When AMD (Advanced Micro Devices) introduced the Athlon64 processor family in mid-2003, it started the race for 64-bit computing on the desktop. Earlier, Intel, maker of the reigning king of the desktop, the 32-bit Pentium processor, had introduced the 64-bit Itanium processor in 2000. But the Itanium was targetted for the server and high-end workstation market, which was then quite crowded considering that other manufacturers were already offering 64-bit processors for this market.

What other 64-bit processors are currently available?

Foremost among these 64-bit processor manufacturers were SUN with its SPARC and UltraSPARC processor which is used in various SUN servers and workstations. DIGITAL had its Alpha processor which was used in later DEC servers after the VAX but it was sold off to Compaq which then used them for their line of Alpha servers. MIPS used to produce its MIPS processors used in high-end workstations notably that of Silicon Graphics, (rumor has it that WindowsNT was developed by programmers using MIPS workstations) but it was later to evolve into embedded processors used for consumer products like handheld PCs, video games, and networking devices. The biggest is IBM with its behemoth Power4 processor, which had been the core of the processor family contributed by IBM to the PowerPC consortium consisting of Apple/IBM/Motorola/Texas Instruments. The Power4 processor is now used for some of the largest supercomputers currently running.

What 64-bit processors are available for the desktop?

AMD has brought out their Athlon64 processors intended for desktop computers and Opteron processors intended for multi-CPU workstations. Specialty computer builders have used the Athlon64 to make powerful desktop computers, mostly for high-end gaming machines. HP/Compaq has likewise offered Athlon64-based desktop computers. Earlier this year, APPLE introduced their Power Mac G5 with a 64-bit PowerPC processor chip. This brings 64-bit power to the Apple side of the desktop. Intel, which had been reluctant to release a 64-bit processor for the desktop market, now currently dominated by its 32-bit Pentium 4 processor, has finally announced it will do so this year, starting with a multi-processor Xeon chip to compete with AMD's similar Opteron chip. For those who revel in having the latest, they now have the chance to get the greatest in 64-bit computing for the desktop, that is, if they have the boodle for it, these powerful machines cost serious money, $1500 to $3500 or more.

But the Power Mac G5 isn't just about a new chip. The system also incorporates design makeovers, faster connections to main memory, and other component improvements. In addition, Apple has a 64-bit version of its Mac OS X , which gives the system an added boost (as of now, there's no 64-bit version of Windows XP although it is expected late this year).

Still, Apple lovers won't buy this system just because it has a 64-bit processor. By the same token, the computer isn't faster just because it runs at 64 bits. Despite Apple's claim that the G5 is "the world's fastest personal computer," IBM-compatible PC users haven't flocked to the new system. The reasons for buying a Mac remain fairly constant: ease of use, stability, and great graphics.

In the IBM-compatible PC camp, there are now plenty of 64-bit systems based on AMD's Athlon 64 family of 64-bit processors. Many of them are fully loaded gaming PCs from computer makers such as Falcon, Voodoo and Alienware. And HP/Compaq has also joined the AMD crowd, with its Presario 8000Z and Pavilion A550e series of computers.

In AMD's 64-bit lineup, the fastest option currently is the 2.4-GHz Athlon 64 FX-53 chip, which you'll often see in systems with fast DDR400 main memory, because this chip supports a speedy connection to main memory. Systems based on the Athlon 64 FX-53 have scored extremely well on applications-based benchmark tests, in fact, AMD Athlon 64-based PCs consistently score the fastest on these benchmarks, outperforming top-of-the-line PCs running Intel Pentium 4 chips in many tests.

But once again, you probably won't buy an Athlon 64-based system just for its processor. A 64-bit chip doesn't guarantee a better PC. Some tested Athlon 64-based PCs actually run slower than many 32-bit PCs.

What are the advantages of 64-bit processors?

The biggest advantage of a 64-bit system has nothing to do with clock speed, that megahertz rating that has long been the measure of a system's overall speed. The amount of data a chip can process at once is the key difference between today's 32-bit desktop processors, like Intel's Pentium 4, AMD's Athlon XP, and Apple's PowerMAC G4, and future 64-bit desktop CPUs, like Apple's PowerMAC G5 and AMD's Athlon 64.

Today's 32-bit Intel and AMD chips can address up to 4GB of memory (an Apple PowerMAC G4 unit can address 2GB). The 64-bit CPUs can handle more memory and larger files because it gives you a larger address space, which means it lets you address more memory, theoretically, up to 16 billion gigabytes.

Apple's new G5 machines will support up to 8GB of physical memory (twice as much as today's 32-bit systems), which should be plenty to keep the CPU busy without resorting to the slower virtual memory on a hard drive.

AMD says its new Athlon 64 processor will support up to one million gigabytes of physical memory. The first Athlon 64 motherboards will likely have 4 DIMM slots and, using 2GB DIMMS, the first systems could hold as much as 8GB of physical memory. That's a lot considering that, just half a decade ago, hard disks were maxing with that much storage capacity.

