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Information about Wow64

WoW64 (Windows-on-Windows 64-bit) is a subsystem of the Windows operating system that is capable of running 32-bit applications and is included on all 64-bit versions of Windows — including Windows XP 64-bit Editions, Windows Server 2003 x64 Edition and Windows Vista 64-bit Editions. WOW64 takes care of all the differences between 32-bit Windows and 64-bit Windows, particularly involving structural changes to Windows itself.

Translation libraries

The WOW64 subsystem is a lightweight translation layer that has similar interfaces on all 64-bit versions of Windows. Its primary purpose is to create a 32-bit environment that provides the interfaces required to allow 32-bit Windows apps to run unmodified in the 64-bit system. Technically, WOW64 is implemented using three dynamic-link libraries (DLLs): Wow64.dll, which is the core interface to the NT kernel that translates between 32-bit and 64-bit calls, including pointer and stack manipulations; Wow64win.dll, which provides the appropriate entry points for 32-bit apps; and Wow64cpu.dll, which takes care of switching the processor from 32-bit to 64-bit mode.

Architectures

Despite its outwardly similar appearance on all versions of 64-bit Windows, WOW64's implementation varies depending on the target processor architecture. For example, the version of 64-bit Windows developed for the Intel Itanium 2 processor (known at Microsoft as IA-64 architecture) uses Wow64win.dll to set up the emulation of x86 instructions within the Itanium 2's unique instruction set. That's a more computationally expensive task than the Wow64win.dll's functions on the x64 architecture, which switches the processor hardware from its 64-bit mode to compatibility mode when it's time to execute a 32-bit thread, and then handles the switch back to 64-bit mode. No emulation is required for WOW64 on x64.

The registry and the file system

The WOW64 subsystem also handles other key aspects of running 32-bit applications. For example, it's involved in managing the interaction of 32-bit apps with the Windows registry, which is somewhat different in 64-bit versions of the OS, and in providing an interface to the storage subsystem.

The operating system uses the %SystemRoot%\system32 directory for its 64-bit library and executable files. This is done for backwards compatibility reasons as many legacy applications are hardcoded to use that path. When executing 32-bit applications, WOW64 redirects requests for DLLs from that directory to %SystemRoot%\sysWOW64, which contains legacy libraries and executables.

See also

External links

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Microsoft Windows

Screenshot of Windows Vista Ultimate, the latest version of Microsoft Windows.
Company/developer: Microsoft Corporation
OS family: MS-DOS/9x-based, Windows CE, Windows NT
Source model: Closed source

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An operating system (OS) is the software that manages the sharing of the resources of a computer. An operating system processes system data and user input, and responds by allocating and managing tasks and internal system resources as a service to users and programs of the
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In computer architecture, 32-bit integers, memory addresses, or other data units are those that are at most 32 bits (4 octets) wide. Also, 32-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size.
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Microsoft Windows XP 64-bit Edition is a version of Microsoft's Windows XP operating system designed to run on Intel Itanium family of microprocessors in their native IA-64 mode.
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Windows Server 2003
(Part of the Microsoft Windows family)
Screenshot

Screenshot of Windows Server 2003 Enterprise Edition
Developer
Microsoft
Web site: www.microsoft.
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Windows Vista
(Part of the Microsoft Windows family)
Screenshot

Screenshot of Windows Vista Ultimate
Developer
Microsoft
Web site: Windows Vista: Homepage
Release information
Release date:
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System (from Latin systēma, in turn from Greek σύστημα systēma) is a set of entities, real or abstract, where each entity interacts with, or is related to, at least one other
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DLL is an abbreviation which can commonly mean:
  • Data link layer, a layer in the OSI network architecture model
  • Delay-locked loop, a device to reduce clock skew in digital circuits
  • Doubly-linked list, a data structure in computer programming

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Windows NT

Company/developer: Microsoft
Source model: Closed source / Shared source
Stable release: +/-
Preview release:
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kernel is the central component of most computer operating systems (OS). Its responsibilities include managing the system's resources (the communication between hardware and software components).
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pointer is a programming language data type whose value refers directly to (or “points to”) another value stored elsewhere in the computer memory using its address. Obtaining the value to which a pointer refers is called dereferencing the pointer.
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In computer science, a call stack is a special stack which stores information about the active subroutines of a computer program. (The active subroutines are those which have been called but have not yet completed execution by returning.
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CPU design is the design engineering task of producing a CPU, a component of computer hardware. It is a subfield of electronics engineering and computer engineering.

