32-bit preemptive multitasking operating system for Intel microprocessors.
Key goals for the system:
3. POSIX compliance
4. multiprocessor support
6. international support
7. compatibility with MS-DOS and MS-Windows applications.
Uses a micro-kernel architecture.
Available in four versions, Professional, Server, Advanced Server, National Server.
In 1996, more NT server licenses were sold than UNIX licenses
In 1988, Microsoft decided to develop a “new technology” (NT) portable operating system that supported both the OS/2 and POSIX APIs.
Originally, NT was supposed to use the OS/2 API as its native environment but during development NT was changed to use the Win32 API, reflecting the popularity of Windows 3.0.
1.Extensibility — layered architecture.
2.Portability — 2000 can be moved from on hardware architecture to another with relatively few changes.
library (DLL) called the “hardware abstraction layer” (HAL).
Silberschatz, Galvin and Gagne 2002 21.5 Operating System Concepts
3. Reliability — 2000 uses hardware protection for virtual memory, and software protection
mechanisms for operating system resources.
4. Compatibility — applications that follow the IEEE 1003.1 (POSIX) standard can be complied
to run on 2000 without changing the source code.
5. Performance — 2000 subsystems can communicate with one another via high-performance
6. International support — supports different locales via the national language support
Layered system of modules.
Protected mode — HAL, kernel, executive.
User mode — collection of subsystems
1. Environmental subsystems emulate different operating systems.
2. Protection subsystems provide security functions.
Depiction of 2000 Architecture
Foundation for the executive and the subsystems.
Never paged out of memory; execution is never preempted.
Four main responsibilities:
1. thread scheduling
2. interrupt and exception handling
3. low-level processor synchronization
4. recovery after a power failure
Kernel is object-oriented, uses two sets of objects.
1. dispatcher objects control dispatching and synchronization (events, mutants, mutexes,
semaphores, threads and timers).
2. control objects (asynchronous procedure calls, interrupts, power notify, power status,
process and profile objects.)