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. Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... OS/2 is an operating system created by Microsoft and IBM and later developed by IBM exclusively. ... An operating system (OS) is an essential software program that manages the hardware and software resources of a computer. ... A command line interpreter is a computer program which reads lines of text that the user types and interprets them in the context of a given operating system or programming language. ... COMMAND.COM is the name for the default operating system shell (or command line interpreter) for DOS and 16/32bits versions of Windows (95/98/98 SE/Me). ... AUTOEXEC.BAT is the name of a system file found on the MS-DOS operating system. ...

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. Terminate and Stay Resident (TSR) computer programs were the only way to achieve a primitive sort of multitasking (usually just task-switching) using the DOS operating system. ... Windows XP loading drivers during a Safe Mode bootup A device driver, or a software driver is a specific type of computer software, typically developed to allow interaction with hardware devices. ...

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. In computer file systems, the root directory is the first or top-most directory in a hierarchy. ... It has been suggested that FreeDOS-32 be merged into this article or section. ... DR-DOS is a DOS-family-compatible operating system for IBM PC-compatible personal computers, originally developed by Gary Kildalls Digital Research and derived from CP/M-86. ...

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, instead using startup.cmd. As of 2006, Microsoft Windows is the worlds most common operating system for use on personal computers. ... OS/2 is an operating system created by Microsoft and IBM and later developed by IBM exclusively. ...

In the OS/2 subsystem of Windows NT, what appeared as CONFIG.SYS to OS/2 programs was actually stored in the registry. OS/2 is an operating system created by Microsoft and IBM and later developed by IBM exclusively. ... Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... OS/2 is an operating system created by Microsoft and IBM and later developed by IBM exclusively. ...

Example CONFIG.SYS file for DOS

 device = c:doshimem.sys device = c:dosemm386.exe umb dos = high,umb devicehigh = c:windowsmouse.sys devicehigh = c:dossetver.exe devicehigh = c:dossmartdrv.exe country = 044,437,c:doscountry.sys shell = c:doscommand.com c:dos /e:512 /p