Overview of Windows XP 64-Bit Edition | Microsoft Windows XP Professional Resource Kit 2003

Windows XP 64-Bit Edition supports the latest class of Intel Itanium processors designed for users who need to create and manipulate large amounts of complex data. The high performance of the Intel Itanium processor is targeted toward high-end workstation applications such as large database management, data mining, computer-aided engineering, digital content creation, and scientific and engineering computing. Itanium-based computers running Windows XP 64 Bit Edition can support up to 16 terabytes of virtual memory and up to 16 gigabytes (GB) of physical memory.

Based on the Explicitly Parallel Instruction Set Computing (EPIC) design technology, the Intel Itanium processor can perform up to 20 operations simultaneously by using advanced compiling techniques and large processor resources. In addition, applications can preload substantial amounts of data into virtual memory to enable rapid access by the processor. This reduces the time for loading data into virtual memory and the time for seeking, reading, and writing data to storage devices, thereby allowing applications to run faster and more efficiently.

Using an emulation layer, you can run 32 bit applications on Windows XP 64-Bit Edition. However, such applications run significantly slower on the 64-bit system than on the 32 bit system, because emulation requires additional resources.

Table H-1 describes the architectural differences between Microsoft Windows XP Professional and Windows XP 64 Bit Edition.

Table H-1: Architectural Comparison of Windows XP Professional and Windows XP 64 Bit Edition
Architectural Component	Windows XP Professional	Windows XP 64-Bit Edition
Virtual memory	4 gigabytes (GB)	16 terabytes
Paging file size	64 GB	512 terabytes
Paged pool	470 megabytes (MB)	128 GB
Non-paged pool	256 MB	128 GB
System cache	1 GB	1 terabytes
System Page Table Entry (PTE)	1.2GB	128GB

For more information about migrating applications to 64-bit, see the Software Development Kit (SDK) information in the MSDN Library link and the Driver Development Kits link on the Web Resources page at http://www.microsoft.com/windows .