The OS contains a collection of small components that work together to perform different tasks. Each component provides a set of functions that act as an interface to the rest of the system. A process can be executed either in user mode or kernel mode. Architecture User Mode Provides Limited System Access User mode is an application execution environment. Software in user mode operates in a nonprivileged state with limited access to system resources.
All applications run in protected subsystems in user mode.
Kernel Mode Provides Unlimited System Access Kernel mode processes can access all hardware and sensitive system resources. This layer protects the rest of the Windows 2000 executive from the specific hardware, making the OS compatible with multiple processor architectures. This provides the life-support for one or more processors. It includes scheduling, interrupt, exception dispatching, and CPU synchronization. Addressability beyond 4 GB or 32 bit requires additional Intel processor architecture and API cooperation.