Key System Components

Windows Subsystem
Windows의 주 Subsystem은 Windows 이기 때문에 POSIX, OS/2의 경우사실상 Windows의 Subsystem을 호출하는 경우가 많다.

Environment subsystem process (Csrss.exe)

. Console (text) windows
. Creating and deleting processes and threads
. Portions of the support for 16-bit virtual DOS machine (VDM) processes
. Other miscellaneous functions, such as GetTempFile, DefineDosDevice, ExitWindowsEx, and several natural language support functions

The kernel-mode device driver (Win32k.sys)

. The window manager, which controls window displays; manages screen output; collects input from keyboard, mouse, and other devices; and passes user messages to applications.
. The Graphics Device Interface (GDI), which is a library of functions for graphics output devices. It includes functions for line, text, and figure drawing and for graphics manipulation.

Subsystem DLLs (such as Kernel32.dll, Advapi32.dll, User32.dll, and Gdi32.dll) translate documented Windows API functions into the appropriate and mostly undocumented kernel-mode system service calls to Ntoskrnl.exe and Win32k.sys.

Graphics device drivers are hardware-dependent graphics display drivers, printer drivers, and video miniport drivers.