Environmental Subsystems
	• User-mode processes layered over the native XP executive services – Enable XP to run programs developed for other operating system • XP uses the Win32 subsystem as the main operating environment – Win32 is used to start all processes – Also provides all the keyboard, mouse and graphical display capabilities • MS-DOS environment is provided by Win32 application called the virtual DOS machine (VDM), – A user-mode process that is paged and dispatched like any other XP thread