Overview

CPU design focuses on these areas:
  1. Datapaths (such as ALUs and pipelines)

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Intel Corporation

Public (NASDAQ:  INTC , SEHK: 4335 )
Founded 1968 1
Headquarters Santa Clara, California
 United States

Key people Paul S.
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Itanium 2
Central processing unit

Itanium 2 logo
Produced: From mid 2002 to present
Manufacturer: Intel
CPU Speeds: 733 MHz to 1.
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Microsoft Corporation

Public (NASDAQ:  MSFT )
Founded Albuquerque, New Mexico, USA (April 4 1975)[1]
Headquarters Redmond, Washington, United States

Key people Bill Gates, Co-founder and Executive Chairman ;
Paul Allen, Co-founder ;
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The generic term x86 refers to the "CISC" type instruction set of the most commercially successful CPU architecture[1] in the history of personal computing, used in processors from Intel, AMD, VIA, and others.
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instruction set is (a list of) all instructions, and all their variations, that a processor can execute.

Instructions include:
  • arithmetic such as add and subtract
  • logic instructions such as and, or, and not

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x86-64 is a 64-bit superset of the x86 instruction set architecture. The x86-64 instruction set natively supports Intel's x86 and was designed by Advanced Micro Devices (AMD), who have since renamed it AMD64.
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thread in computer science is short for a thread of execution. Threads are a way for a program to fork (or split) itself into two or more simultaneously (or pseudo-simultaneously) running tasks.
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To hard code or hard coding (also, hard-code/hard-coding, hardcode/hardcoding) refers to the software development practice of embedding input or configuration data directly into the source code of a program or other executable object, or fixed
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x86-64 is a 64-bit superset of the x86 instruction set architecture. The x86-64 instruction set natively supports Intel's x86 and was designed by Advanced Micro Devices (AMD), who have since renamed it AMD64.
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Windows on Windows, commonly referred to as WOW or WoW, is a name of two abstraction subsystems of Microsoft Windows operating system. WoW is a name of two critical components for backward compatibility of legacy code as Windows progresses.
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The following is a list of Microsoft Windows components.

Configuration and maintenance


Component Description Introduced
Control Panel
Control Panel Allows users to view and manipulate basic system settings and controls, such as adding hardware, adding and
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Windows Aero is the graphical user interface for Windows Vista, an operating system released by Microsoft in November 2006. Its name is an acronym for Authentic, Energetic, Reflective and Open.
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Desktop Window Manager (DWM, previously Desktop Compositing Engine or DCE) is a compositing window manager, introduced with Windows Vista, that enables the Windows Aero user interface. DWM requires graphics cards supporting DirectX 9.0 and Shader Model 2.0.
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Windows Explorer is an application that is part of modern versions of the Microsoft Windows operating system that runs on top of the Windows operating system and provides a graphical user interface for accessing the file systems, though is not integral to the running of a Windows
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In computing, the taskbar is a term for the application desktop bar which is used to launch and monitor applications in Microsoft Windows 95 and later versions (actually it's part of the Windows shell, see desktop shell replacement).
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Start Menu and Start Button are user interface elements in the Microsoft Windows product line, which serve as the central launching point for applications.

Traditionally, the Start Menu
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In computing, Windows Shell is the most visible aspect of the Microsoft Windows line of operating systems. The shell is the container inside of which the entire user interface is presented, including the Task bar, the Desktop, Windows Explorer, as well as many of the dialog boxes
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