Microsoft WINDOWS XP Professional X64 Edition English 64 Bit SP2c

Microsoft publicly released Windows XP Professional x64 Edition on April 30, 2005. This version of Windows XP Professional is the first designed specifically to work with x64 PCs. Windows XP Professional x64 Edition, a high-performance platform, brings benefits to customers who work in technical fields such as automobile and airplane design, computational fluid dynamics, and scientific visualization. Digital content creators, including 3-D animators, digital artists, and game developers will also welcome the large amounts of memory and performance improvements that make their 64-bit applications run faster and more efficiently. And enthusiasts who edit a large of amount of photos, video, or music files will benefit from the additional memory and processing capability.

In this column, I'll give you an overview of Windows XP Professional x64 Edition. I'll describe what hardware and software it supports and point out the kind of customer who'll get the most from the new OS version.

What is x64?
The term x64 is used to describe the 64-bit architecture developed by Advanced Micro Devices (AMD) and Intel to provide processors that are highly compatible with the x86 processors that have been the mainstay of personal computing. The x64 architecture, when combined with Windows XP Professional x64 Edition, can run the thousands of 32-bit programs available today. The x64 architecture also lets a developer enter whole new areas with the advanced capabilities that 64-bit processing makes possible.

The biggest difference between x64 and other 64-bit processors is that x64 processors are compatible at the hardware level with 32-bit, x86 processors. There are currently two basic x64 processor families:

• AMD's amd64
• Intel's EM64T

From AMD, this includes the Athlon 64, Athlon 64 FX, Mobile Athlon 64, Turion 64, and Opteron processors. From Intel, this includes the Xeon with EM64T and Pentium 4 with EM64T processors. The two architectures are binary compatible, allowing Windows XP Professional x64 Edition to use a single version to support both.

Description of Windows XP Professional x64 Edition
Windows XP Professional x64 Edition is a near feature-complete version of Windows XP Professional that runs on x64 processors. Windows XP Professional x64 Edition supports 128 GB of RAM and 16 terabytes of virtual memory address space, as compared to 4 GB of both physical RAM and virtual memory address space for 32-bit Windows XP Professional.

Windows XP Professional x64 Edition runs 32-bit applications in the Windows on Windows 64 (WOW64) subsystem providing compatibility with the more than 10,000 existing 32-bit Windows applications while enabling new 64-bit applications.

How to obtain Windows XP Professional x64 Edition
Windows XP Professional x64 Edition is only available from Microsoft manufacturer partners—such as Dell, HP, and IBM—as part of a new computer. There isn't a stand-alone retail version. System builders will offer the new version of the OS with new systems or, for customers who build their own computers, with a qualifying hardware purchase. An MSDN version is available to developers.

If you've already bought x64-capable hardware that you're using to run 32-bit Windows XP Professional, you'll have the option to trade in that copy of Windows XP Professional for a copy of Windows XP Professional x64 Edition. Check the Technology Advancement Program to find more information about this program.

Whatever version of Windows XP Professional x64 Edition you use, however, it will only be available as a fresh install. There is no provision for an upgrade from Windows XP Professional. If you're running Windows XP Home Edition and have x64 hardware, you can move to Windows XP Professional x64 Edition when it's available. But you'll need to upgrade from Windows XP Home Edition to Windows XP Professional Edition first.

Running 32-bit applications
32-bit applications running in the WOW64 subsystem provide a highly-compatible, high-performance environment for the thousands of existing 32-bit applications. 32-bit applications are installed into the Program Files (x86) directory structure, and have separate hives in the registry to prevent problems.

Applications running in the WOW64 system on Windows XP Professional x64 Edition each have a full 4 GB of virtual memory space. Applications compiled to take advantage of the /3 GB switch will actually get 4 GB, without constraining the operating system at all, since it is running in the 8 terabytes of virtual address space that Windows XP Professional x64 Edition has for the system processes. This can have a substantial impact on memory-constrained applications, such as computer-aided design (CAD) and computer-aided manufacturing (CAM), even before a 64-bit version of the program is available.