More memory means the system responds faster when working on certain applications. That's because the computer can access memory faster than it can hard disk, the more data a program can store in memory, instead of on the hard disk, the faster it will run. Such programs include those that access gargantuan databases, process large or complex video clips, and display rich graphics. Photo-realistic games, for instance, make good use of 64-bit computers, which is probably why companies that specialize in gaming systems have embraced 64-bit chips. So if you're a true-blue gamer, it behooves you to consider 64-bit PCs.

Who will benefit from 64-bit processing?

It's true a 64-bit desktop computer won't make your word processing program run faster. But a 64-bit chip has the power to dramatically improve the performance of your more demanding applications, such as audio and video encoding, complex engineering programs like CAD, and, of course, games. And in the long term, 64-bit computing will give programmers much more power to play with, and could revolutionize what desktop software can do.

However, less demanding applications, such as word processors, spreadsheets, e-mail clients, and Web browsers, the programs most people use on a daily basis, don't need to load tons of data into memory. If those are the main programs you use, you probably won't see a dramatic speed improvement from 64-bit technology, and which is why not all PC makers are offering 64-bit PCs today.

Once video editors watch a 64-bit PC encode video directly to a DVD on the fly, they'll want one. And once gamers see the cinematic quality that 64-bit chips help make possible, they'll want one.

Game makers, traditionally the first to make use of new technology, see clear advantages to 64-bit computing. That extra speed will let programmers add remarkable detail to their software, better textures, more realistic sounds, and larger and more realistic environments. Plus, the characters themselves will be rendered with dramatically more detail, more realistic features such as hair, skin, and eyes. And the computer-run characters will have more realistic artificial intelligence.

Some makers of game programs, like Epic Games, publisher of Unreal Tournament, have begun to update their game programs for use on a 64-bit system. The programs will be ready to go as soon as a compatible 64-bit OS arrives probably in 2005.

Video encoding will also improve in a 64-bit world. For example, the DivX codec program compresses DVD-quality video up to ten times more than the MPEG2 standard, making it easier to transmit over the Internet. A 64-bit processor will improve both the encoding and decoding of video with speeds resulting in more frames per second and a more film-like playback.

Eventually the benefit will go far beyond speed. The key to 64-bit computing is that it will open up possibilities for creative programmers in ways never before seen.

What else are needed to support 64-bit computing on the desktop?

To take advantage of those 64-bit systems, you'll need a 64-bit-capable desktop operating system. You will also need new 64-bit-capable hardware drivers, and 64-bit applications. That's where things get more complicated, and the Apple and AMD camps differ. Apple supplies their own while AMD (and Intel) depend on other companies to provide the OS and applications.

Apple's latest OS X has 64-bit extensions, providing their new PowerMAC G5 systems and a handful of optimized apps a taste of greater power. When Apple rolls it out, it will include an updated version of the current 32-bit OS X operating system code-named Jaguar, which will support 32-bit applications with the ability to make 64-bit requests from the processor. But that isn't quite enough to give Apple a wholesale performance edge. Apple hasn't announced plans for a pure 64-bit operating system; Panther, an updated 32-bit OS due out the end of this year, will have 64-bit support like Jaguar.

Several Linux distributions, notably Red Hat and SuSe, now support the Athlon 64, but Microsoft's Windows XP 64-Bit Edition for 64-bit Athlons won't arrive until late this year. Aside from a handful of expected applications, such as DivXNetworks' DivX video encoder and Epic's Unreal Tournament, 64-bit desktop software will be an even longer wait. The lack of full software support is one reason Intel hesitated introducing a 64-bit desktop chip.

AMD's Athlon 64 processor will work like previous Athlon chips under the current 32-bit Windows XP, but the OS does not support the chip's 64-bit capabilities. That will have to wait until Microsoft ships its as-yet-unnamed 64-bit version of Windows XP for the Athlon 64, that OS will support both 32-bit and 64-bit applications for AMD's Athlon 64 and Intel's upcoming 64-bit successor to the Pentium. However, Microsoft has not said when it will ship the OS ....

Once Windows catches up, there's still the issue of making today's PC hardware 64-bit ready, such as, new software drivers for all of your key components [e.g. graphics cards, hard drives, sound cards and the like], all the stuff that the operating system needs to work well.

And then, finally, come the 64-bit-ready applications. AMD admits the transition from 32 to 64 bits in everyday desktop applications won't happen overnight. But by putting 64 bits into its upcoming processors, AMD is preparing for the future.

In Conclusion...

History shows transitions like this do take time. Back in 1985 when Intel launched its 386 processor, a 32-bit chip that also ran 16-bit code, AMD claimed the extra bits weren't yet necessary. And Windows didn't become a pure 32-bit OS until a decade later. Now the shoe is on the other foot, AMD has introduced the 64-bit chip and Intel claims the extra bits aren't really needed yet.

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