System Startup Files

This section describes the following files involved in Windows 95 system startup:

IO.SYS, which is the real-mode operating system that replaces the MS-DOS version; VMM32 and Windows 95 device drivers take control from IO.SYS

MSDOS.SYS, which contains special information for Windows 95 and is also created for compatibility with applications that require this file to be present before they can be installed
CONFIG.SYS and AUTOEXEC.BAT
SYSTEM.INI and WIN.INI
BOOTLOG.TXT, the log file that describes the system startup processes

The following table summarizes how Setup renames the system files for the previous operating system when Windows 95 is installed. (The Windows 95 files are renamed with .W40 filename extensions when you start the computer with the other operating system.)

Original MS-DOS filename	Renamed file under Windows 95
autoexec.bat	autoexec.dos
command.com	command.dos
config.sys	config.dos
io.sys (or ibmbio.com)	io.dos
mode.com	mode_dos.com
msdos.sys (or ibmdos.com)	msdos.dos