CONFIG.SYS

From Free net encyclopedia

CONFIG.SYS is the primary configuration file for the MS-DOS and OS/2 operating systems. It is a special file that contains setup or configuration instructions for the computer system. The commands in this file configure DOS for use with devices and applications in the system. The commands also set up the memory managers in the system. After processing the CONFIG.SYS file, DOS proceeds to load and execute the command shell specified in the shell= line of CONFIG.SYS, or COMMAND.COM if there is no such line. The command shell in turn is responsible for processing the AUTOEXEC.BAT file.

The system can still boot if these files are missing or corrupted. However, these two files are essential for the complete bootup process to occur with the DOS operating system. They contain information that is used to change the operating system for personal use. They also contain the requirements of different software application packages. A DOS system would require troubleshooting if either of these files became damaged or corrupted.

CONFIG.SYS is composed mostly of name=value statements which look like variable assignments. In fact these will either define some tunable parameters often resulting in reservation of memory, or load files, mostly TSRs and device drivers, into memory.

In DOS, CONFIG.SYS is located in the root directory of the drive from which DOS was booted. In some versions of DOS it may have an alternate filename, e.g. FDCONFIG.SYS in FreeDOS, or DCONFIG.SYS in some versions of DR-DOS.

Both CONFIG.SYS and AUTOEXEC.BAT can still be found included in the system files of the later Microsoft Windows operating systems. Usually these files are empty files, with no content. OS/2 did not use the autoexec.bat file.

In the OS/2 subsystem of Windows NT, what appeared as CONFIG.SYS to OS/2 programs was actually stored in the registry.

Example CONFIG.SYS file for DOS

device = c:\dos\himem.sys
device = c:\dos\emm386.exe umb
dos = high,umb
devicehigh = c:\windows\mouse.sys
devicehigh = c:\dos\setver.exe
devicehigh = c:\dos\smartdrv.exe
country = 044,437,c:\dos\country.sys 
shell = c:\dos\command.com c:\dos /e:512 /ppl:CONFIG.SYS