★ “长 OS Architecture ￥斗 ★★ o Environment subsystemprocesses Manage dient processesin theirword Impose semantics such as processmodel, security o Windows2000 shippedwith three environment subsystems: Win32, POSIX, and oS/2 XP has only Windows subsystem Win32 only one that matters DoS, Win3. 1 emulated by a Win32 progam Enhanced posX subsystemavailable(Interix)6 OS Architecture  Environment subsystem processes – Manage client processes in their world – Impose semantics such as process model, security  Windows 2000 shipped with three environment subsystems: Win32, POSIX, and OS/2 – XP has only Windows subsystem – Win32 only one that matters – DOS, Win 3.1 emulated by a Win32 program – Enhanced POSIX subsystem available (Interix)