

CHAIN (DR DOS 5.0 and higher only)

Continues CONFIG.SYS processing in new file and (since DR-DOS 7.02) at optional label.

CLS (DR DOS 6.0 and higher only)

Clears screen.

COM1 (DR-DOS 7.02 and higher only)

Defines count and logical order and configures I/O address and timeout for COM1: device.

COM2 (DR-DOS 7.02 and higher only)

Defines count and logical order and configures I/O address and timeout for COM2: device.

COM3 (DR-DOS 7.02 and higher only)

Defines count and logical order and configures I/O address and timeout for COM3: device.

COM4 (DR-DOS 7.02 and higher only)

Defines count and logical order and configures I/O address and timeout for COM4: device.

COMMENT (DOS 4.0 and higher and RxDOS, ignored under DR-DOS 7.02 and higher)

Redefines the lead-in character(s) for CONFIG.SYS inline-comments, or causes the following line to be ignored.

COUNTRY (DOS 3.0 and DOS Plus 2.1 with FIDDLOAD and DR DOS 3.31 and higher)

Enables and configures international support.

CPOS (DR DOS 6.0 and higher only)

Sets display cursor to specified position for configuation menus.

CPSW (MS-DOS 4.00-4.01 only, ignored under DR-DOS 7.02 and higher)

For codepage switching support.

CPU386 (DR-DOS 7.02 and higher and PTS-DOS only)

Conditional execution on 386 and higher CPUs only, f.e. CPU386 DEVICE=C:\DOS\EMM386.EXE or CPU386 GOTO label386

DEBLOCK (DR DOS 6.0 (1993 update) and higher only)

Specifies the memory segment address up to which multi-sector disk data deblocking is allowed.

DEBUG (DR DOS 3.31 - 6.0 and 7.02 and higher only)

Enables internal debugger support.

DEVICE (DOS 2.0 and DOS Plus 2.1 with FIDDLOAD and DR DOS 3.31 and higher)

Loads a device driver into memory.

DEVICEHIGH (DOS 5.0 and DR DOS 6.0 and higher)

Loads a device driver into upper memory. (Same as HIDEVICE in DR DOS 5.0.)

DISKCACHE (OS/2 only, ignored under DR-DOS 7.02 and higher)

Internal use.

DOS (DOS 5.0 and DR DOS 6.0 and higher)

Specifies whether to load DOS into the high memory area and/or use upper memory. (Similar to HIDOS=ON under DR DOS 5.0.)

DOSDATA (PC DOS 7.0 and higher and FreeDOS only)

Specifies whether to load DOS tables (BUFFERS, FCBS, FILES, LASTDRIVE, STACKS) into upper memory.

DRIVPARM (DOS 3.2 and higher)

Define parameters for unrecognized drives.

DRSWITCH (DR DOS 7.02 and higher only)

See SWITCH.

ECHO (DR DOS 5.0 and higher and FreeDOS only)

Displays a message on screen.

EECHO (FreeDOS only)

Displays a message including ANSI Escape sequences.

ERROR (DR DOS 6.0 and higher only)

Specifies an error / return code to be assumed in the following.

EXIT (DR DOS 6.0 and higher only)

Finishes CONFIG.SYS processing before the end of the file has been reached (except for SWITCHES and SHELL directive processing under some conditions).

FASTOPEN (DR DOS 3.31 and higher only)

Specified the size of the hash table for fast file open operations. Works considerably different than the external MS-DOS/PC DOS FASTOPEN driver.

FCBS (DOS 3.0 and DR DOS 3.31 and higher)

Specifies the number of cached FCBs that can be opened at once. (Under DR-DOS, FCBS and FILES dynamically share the same internal buffer.)

FCBSHIGH (MS-DOS 7.0 and DR-DOS 7.02 and higher only)

Same as FCBS, but explicitly loads FCBs into upper memory.

FILES (DOS 2.0 and DR DOS 3.31 and higher)

Specifies the number of files that can be opened at once.

FILESHIGH (MS-DOS 7.0 and DR-DOS 7.02 and higher and FreeDOS only)

Same as FILES, but explicitly loads file handles into upper memory.

