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CONFIG.SYS commands

The Config.sys is the main configuration file used by OS/2, MS-DOS and other operating systems. Config.sys commands loads programs into the memory and sets ups the memory management of the system. The command shell is executed after the config.sys has been processed. After the command shell is loaded, the autoexec.bat file is processed.


The CONFIG.SYS commands load programs into memory and manage the operation of your equipment. They are used only in the CONFIG.SYS file, with the exception of break commands. You can also include them in the AUTOEXEC.BAT file or type in the MS-DOS.

Typically, the CONFIG.SYS file contains only some of these commands.


The following table describes all the commands available in this file:


  • Specifies whether MS-DOS must check the key combination CTRL + C or CTRL + PAUSE. For more information, type help to break the MS-DOS.


  • Specifies the amount of memory reserved for data transfer between memory and disks. For more information, type help buffers at the MS-DOS.


  • Defines the conventions to use. For more information, type help country at the MS-DOS.


  • Loads an installable device manager. A device manager is a program that manages a physical element, such as the mouse or the memory card. For more information, device type help at the MS-DOS.


  • Loads an installable device manager in the upper memory area. For more information, type help DEVICEHIGH at the MS-DOS.


  • Specifies whether MS-DOS must use the high memory area (HMA) and allows access to the upper memory area. For more information, type help back to the MS-DOS.


  • Defines the characteristics of a disk drive. For more information, type help drivparm at the MS-DOS.


  • Specifies the number of files that MS-DOS can open simultaneously. For more information, type help files in MS-DOS.


  • Loads a program resident in memory. For more information, type help install at the MS-DOS.


  • Sets the number of drive letters recognized by MS-DOS. For more information, type help lastdrive at the MS-DOS.


  • Specifies whether the function of locking the keypad is initially turned on or not.


  • Introduces a comment line and not a command. Can also be used to disable a command. For more information, type help to replace the MS-DOS.


  • Sets the value of environment variables such as TEMP or PROMPT. For more information, type help set the MS-DOS.


  • Configure COMMAND.COM or indicates that another command interpreter must be used. For more information, type help shell or help command to MS-DOS.


  • Sets the amount of memory to reserve for the treatment of physical interruptions. For more information, type help stacks at the MS-DOS.


  • Specifies the use of the functions of a conventional keyboard, even if you use an extended keyboard. For more information, type help switches to the MS-DOS.


The CONFIG.SYS file can also contain commands including: menucolor, menudefault and menuitem submenu.

Example command lines of a CONFIG.SYS file:

menuitem = CD, Start with support for CD-ROM
menuitem = NOCD, Start without support CD-ROM
menuitem = HELP, View the Help file
menudefault = CD, 30
menucolor = 7.0
himem.sys device = / testmem we
oakcdrom.sys device = / D: mscd001
device = btdosm.sys
device = flashpt.sys
btcdrom.sys device = / D: mscd001
device = aspi2dos.sys
device = aspi8dos.sys
device = aspi4dos.sys
device = aspi8u2.sys
aspicd.sys device = / D: mscd001
himem.sys device = / testmem: off
himem.sys device = / testmem: off
files = 10
buffers = 10
dos = high, umb
stacks = 9.256
DEVICEHIGH = ramdrive.sys / E 2048
lastdrive z =
device = display.sys con = (ega,, 1)
country = 033.850, country.sys
install = MODE.COM con cp prepare = ((850) EGA.CPI)
install = MODE.COM con cp select = 850
install = Keyb.com fr,, keyboard.sys

These command lines are for the boot disk with support for CD-ROM.

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