Running 64-bit and 32-bit applications side-by-side
With Windows XP Professional x64 Edition, you can run both 64-bit and 32-bit applications side by side. Your existing 32-bit applications run in WOW64, while the 64-bit applications run natively. This makes it easy to transition to 64-bit applications at your pace—only moving when you're ready. You can even run 32-bit and 64-bit versions of the same application in Windows XP Professional x64 Edition, allowing you to evaluate the new version of an existing application and transition at a controlled pace.

Who is the initial audience?
This release of Windows XP Professional x64 Edition is primarily designed for 32-bit system users who are pushing the memory limits of their systems and want the new 64-bit technology to improve their PC or workstation performance. The core audience for Windows XP Professional x64 Edition includes these groups:

• Developers
• Gamers
• Graphics, audio, and media artists
• CAD/CAM users
• Enthusiasts

I fall under this last one more than any other. I'm moving my main workstation to the new x64 box I built a few months ago. But one of the programs I've seen running on x64 that I find really exciting is SONAR 4, a professional music studio audio-mixing application from Cakewalk. As Ron Kuper, Chief Technical Officer for Cakewalk, discovered when they did an internal port of SONAR 4 to x64, they got a completely unexpected 20-30% performance boost even though SONAR 4 wasn't memory space constrained. But the additional efficiency of the x64 processor architecture, with its additional general purpose and floating point registers, had a significant impact on the speed and responsiveness of SONAR 4.

Making hardware decisions for the future
If you've bought a personal computer in the last few months, you may already have an x64-capable PC, just as I do. So all you need to do is participate in the Technology Advancement Program to get Windows XP Professional x64 Edition and you're ready to go. If you're buying a new desktop computer this year, I wouldn't even consider buying a non-x64 capable version, even if you choose to run 32-bit Windows on it. The cost differential between equivalent PCs is negligible or non-existent, and your new x64 PC will run either version of Windows XP quite well.

If you're buying a new system to run Windows XP Professional x64 Edition, you do need to be careful about the peripherals you choose. As with any new version of an operating system, there are still gaps in the list of supported hardware. New drivers are coming from all the major vendors, but these drivers will undoubtedly focus on only their newest products. And you can't run 32-bit drivers—they will not work.

Key differences
When moving to Windows XP Professional x64 Edition, you need to understand some key differences. The most important is that there is no support for legacy MS-DOS and 16-bit applications. If you have an older application that runs in MS-DOS mode or is a 16-bit application, you shouldn't move to Windows XP Professional x64 Edition until you can either update or replace the application.

Some 32-bit applications have 16-bit installation programs. Many of these will not install on Windows XP Professional x64 Edition, since 16-bit applications are not supported. However, some will work because Windows will transparently substitute the 32-bit version of the installer in the background.

Applications that install their own hardware drivers will not work until there is a 64-bit driver available for them. Windows XP Professional x64 Edition doesn't support 32-bit drivers at all.

Extensions to Windows Explorer, for example, menu extensions to the right-click menu in Windows Explorer, must be 64-bit. If they are 32-bit, the application may work, but the Windows Explorer extensions will not be available. This is because any application can be either 32-bit running in WOW64 or 64-bit. But not both. And Windows Explorer is obviously 64-bit. So the application itself will work, but the extensions won't. I really miss the right-click extensions for WinZip, a prime example of this.

All drivers must be 64-bit. There are still quite a few gaps in the list of available drivers but the situation should improve dramatically now that Windows XP Professional x64 Edition is officially launched. If you're buying new hardware, you should definitely make sure that there are x64 drivers available before you buy. And if you're recycling older peripherals to use with your new x64 computer, you'll want to check with the peripheral manufacturer or vendor about available drivers. One site I've found that has been quite helpful in finding drivers for x64 is PlanetAMD.