Understanding 64-Bit Computing

Since it was introduced for Windows operating systems, 64-bit computing has changed substantially. Not only do computers running 64-bit versions of Windows perform better and run faster than their 32-bit counterparts, they are also more scalable because they can process more data per clock cycle, address more memory, and perform numeric calculations faster. Windows 7 supports two different 64-bit architectures:

� x64 This architecture is based on 64-bit extensions to the x86 instruction set, which is implemented in AMD Opteron (AMD64) processors, Intel Xeon processors with 64-bit extension technology, and other processors. This architecture offers native 32-bit processing and 64-bit extension processing, allowing simultaneous 32-bit and 64-bit computing.

� ia64 This architecture is based on the Explicitly Parallel Instruction Computing (EPIC) processor architecture, which is implemented in Intel Itanium (IA64) processors and other processors. This architecture offers native 64-bit processing, allowing 64-bit applications to achieve optimal performance.

Sixty-four-bit computing is designed for performing operations that are memory intensive and that require extensive numeric calculations. With 64-bit processing, applications can load large data sets entirely into physical memory (that is, RAM), which reduces the need to page to disk and increases performance substantially. The EPIC instruction set enables Itanium-based processors to perform up to 20 operations simultaneously.

Currently, the prevalent firmware interfaces are:
� Basic input/output system (BIOS)
� Extensible Firmware Interface (EFI)
� Unified Extensible Firmware Interface (UEFI)

Itanium-based computers differ in many fundamental ways from computers based on the x86 and x64 specifications. While Itanium-based computers use EFI and the GUID partition table (GPT) disk type, computers based on x86 use BIOS and the master boot record (MBR) disk type. Computers based on x64 use UEFI wrapped around BIOS or EFI. This means that there are differences in the way you manage computers with these architectures, particularly when it comes to setup and disk configuration. However, with the increasing acceptance and use of UEFI and the ability of Windows 7 to use both MBR and GPT disks regardless of firmware type, the underlying chip architecture won�t necessarily determine what firmware type and disk type a computer uses. This decision is in the hands of the hardware manufacturer.

Source of Information : Microsoft - Windows 7 Administrators Pocket Consultant 2010