The future of 64-bit computing on the home and enthusiast fronts looks brighter after some announcements by Intel earlier this month.

Years ago, Intel set out on a processor development path that would have had consumers switching from the IA-32 architecture (based on the x86 instruction set) to the IA-64 architecture (based on the EPIC instruction set). The IA-64 architecture was designed from scratch, using lessons learned about the limitations of the IA-32 architecture. IA-64 chips should be very efficient. This is borne out by the SPEC_int and SPEC_fp 2000 scores of the 1.5 GHz Itanium 2 processors, which are almost twice as good (fast) as those of the 3.0 GHz Pentium 4 0.13 micron processors. On the other hand, switching to the new IA-64 architecture would have required consumers to buy all new software (or 64-bit upgrades to all their software), which would cost a huge amount. The cost of software upgrades reflects the cost to software developers of having to port their applications to a new processor instruction set and a new 64-bit operating system (OS). And of course, software developers would not lose the chance to charge customers a little (?) extra for the touted benefits of moving to 64 bits.

However, Intel had not bargained for AMD'S strategy. A few years ago, when it seemed Intel would steamroller over AMD, the latter managed to pull a rabbit out of its hat, in the form of the Athlon XP processor, a processor that took the performance lead from Intel. Later, Intel once again caught up with AMD, and has recently been once again speeding past AMD. AMD has managed to yet again pull a rabbit out of its hat. And it seems this rabbit has legs. It is the AMD64 architecture, and it currently manifests itself as the Opteron (server market) and AMD FX-51 (home / small-office market) processors, all of them 64-bit chips. In going to 64 bits, AMD chose to extend the old 32-bit x86 instruction set. This way, all the current software, including the 32-bit operating systems, would run on the 64-bit chips. When 64-bit software becomes available in the future, consumers could move to 64-bit software as and when their budgets permitted. Of course, the down side would be that the processors would inherit some of the design inefficiencies of the x86 instruction set. You can see from the SPEC benchmarks that the AMD64 chips are not as speedy as the Itanium 2 chips. However, on real world tests as reported in computer magazines, the AMD FX-51 chips do beat the fastest Pentium 4 chips on most tests.

When Intel came to know of AMD's strategy, they retrofitted the Itanium chip design with the ability to execute 32-bit x86 code, so as to be able to run current 32-bit software. However, this is done by on-the-fly translation from x86 instructions to Itanium instructions, which results in slow execution of 32-bit code. Not a satisfactory solution.

It looked for a while as if a battle royal was developing between Intel and AMD, a fight to the death, with winner take all. The two companies had chosen incompatible paths to 64 bits, and consumers would choose the winner (remember Betamax vs VHS?). Whichever company won, consumers would be the eventual losers, as one company would likely establish a near monopoly, and innovation would slow and prices would rise.

The two companies were facing off in a showdown. Earlier this year, Intel blinked first. On February 17, Intel announced new chips (codenamed Nocona, Potomac and Prescott), based on IA-32 architecture with 64-bit extensions. In "Intel 64-bit extension technology FAQs", posted on the Intel website March 2, Intel answers questions consumers may have about the new chips. Question 9 asks "Is it possible to write software that will run on Intel's processors with 64-bit extension technology, and AMD's 64-bit capable processors?". The gist of the answer in the FAQs is "yes". Intel does caution that this applies to most cases only, and reminds us that software written to take advantage of Intel's new SSE3 instructions would not run on current AMD 64-bit processors.

This should be great news for consumers. It means that Intel and AMD will continue to compete in the home or small office and enthusiast markets, with processors executing 64-bit instruction sets that are compatible with each other, and with the x86 instruction set. Our current software should work fine with either line of chips, and we can upgrade to 64-bit software when we can afford to, with the option of changing hardware from one company to the other without being held captive by software investments in versions that will not run on chips from the other company. For those who must have performance at any cost (big companies, the government), there is the Itanium line. However, on the basis of price per unit performance, the IA-32 architecture with 64-bit extensions may continue to carry the day. CFD enthusiasts and enthusiasts of scientific computing in general can look forward to the benefits of 64-bit computing (principally the ability to address more than 4 GB of physical RAM with a single processor and OS) at reasonable prices set by the home consumer market.

I guess you have forgotten to talk about the G5 from Apple !!

Steve

Steve,

I was aware that Apple beat AMD to market by a couple of months by getting their 64-bit G5 out in September of last year. However, if you think in that vein, SGI and Sun and DEC had 64-bit processors on the market years ago. They just never captured a significant portion of the home consumer and enthusiast market. Apple is doing better these days, but their sales are still a tiny fraction of the market. Thanks for the reminder, though.