GETKEY (DR DOS 6.0 and higher only)

Waits for key (or timeout) and sets error level to its ASCII code (or 1024 on timeout).

GOTO (DR DOS 5.0 and higher only)

Continues CONFIG.SYS processing at specified label.

GOSUB (DR DOS 6.0 and higher only)

Continues nested CONFIG.SYS processing at specified label, with RETURN returning to old location.

HIBUFFERS (DR DOS 6.0 and higher only)

See BUFFERSHIGH or DOS=HIGH,UMB or DOSDATA.

HIDEVICE (DR DOS 5.0 and higher only)

See DEVICEHIGH.

HIDOS (DR DOS 5.0 and higher only)

See DOS=HIGH,UMB.

HIFCBS (DR DOS 7.02 and higher only)

See FCBSHIGH or DOSDATA.

HIFILES (DR DOS 7.02 and higher only)

See FILESHIGH or DOSDATA.

HIINSTALL (DR DOS 5.0 and higher only)

See INSTALLHIGH.

HILASTDRIVE (DR-DOS 7.02 and higher only)

See LASTDRIVEHIGH or DOS=UMB or DOSDATA.

HISHELL (DR-DOS 7.02 and higher only)

See SHELLHIGH.

HISTACKS (DR-DOS 7.02 and higher only)

See STACKSHIGH or DOSDATA.

HISTORY (DR DOS 3.41 and higher only)

Enables and configures console and command line history buffer and extended pattern search functionality.

IFS (MS-DOS 4.00-4.01 only, ignored under DR-DOS 7.02 and higher)

For installable file system support.

INCLUDE (DOS 6.0 and higher, not DR-DOS, not FreeDOS)

Include directives from another menu block. (Can be emulated using GOSUB and RETURN under DR-DOS.)

INSERT (DR-DOS 7.02 and higher only)

Specifies whether the keyboard Insert mode status is turned on or off.

INSTALL (DOS 4.0 and DR DOS 3.41 and higher)

Installs a TSR program into memory.

INSTALLHIGH (DOS 6.0 and DR DOS 6.0 and higher)

Installs a TSR program into upper memory. (Same as HIINSTALL in DR DOS 5.0.)

LASTDRIVE (DOS 3.0 and DOS Plus 2.1 with FIDDLOAD and DR DOS 3.31 and higher)

Specifies the maximum of drives that can be accessed.

LASTDRIVEHIGH (MS-DOS 7.0 and DR-DOS 7.02 and higher and FreeDOS only)

Same as LASTDRIVE, but explicitly loads the Current Directory Structure (CDS) into upper memory.

LOGO (MS-DOS 7.0 and higher only, ignored under DR-DOS 7.02 and higher)

Configures boot logo support.

LPT1 (DR-DOS 7.02 and higher only)

Defines count and logical order and configures I/O address and timeout for LPT1: device.

LPT2 (DR-DOS 7.02 and higher only)

Defines count and logical order and configures I/O address and timeout for LPT2: device.

LPT3 (DR-DOS 7.02 and higher only)

Defines count and logical order and configures I/O address and timeout for LPT3: device.

LPT4 (some versions of DR-DOS 7.02 and higher only)

Enables, defines count and logical order and configures I/O address and timeout for LPT4: device.

MENU (FreeDOS only)

Defines menu options.

MENUCOLOR (DOS 6.0 and higher, not DR DOS, not FreeDOS)

Specifies menu colors. (Can be emulated using ECHO under DR-DOS.)

MENUDEFAULT (DOS 6.0 and higher and FreeDOS, not DR DOS)

Specifies the default menu block. (Can be emulated using TIMEOUT and SWITCH under DR-DOS.)

MENUITEM (DOS 6.0 and higher, not DR DOS, not FreeDOS)

Specifies a menu block. (Can be emulated using ECHO and SWITCH under DR-DOS.)

MULTITRACK (DOS 4.0 and DR-DOS 7.02 and higher)

Specifies whether multitrack disk operations are used or not.

NOCHAR (DR-DOS 7.02 and higher only)

Specifies the default No (N) character in Yes/No/Resume questions.

