Composition of win 2 k OS user mode Environment

The kernel mode component does not implement the user interface. What we see is the system expansion component called the subsystem. Subsystems can be divided into two categories based on their work content: the overall subsystem and the Environment Subsystem.
1. Overall Subsystem
The overall subsystem executes some necessary system functions, such as loading, managing, and uninstalling services and drivers, and managing system security together with the account manager and logon process.
2. Environment Subsystem
The Environment subsystem provides programming interfaces and execution environments for applications. Microsotf defines several application programming interfaces (APIS, application program interfaces). User Mode Code regards them as the abstraction of operating system services. These APIs form different environment subsystems where application code resides. Currently, the Environment subsystems listed below are included in win 2 k OS.
(1) The Win32 subsystem is a Windows 2 k OS Local Mode API.

Other subsystems rely on it to execute their own work. All new win 2 k applications (and most migrated applications) depend on the Win32 subsystem. Our upper-level general control software is closely related to the Win32 subsystem, so we need to pay enough attention to it. This article will also give a more detailed introduction.
The Win32 subsystem is responsible for the following:
Graphical User Interface visible to system users ). It implements and displays visual windows, dialogs, controls, and overall system styles.
Console I/O, including the keyboard, mouse, and display of the entire system.
The implementation of WIN32API is the interface between applications and other subsystems and the execution program. The Win32 subsystem has a special State in the system and inherent requirements for high performance, which is different from any other subsystem. Specifically, the Win32 sub-system is divided into components that run in user mode and components that run in INCORE mode. Generally, Win32 functions can be divided into the following three types:
User functions: Manage windows, menus, dialogs, and controls.
Graphical device interface (GDI, grarphic device interface) function to perform drawing operations on physical devices (screens and printers.
The kernel function manages non-Gui resources, such as processes, threads, files, and synchronization services.
In Windows 2 k OS, the user and GDI functions are moved into the kernel mode. Therefore, user processes requesting GUI services are directly sent to the kernel mode using system service interfaces. The kernel code that implements user and GDI functions resides in the wni32ksys module.

(2) The dos Virtual Machine (vdm) subsystem provides a 16-bit msdos environment for older dos applications.
(3) The Wow (Windows on Windows) subsystem supports 16-bit Windows applications (Windows 3.x ).
(4) POSIX (portable UNIX operation system interface) subsystem provides API support for uhix-style applications that comply with posix1003.1 source code standards.
(5) The OS/2 Subsystem creates an execution environment for 16-bit 05/2 applications.