An Overview Of Windows NT System

Student: Yifan Yang

Student ID: 102525

#1. Windows NT Models a>. Client / server model

b>. Object model

c>. Symmetric multiprocessing

#2. Windows NT Structure a>. Protected subsystems

b>. Executive

#4. Additional Windows NT Architectures a>. Internationalization

b>. Structured exception handling

#3. A Brief Tour a>. Logon session

b>. Environment subsystems

c>. Native services

d>. Objects

e>. Virtual memory

f>. I/O and file systems

#1. Windows NT Models• What is an OS Model? It is a broad framework that unifies

the many features and services the system provides and the tasks it performs.

• a>. Client / Server model

• Windows NT system: Combination of Layered model and client / server model.

• Layered model is one which divides the O/S into modules and layers them one on top of the other. Each module provides a set of functions that other modules can call.

• Benefits for using client / server model• Simplifies the base OS, the executive.• Improves reliability.• Lends itself well to a distributed computing model.

Application Program

System Services

Application Program

File System

Processor Scheduling

Hardware

Memory and I/O Device Management

User Mode

Kernel Mode

...

Layered Operating System

• a>. Client /Server model

• Is one which devices OS into several processes, each of which implements a single set of services.

Client Application

MemoryServer

NetworkServer

ProcessServer

FileServer

DisplayServer

Microkernel

Hardware

Client /Server Operating System

Reply

Send

• b>. Object model

• Object model Is one that any system resources such as files, shared memory and physical devices is implemented as an object and manipulated by using object services so that resources can be shared by more than one process.

• Benefits for using object model• OS can access and manipulate its resources uniformly.• Security is simplified because all objects are protected in the same way.• Objects provide a convenient and uniform paradigm for sharing resources between two or more processes.

OperatingSystem

OperatingSystem

UserThrea

dUser

Thread

UserThread

UserThrea

d

Processor A Processor B

Memory

Monitor Mouse Keyboard I/O Devices

Symmetric Multiprocessing

• c>. Symmetric multiprocessing• Symmetric multiprocessing is to allow OS running on any free processor or on all processors simultaneously, sharing memory among them.

• Benefits for being multiprocessing system• Ability to run OS code on any available processor and on

multiple processors at one time.

• Multiple threads of execution within a single process.

• Server processes that use multiple threads to process requests from more than one client simultaneously.

• Convenient mechanisms for sharing objects between processes and flexible interposes communication capabilities, including shared memory and an optimized message-passing facility.

#2. Windows NT Structure• The Windows NT’s structure can roughly be divided into

two parts: the user-mode portion (protected subsystems) and kernel-mode portion (NT executive).

Object SecurityManager Reference

Monitor

ProcessManager

LocalProcedure

Call Facility

VirtualMemoryManager

I/O Manager File Systems

Cache Manager

Device DriversNetwork Drivers

Kernel

Hardware Abstraction Layer (HAL)System Trap

User ModeKernel Mode

OS/2Subsystem

Win32Subsystem

POSIXSubsystem

System Services

NT Executive

Securitysubsystem

LogonProcess

OS/2Clien

tWin32Client

POSIXClient

Hardware

Applications

ProtectedSubsystems(Servers)

Message Passing

Hardware Manipulation

a>. Protected subsystems (environment and integral)

b>. ExecutiveExecutive components and their responsibilities:

Object SecurityManager Reference

Monitor

ProcessManager

LocalProcedure

Call Facility

VirtualMemoryManager

I/O Manager

File Systems

Cache Manager

Device Drivers

Network Drivers

Kernel

Hardware Abstraction Layer

System ServicesInternal Interfaces

System Interfaces

#3. A Brief Tour

a>. Logon session

LogonProcess

SecuritySubsystem

Win32Subsystem

User Mode

Local Procedure Call (LPC)

Logging On

b>. Environment subsystems

Each of the environment subsystems supplies an API that its clientapplications use.

Win32Client

Win32

Client

POSIX

Client

OS/2Client

16-Bit Windows

Environment

MS-DOSClient

Win32Subsyste

m

POSIXSubsyste

m

OS/2Subsyste

m

Graphical I/O

Character I/O

…………………………………..

……………...

………………….

Virtual DOSMachines(VDMs)

User Mode

Kernel Mode

Character I/O

Character I/O

Local Procedure Call (LPC)

Environment Subsystems and Client Applications

c>. Native services They are system services provided by individual components of the NT

Object SecurityManager Reference

Monitor

ProcessManager

LocalProcedure

Call Facility

VirtualMemoryManager

I/O Manager

File Systems

Cache Manager

Device Drivers

Network DriversKernel

Hardware Abstraction Layer

System Trap

Native System Service Call

executive.

User Mode

Kernel Mode

OS/2Subsystem

Win32Subsystem

POSIXSubsystem

System Services

Many NT native services are object services.

Object Security

Manager ReferenceMonitor

ProcessManager

LocalProcedure

Call Facility

VirtualMemoryManager

I/O Manager

File Systems

Cache Manager

Device Drivers

Network DriversKernel

Hardware Abstraction Layer

User Mode

Kernel Mode

Win32Subsystem

System Services

d>. Objects

Create process Create file

Create object

Create object

Creating NT Objects

e>. Virtual memory

addresses in a flat/linear address space.The NT memory architecture is virtual memory based on 32-bit

System(2 GB)

User CodeAnd Data

(2 GB)

Resident OperatingSystem Code

……………………….

Nonpaged

Paged

Physical Addressing Range

Paged

FFFFFFFFh

80000000h

7FFFFFFFh

00000000h

NT Address Space Layout

Object SecurityManager Reference

Monitor

ProcessManager

LocalProcedure

Call Facility

VirtualMemoryManager

I/O Manager

Kernel

System Services

User Mode

Kernel Mode

FAT FileSystem Driver

NTFSDriver

HPFSDriver

FloppyDisk Driver

HardDisk Driver

Layered Drivers

Synchronous as well as asynchronous I/O. Windows NT supports FAT,

f>. I/O and file systems

...

HPFS and NTFS.

#4. Additional / Windows NT Architectures

• a>. Internationalization

• A Locale consists of a language, a country, a code set, the binary codes used to represent the characters of a particular language.

• To facilitate localization, Windows NT’s Win32 subsystem provides a national language support (NLS) API.

• Unicode, a 16-bit character-coding scheme, can represent 65,536 characters so that it is enough to include all languages in computer commerce today.

FFFFh0000h

ASCII

Arabic andHebrew scripts

Dingbats (graphical symbols)Math/technical symbols

Punctuation

ideographsChinese/Japanese/Korean

Unified

Application usePrivate

Compatibilityzone

Indic scriptsOthers

Latin,Greek,

Cyrillic, and

Armenian scripts

Chinese/Japanese/Korean symbols

(Bopomofo,Hiragana,Katakana,

Hangul,…)

Future use

Provides compatibility with standard, non-Unicode character sets

Unicode Layout

• b>.Structured exception handling

• Structured exception handling is the met hod used in windows NT for processing both hardware and software exceptions, using the control structure of a programming language.