CONFIG.SYS commands

October 2016

The Config.sys is the main configuration file used by OS/2, MS-DOS and other operating systems and contains commands and instructions for the working of the computer system. 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 comprises mostly of name and value pairs that include commands such as DEVICEHIGH, install, lastdrive, set, shell etc. The OS/2 depends on the config.sys file for configuration before the graphics of the system start.

The CONFIG.SYS commands load programs into memory and manage the operation of your equipment. For the most part, they are used only in the CONFIG.SYS file, with the exception of break commands, and rem set, you can also include 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.

or rem;
  • 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 = fr,, keyboard.sys 

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

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