Operating System Model

• Windows is a multi-user operating system, where application is separated from the OS.

• The kernel code runs in the privileged mode also known as the kernel mode.

  • Kernel mode has access to all the system data and hardware

• The user application runs in the non-privileged mode also known as user mode.

  • User mode has limited access to the system data.

• The user mode, when requires system service, the system service executes a special instruction (interrupt), switches the thread to the kernel mode.

• Windows kernel is monolithic in nature like most UNIX kernels.

• Which means that, OS, kernel code and the device drives, all share the same kernel-mode protected memory space.