Windows NT and Unix OS
Chapter 2 : Appendix
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Significance: Designed from scratch incorporating all the
latest technologies available at that time.
Single user, multi-tasking
SMP : Symmetric multiprocessing
Graphical User Interface (Windows)
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Windows NT Architecture
NT can execute on a variety of hardware
Posix, Win32, OS/2, etc.
NT separates the application-oriented
software from OS software by an
elaborate module known as NT Executive.
NT execution operates in the kernel
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Highly modular, modified micro-kernel.
Well-defined API for each module allows
easy modification of functionality.
Hardware Abstraction Layer (HAL): maps
between command s and hardware. DMA,
Interrupt controller, SMP are supported at
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Microkernel consists of most fundamental
components of the operating system.
Process control, thread control, context
switching, scheduling, synchronization etc.
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IO manager, and Window Manager which
directly deal with harwdare.
Object manager, Security, process, virtual
memory, call manager: these modules go
System Services: interface to user-mode
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NT is partially OO.
Processes, files, threads, semaphores,
timers, windows are all designed as
Each object created has a handle (object
reference) and a security descriptor (SD).
Many other data structures used are not
classes or objects.
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Traditional Unix System
System call interface
Process Control subsystem
Device driver/ IO subsystem
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Modern Unix Kernel
System V release 4 (SVr4)
Berkeley Software Distribution (BSD 4.4)
Core facilities, + set of specific
functionalities (scheduler, vnode interface,
Virtual memory management, etc.)
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OS Topics Fig2.18
Process Description and Control
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