Backups of the Windows 9x versions are made as .W40 files. Windows 9x also installs MSDOS.SYS, a configuration file, which will not boot Windows 95/98 if parameterBOOTGUI=0 is loaded, and instead a DOS prompt will appear on the screen (Windows can still be loaded by calling the WIN command (file WIN.COM). This file contains some switches that designate how the system will boot, one of which controls whether or not the system automatically goes into Windows. This "BootGUI" option must be set to "0" in order to boot to a DOS prompt. By doing this, the system's operation essentially becomes that of a DOS/Windows pairing like with earlier Windows versions. Windows can be started as desired by typing WIN at the DOS prompt. When installing Caldera DR-DOS 7.02 and higher, the Windows version retains the name AUTOEXEC.BAT, while the file used by the DR-DOS COMMAND.COM is named AUTODOS7.BAT, referred to by the startup parameter /P:filename.ext in the SHELL directive. It also differentiates the CONFIG.SYS file by using the name DCONFIG.SYS. OS/2 The equivalent to AUTOEXEC.BAT under OS/2 is the OS/2 STARTUP.CMD file, however, genuine DOS sessions booted under OS/2 continue to use AUTOEXEC.BAT. Windows NT On Windows NT and its derivatives, Windows 2000, Windows Server 2003 and Windows XP, the equivalent file is called AUTOEXEC.NT and is located in the %SystemRoot%\system32 directory. The file is not used during the operating system boot process; it is executed when the MS-DOS environment is started, which occurs when a DOS application is loaded. The AUTOEXEC.BAT file may often be found on Windows NT in the root directory of the boot drive. Windows only considers the SET and PATH statements which it contains, in order to define environment variables global to all users. Setting environment variables through this file may be interesting if for example MS-DOS is also booted from this drive (this requires that the drive be FAT-formatted) or to keep the variables across a reinstall. This is an exotic usage today so the file usually remains empty. The Tweak UI applet from the Microsoft PowerToys collection allows to control this feature (Parse AUTOEXEC.BAT at logon). See also COMMAND.COM IBMBIO.COM / IO.SYS IBMDOS.COM / MSDOS.SYS SHELL (CONFIG.SYS directive) CONFIG.SYS AUTORUN.INF References DOS files Configuration files MSX-DOS