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(operating system)
A text file containing special system configuration commands. It is found in the root directory on an MS-DOS computer, typically on drive C (the hard disk). It is read by MS-DOS at boot time, after the setup has been read from CMOS RAM and before running AUTOEXEC.BAT. It can be modified by the user.

Some example commands which CONFIG.SYS might contain are:

DEVICE=C:\DOS\HIMEM.SYS /testmem:off

Load the extended memory manager.


Load the expanded memory manager.


Specify memory for disk buffers.


Set the number of files that can be open at once.


DOS is located in UppeMemoryBlock.


Disk drives are A: to Z:.


Set the number of file control blocks.


Report the DOS version to older programs.


DOS should maintain a link to UMB.


Set the country code for some programs.


Set dynamic stacks for hardware control.


Set the location of the command interpreter.


(CONFIGure SYStem) A text file that contained commands to load drivers and establish settings in a DOS PC. Along with AUTOEXEC.BAT, it resided in the root folder. CONFIG.SYS was included in Windows versions for DOS compatibility and was replaced with CONFIG.NT in 32-bit versions of Windows starting with Windows NT. Users could easily make changes, and installation programs sometimes modified CONFIG.SYS for their own purposes.

The following CONFIG.SYS example primarily loads memory managers that were essential to squeeze programs into every byte of what little RAM there was at the time. See AUTOEXEC.BAT, UMA, HIMEM.SYS and EMM386.EXE.
 Driverdevice=c:\dos\himem.sys       RAM > 1MB
 device=c:\dos\emm386.exe ram  EMS memory
 device=c:\dos\ansi.sys        screen/KB
 device=c:\mouse\mouse.sys     mouse
References in periodicals archive ?
Device drivers are loaded into memory by the CONFIG.
Because these drivers are built into DOS, they are automatically loaded with DOS; thus, we do not need th use CONFIG.
The next important step is to make sure to have a DOS=HIGH,UMB statement in CONFIG.
For instance, SMARTDRV does not need to be loaded as a device in our CONFIG.
Stacker does all this magic by inserting a couple of lines into your CONFIG.
Once you have DR DOS running, changes can be made to CONFIG.
In order to achieve this, you must put a line in your CONFIG.
Before you begin making any changes to either CONFIG.
EDLIN was included in order to provide some recognition feature if telephone directions were required for the editing of CONFIG.
We called other librarians and discussed installation problems, particularly the CONFIG.