.NET Framework version 1.1 for 64-bit operating systems

Applies To: Windows Server 2003 with SP1

What does the .NET Framework do?

The .NET Framework is a new computing platform designed to simplify application development in the highly distributed environment of the Internet. The .NET Framework has several main components: the common language runtime, the .NET Framework class library, and the runtime hosts. The common language runtime is the foundation of the .NET Framework. It manages code execution and provides core services such as memory management, thread management, and remote execution. The .NET Framework class library is a comprehensive, object-oriented collection of reusable classes that you can use to develop a wide range of applications, including ASP.NET applications and XML Web services. The .NET Framework also provides several runtime hosts, including Windows Forms and ASP.NET, which work directly with the runtime to provide a scalable, server-side environment for managed code.

In the previous release of the 64-bit versions of the Microsoft Windows Server 2003 operating systems and Microsoft Windows XP Professional x64 Edition operating system the .NET Framework was not supported. In the 64-bit versions of Windows Server 2003 Service Pack 1 and Windows XP Professional, the .NET Framework is supported. The Microsoft .NET Framework 1.1 is built into all products in the Windows Server 2003 family except for the 64-bit versions.

The 32-bit version of .NET Framework 1.1 is supported by 64-bit versions of Windows Server operating systems and can be installed for 32-bit applications running on 64-bit versions of Windows operating systems (WOW64).

To install .NET Framework 1.1, visit Windows Update and select the .NET Framework 1.1 package or see "Microsoft .NET Framework Version 1.1 Redistributable Package" at the Microsoft Download Center Web site at https://go.microsoft.com/fwlink/?LinkId=17153. To install the service pack, visit Windows Update or see "Microsoft .NET Framework 1.1 Service Pack 1" at the Microsoft Download Center Web site at https://go.microsoft.com/fwlink/?LinkId=39058.

Important performance and scalability information for Itanium-based systems

If a 32-bit version of the .NET Framework is installed on 64-bit Itanium-based systems, applications created for the 32-bit version of the Framework will bind and run against it. Therefore, applications created with the Microsoft .NET Framework 1.1 run only in a 32-bit process within the WOW64 compatibility environment. Due to the design of x86 emulation and the WOW64 subsystem for the Itanium processor family applications are restricted to execution on one processor.

Single processor execution and x86 emulation reduce the performance and scalability of 32-bit .NET Framework applications running on Itanium-based systems. We recommend that applications using the .NET Framework 1.1 be used for interactive, client applications. We do not recommend this environment for .NET Framework 1.1 applications that demand high performance or scalability, such as high-load ASP.NET applications. We suggest that application developers instead evaluate the .NET Framework 2.0, which includes native 64-bit support for Itanium-based systems, for increased performance and scalability.

Who does this feature apply to?

This feature applies to users with applications written to use the .NET Framework 1.1 and also to application developers developing .NET Framework 1.1 applications that will be run on both 64-bit and 32-bit operating systems.