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A Roundup of 64-Bit Computing

Confused about whether x86 64-bit servers, workstations and desktops are the way for your business to go? You're not the only one.

RISC-based chips have supplied the IT sector with 64-bit technology for some time. Powerful processors made by IBM, Sun, Texas Instruments and others are a mainstay of mainframes, Unix servers and even gaming platforms (Nintendo 64).

Yet 64-bit computing technology for x86-based architecture is relatively untapped in the enterprise. In this edition of In Focus, our ongoing series of emerging trends that help you get updated quickly, internetnews.com provides an executive summary of 64-bit computing, the players and how it may impact your enterprise computing plans.

Back to the Future: 64-Bit

The technology has been hot discussion topic with the IT set ever since AMD debuted its Opteron processor two years ago. But 64-bit computing is not exactly a new hot topic. DEC (Digital Equipment Corporation) is widely credited breaking into the market with its Alpha 64-bit processor (for RISC-based architecture), released in 1992.

But timing is always a key factor with adoption. Fast-forward to 2005; 64-bit is gaining momentum, thanks to an old-fashioned horse race between AMD and Intel .

Both sides have been ramping up their efforts to push the envelope beyond their workhorse 32-bit processors. Both companies also have multi-core architecture strategies in their roadmaps, which gives x86 64-bit architectures plenty of room to grow.

And while analysts suggest there is no "there, there" yet for applications running on x86 64-bit, the time is fast-approaching. This is in large part because of Microsoft's goal of becoming a data center superpower.

The gods of Redmond have made it their mission to make sure AMD and Intel are on track to deliver mass quantities of x86 64-bit processors in order to support its 64-bit versions of Windows Server, SQL Server and others.

Oracle and SAP are two other major players that have invested time and money into porting their applications to x86 64-bit.

Of the major OEM's HP is heavily invested in both Intel's and AMD's 64-bit strategy. Sun Microsystems and IBM support both chipmakers but tend to favor AMD and Intel designs respectively.

Dell remains the lone Intel holdout and refuses to accept AMD products into its lineup barring a massive customer revolt and/or exodus.

What's in a 64-bit name?

AMD calls it AMD64, Intel calls its version EM64T. Despite their best efforts to brand x86 64-bit architectures with their name on it, it is Microsoft that is actually defining the marketing game.

Early on, Microsoft dubbed the technology Windows on Windows 64 (WOW64), but the company is playing the middle ground by identifying x86 64-bit technology as x64. OEMs like Sun and HP have also started referring to their x86 64-bit strategies as x64.

The different factions have also come to define the term to mean that 32-bit applications are backwards-compatible, which ensures a safe migration path to 64-bit operating systems.

What's under the hood?

The term 64-bit in chips means that the CPU can process 64 different instructions at the same time - think of 64 lanes on a freeway. A 32-bit chip can process half of that, but the doubling of instructions does not mean that 64-bit chips are faster than 32-bit counterparts.

Advocates say the ability to handle larger problems directly in primary memory is the major performance benefit of 64-bit machines. There is also a greater proportion of a database can live in primary memory.

With 64-bit, larger CAD/CAE (computer aided design) models and simulations can fit in primary memory, larger scientific computing problems can fit in primary memory, and Web caches can hold more in memory, reducing latency.

AMD designed its 64-bit processors with an integrated memory controller -- a 128-bit, dual-channel design supporting DDR266 and DDR333 SDRAM. The chips also offer support for SSE, SSE2, MMX, 3DNow! technology and legacy x86 instructions.

The Opteron series, for example, has 64-bit integer registers, 48-bit virtual addresses, 40-bit physical addresses, eight new 64-bit integer registers (16 total) and eight new 128-bit SSE/SSE2 registers (16 total).

The chips also include AMD's HyperTransport technology to I/O devices complete with three links, 16-bits in each direction. Each supports up to 1600 MT/s or 3.2 GB/s in each direction. Each link can connect to an I/O device or another processor.

Intel's EM64T is another story.

EM64T is an extension of the 32-bit x86 or IA-32 instruction set. The shift to 64-bit processors was always possible for Intel, but the question had always been whether or not the company would extend the technology and put it in direct competition with Itanium.

"Once you can get the 64-bit technology in a Pentium, the higher priced Itanium seems outdated," Industry analyst Rob Enderle told internetnews.com.

Intel EM64T can access larger amounts of memory. They can handle 64-bit flat virtual address space, 64-bit pointers, 64-bit wide general purpose registers, 64-bit integer support and up to 1 terabyte (TB) of platform address space. Chips with the technology can support 64-bit capable operating systems from Microsoft, Red Hat and SUSE.

However, EM64T cannot run the same software written for Itanium.

The company started out with the code-name Yamhill, which quickly became CT or Clackamas Technology. Then Intel came up with IA-32E (IA-32 Extensions) but eventually settled on EM64T. The first EM64T was Intel's Xeon code-named Nocona.

The other issue is that Intel maintains a healthy 32-bit processor lineup with its Pentium desktop processors and its workhorse Xeon server chips and the company has its 64-bit EPIC-architecture Itanium family. So the need for Intel to evolve Pentium or Xeon to 64-bit status was a bit of a quagmire for Intel.

During an Intel Developer's Forum in 2004, incoming Intel CEO Paul Otellini and then company CTO Pat Gelsinger suggested that the need to move to 64-bit was not even necessary until at least until 2006 or 2007. Any move prior to that might be considered premature at best, Gelsinger said at the time considering 32-bit addressing limit of 4GB seems to be doing just fine in the marketplace.

Otellini acknowledged that the cost of memory to support 64-bit systems could price a desktop PC somewhere between $2,000 and $3,000, but said eventually there would be price drops.

"Just like we went from 16 to 32-bits, the memory requirements grow over time on applications, just as memory costs come down over time," Otellini said. "So at some point it becomes very economical."

The master plan now is to overlap the 64-bit Xeon and the 64-bit Itanium. The company has even hinted that the motherboard support for Xeon and Itanium would become the same, making it easier for OEM's to build systems.

When should you jump?

Gartner , for one, believes 64-bit systems will start becoming necessary around the end of 2005 as more applications demand memory systems larger than 32-bit systems can handle. The Stamford, CT-based analyst firm also projects 64-bit systems will become mainstream by 2007.