In lifting the lid off the "10H" architecture that will power its upcoming quad-core processors, Advanced Micro Devices is challenging Intel once again in the battle for processor supremacy.

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To understand the competition, you must untangle the race to market from the debate over whose architecture is better. Intel is clearly ahead in the market. It already offers several quad-core desktop processors, as part of its Core 2 Quad and Core 2 Extreme lines. On the server side, Intel is shipping no fewer than nine quad-core Xeon chips.

Intel's laundry list of planned intros includes two quads based on its latest 45-nanometer chip technology: Yorkfield for desktops and Harpertown for servers. Both are due in the second half of the year.

		Quad Core Unfolds
		Desktop	Server
	I N T E L	Core 2 Extreme (QX6800, QX6700)* shipping	Xeon Clovertown (E5300, X3200, LV5300)* shipping
		Core 2 Quad (Q6600)* shipping	Harpertown 45-nm 2nd half '07
		Yorkfield 45-nm 2nd half '07
	A M D	Quad FX Platform (2 dual cores Athlon64 FX-70, 72, 74) shipping	Barcelona 65-nm Opteron quad 2nd half '07
		Phenom 65-nm native quad processor 2nd half '07	Shanghai 45-nm Opteron quad 2008
	*Selected models come in quad core as indicated

AMD, behind in the race to ship quads, wants to shift the discussion to which has the better processor. With Phenom, the just-announced name for the desktop quads previously code-named Agena, and with Barcelona, the upcoming quad-core version of the Opteron server chip, AMD thinks it does. Barcelona is expected to ship sometime this summer; Phenom will follow later this year.

AMD never hesitates to point out that its initial quad-core processors are fresh, from-the-ground-up designs. No other manufacturer has native quad cores, says Ian McNaughton, AMD's FX product manager. "Our competitors have dual, dual cores."

That dig refers to Intel's first-generation quads, which place two dual-core processors side by side in a multichip module--a design that AMD claims is less elegant than its "native" quad core.

Intel doesn't think so. As CEO Paul Otellini said in September: "The initial ones are multichip, but so what? You guys are misreading the market if you think people care what's in the package."

Judging from past history, PC users are more likely to care about performance than design issues. When dual cores debuted in 2005, a similar marketing battle occurred. AMD touted its Athlon 64 X2s as "true" dual cores compared with Intel's bolted-together 800-series Pentium Ds. However, the dual-core duel became, and remains, a performance battle. AMD was widely perceived to have had an initial lead. But Intel recovered the advantage when it introduced its Core 2 Duo line last year.

When Phenom and Barcelona ship later this year, AMD is hoping the new 10h architecture will help it do some performance leapfrogging of its own. The architecture incorporates enhancements aimed at speeding performance, including advanced instructions, improved floating-point execution units, and faster data transfer between floating-point and general-purpose registers. AMD also added optimization to make its hardware- based virtualization run faster.

Much of the elegance of AMD's approach is in the way it handles input/output to external devices and interprocessor communications. Its proprietary HyperTransport interface provides a more direct connection to the outside world than conventional methods. With 10h, the new-generation of HyperTransport3 debuts, boosting the bandwidth of the link by 86%.

AMD has said its quad-core Opteron would be fabricated in 65-nm CMOS technology. Intel will ship 45-nm quad cores later this year. Smaller is better in chip making because its enables lower power operation. It also lets the vendor get higher yields, by placing more processors on each of the 300-mm wafers on which they're made.

AMD is emphasizing that Phenom will support dual-socket motherboards. This will let two chips, each with four processors, be placed in the same system, for eight cores overall. Barcelona will allow similar multisocket configurations (including a four-socket NUMA design at the very high end), as will Intel's offerings. Clearly, the race to four cores will soon become part of the race to eight.