64-bit computing

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64-bit computing

CPUs that process 64 bits as a single unit, compared to 8, 16 or 32. Today's fastest computers are 64-bit machines; however, they are not twice as fast as 32-bit computers, because the 64 bit "word size" relates to only one aspect of internal processing. The CPU's clock speed, along with the speed, size and architecture of the disks, memory and peripheral bus all play important roles in a computer's performance (see throughput). In many cases, the perceived difference can be negligible. See word.

More Memory
A major advantage to 64-bit operating systems is that they support more memory than a 32-bit OS, which is typically limited to 4GB. For example, while the 32-bit version of Windows 7 Professional handles 4GB, the 64-bit version supports up to 192GB. See PAE.

A Lot of 32-Bit Software
Although CPUs migrated to 64-bits years ago, the vast majority of people still run 32-bit operating systems and applications in their 64-bit personal computers.

New versions of Windows come in 32-bit and 64-bit versions, and Apple upgraded OS X for the Mac entirely to 64 bits in 2009 (see Snow Leopard). The complete migration from 32-bit applications to their 64-bit counterparts may take many years. For example, people still run 16-bit DOS and Windows applications in their PCs that were written more than two decades ago. This is why some users opt to install the 32-bit version of Windows, because 64-bit Windows does not run 16-bit apps natively (see Windows XP Mode). For examples of 64-bit hardware, see Intel 64, AMD64, Opteron and Athlon. See 32-bit computing and bit specifications.

References in periodicals archive ?
Appro's cutting-edge 1U-1142H server based on Quad AMD Opteron processors will double the density of their current 1U servers and provide best-in-class processor performance for 32-bit applications, with easy transition to 64-bit computing," said Ben Williams, director of the Server/Workstation Business Segment at AMD.
The certification process with ATI ensures that our customers can depend on the increased functionality of 64-bit computing.
InfoWorld named Fred Weber, AMD CTO, to its list of Innovators of 2005 for innovations to the AMD roadmap that comprehended the need for 64-bit computing and dual-core processors back in 1999.
AMD's x86-64 architecture extends x86, the industry's most widely supported instruction set, and is designed to enable 64-bit computing while remaining compatible with existing 32-bit software infrastructure and industry experience.
1 release to add support for leading 64-bit computing architectures that include Intel's Itanium and Xeon EM64T, and AMD Opteron.
As 64-bit computing continues to gain momentum we want to make sure that our customers stay protected as they migrate to this new architecture.
AMD's x86-64 technology is a straightforward approach to 64-bit computing.
Moreover, AMD64 technology protects companies' software investments by enabling a seamless migration from 32- to 64-bit computing as business needs evolve.
We think this release represents a fundamental leap in terms of processing power and presents a new option for companies looking to install enterprise-ready Linux 64-bit computing solutions.
Windows XP Professional x64 Edition running on Alienware MJ-12 7550a workstations provides customers with the significantly enhanced performance, reliability and security that comes with 64-bit computing," said Brian Marr, senior product manager of Windows at Microsoft Corp.
The x86-64 technology extends the x86 instruction set to enable 64-bit computing and is the backbone behind AMD's planned 64-bit processor family, code-named "Hammer.