NUMLOCK (DOS 6.0 and Novell DOS 7 and higher)

Specifies whether the keyboard Num Lock status is turned on or off.

ONERROR (DR DOS 6.0 and higher only)

Conditional execution depending on last return code/error status only, f.e. ONERROR > 0 GOTO failload or ONERROR > 10 ONERROR <> 17 ONERROR <= 30 ECHO Error 11-16 or 18-30 occurred.

PRN (DR-DOS 7.02 and higher only)

Changes internal default printer device driver (LPT1 to LPT3, or even LPT4) for PRN device.

REM (DOS 4.0 and DR DOS 3.31 and higher)

Allows comments in CONFIG.SYS.

RESUMECHAR (DR-DOS 7.02 and higher only)

Specifies the default Resume (R) character in Yes/No/Resume queries.

RETURN (DR DOS 6.0 and higher only)

Returns nested CONFIG.SYS processing at previous location of GOSUB or SWITCH directive. An optional return code can be given, otherwise 0 is assumed.

RMSIZE (OS/2 only, ignored under DR-DOS 7.02 and higher)

Defines the real mode memory size.

SCREEN (FreeDOS only)

Specifies the video mode to be used.

SCROLLOCK (DR-DOS 7.02 and higher only)

Specifies whether the keyboard Scroll Lock status is turned on or off.

SET (DOS 6.0 and DR DOS 6.0 and higher)

Sets environment variables.

SHELL (DOS 2.0 and DR DOS 3.31 and higher)

Loads the command interpreter shell.

SHELLHIGH (DR-DOS 7.02 and higher and FreeDOS only)

Same as SHELL, but supports an additional SIZE parameter to define the size of the pre-allocation for COMMAND.COM to relocate its resident portion into the HMA (with /MH). Can be useful to avoid HMA fragmentation in conjunction with third-party shells which cannot load into the HMA.

STACK (ignored under DR DOS 3.31-5.0 and 7.02 and higher only)

Compatibility dummy - DR DOS 3.31 - 6.0 were mostly reentrant and had a different stacks layout.

STACKS (DOS 3.2 and Novell DOS 7 and higher, ignored under DR DOS 6.0)

Specifies the number of stacks for hardware interrupts.

STACKSHIGH (MS-DOS 7.0 and DR-DOS 7.02 and higher and FreeDOS only)

Same as STACKS, but explicitly loads buffers into upper memory.

STRING (MS-DOS 3.0 only, ignored under DR-DOS 7.02 and higher)

Internal use.

SUBMENU (DOS 6.0 and higher, not DR DOS, not FreeDOS)

Specifies a submenu block. (Can be emulated using CLS, ECHO and SWITCH under DR-DOS.)

SWITCH (DR DOS 6.0 and higher only)

Conditionally continues nested CONFIG.SYS processing at one of the specified labels depending on keys pressed, with RETURN returning to old location.

SWITCHAR (DOS 2.0-2.1, DOS Plus 2.1 with FIDDLOAD, DR-DOS 7.02 and higher, FreeDOS and RxDOS only)

Defines the default SwitChar used by the system (either '/' or '-').

SWITCHES (DOS 4.0 and Novell DOS 7 and higher)

Specifies special options.

TIMEOUT (DR DOS 6.0 and higher only)

Specifies the timeouts in CONFIG.SYS single-stepping and with SWITCH, GETKEY and ?, and the default answers for Yes/No queries and SWITCH selections.

TRACE (DR-DOS 7.02 and higher and PTS-DOS only)

Globally or locally enables or disables CONFIG.SYS (and AUTOEXEC.BAT) single-stepping execution.

VERIFY (DR-DOS 7.02 and higher only)

Enables or disables disk write verification.

VERSION (FreeDOS only)

Specifies the DOS version to be reported to programs.

YEAR2000 (DR-DOS 7.02 and higher only)

Configures the built-in Year 2000 support.

YESCHAR (PalmDOS 1.0, DR DOS 6.0 updates and Novell DOS 7 and higher only)

Specifies the default Yes (Y) character in Yes/No/Resume queries.