Windows NT Operating System Junhua Duan Junhua Duan Aug. 26th, 1999 Aug. 26th, 1999

What is an operating system? An operating system is a computer program that provides an environment in which other computer programs can run, allowing them to easily take advantage of the processor and of I/O devices such as disks.

Services Provided by Operating System Hardware Shielding Resources Sharing

Windows NT Models Layered ModelLayered Model Client/Server ModelClient/Server Model Object ModelObject Model Symmetric MultiprocessingSymmetric Multiprocessing

Layered Model Application Program Application Program System Services File System Memory and I/O Device Management Processor Scheduling Hardware User Mode Kernel Mode

Client/Server Model Memory Server Client Application Network Server Process Server File Server Display Server kernel Hardware Send Reply

Windows NT’s Client/Server Structure Win32 Client OS/2 Client POSIX Client Win32 Subsystem OS/2 Subsystem POSIX Subsystem Executive Hardware Kernel

Object Model An object is a data structure whose physical format is hidden behind a type definition. It embodies a set of formal properties and is manipulated by a set of services. Windows NT uses objects to represent system resources. Any system resource that can be shared by more than one process is implemented as an object and manipulated by using object services.

Symmetric Multiprocessing Memory Operating System User Thread User Thread User Thread User Thread Operating System I/O Devices(Monitor,Mouse,Keyboard) Processor A Processor B

Asymmetric Multiprocessing Memory Operating System User Thread User Thread I/O Devices(Monitor,Mouse,Keyboard) Processor A Processor B User Thread

Windows NT Structure Protected SubsystemsProtected Subsystems NT ExecutiveNT Executive

Protected Subsystem Environment subsystemEnvironment subsystem Integral subsystemIntegral subsystem

Executive Components Object ManagerObject Manager Security Reference ManagerSecurity Reference Manager Process ManagerProcess Manager Virtual Memory ManagerVirtual Memory Manager I/O and File SystemI/O and File System KernelKernel Hardware abstraction layer(HAL)Hardware abstraction layer(HAL)

Main Features ExtensibilityExtensibility PortabilityPortability ReliabilityReliability CompatibilityCompatibility

Extensibility Protected subsystemsProtected subsystems Modular StructureModular Structure Object representation of resourcesObject representation of resources Loadable driversLoadable drivers RPC facilityRPC facility

Portability Portable CPortable C Processor isolationProcessor isolation Platform isolationPlatform isolation

Reliability Structured exception handlingStructured exception handling Modular designModular design New NT file systemNew NT file system C2 security architectureC2 security architecture Virtual memoryVirtual memory

Compatibility Program compatibilityProgram compatibility File System compatibilityFile System compatibility

Conclusion Windows NT is a symmetric multiprocessing operating system which support multiple operating system environments. It has a Windows graphical user interface and runs Win32, 16-bit Windows, MS-DOS, POSIX, and OS/2 program. It employs advanced operating system principles such as virtual memory, preemptive multitasking, structured exception handling, and operating system objects. It is secure, powerful, reliable, and flexible.