DDR tugs tiger's tail -- Rambus rival will broaden memory-IC options
Andrew MacLellan
Silicon Valley- Despite Intel Corp.'s well-orchestrated campaign to guide OEMs toward a single next-generation memory architecture, a group of component suppliers last week made it clear that Direct Rambus DRAM won't be the only debutante at next year's coming-out party.
Forging a path parallel to the one blazed by Intel and its architectural partner, Rambus Inc., nearly a dozen DRAM vendors said they will ramp double-data-rate SDRAM into volume production in 1999, giving OEMs a competitive high-bandwidth memory alternative.
The manufacturers, all of which also happen to be Direct RDRAM licensees, will bring DDR into volume production at about the same time that Rambus memory is scheduled to penetrate the upper reaches of the PC market.
"This was an effort to prove to people that the DRAM industry can get together and agree on a common spec," said Jim Sogas, director of DRAM marketing at Hitachi Semiconductor (America) Inc., Brisbane, Calif. "We expect DDR to go from near-invisible to the forefront of people's thinking in the next six months or so."
Such a united front is uncommon in the competitive DRAM industry, and is all the more remarkable because processor giant Intel has so far refused to design support for DDR into its chipset roadmap.
"Intel is going to do what they're going to do," Sogas said. "But I don't think they can ignore what the rest of the industry is doing."
Although Hitachi said 2.1-Gbyte/s DDR bandwidth is possible now, Rambus said the claim is premature and will be bettered by subsequent versions of Direct RDRAM.
"Historically, we've shown a performance increase of 15% to 20% on an annual basis," said Subodh Toprani, vice president and general manager of Rambus' logic products division, Mountain View, Calif. "I can't say that we'll continue at that pace indefinitely, but we're not going to remain static."
Hitachi and other suppliers said they expect DDR to succeed first in high-end server applications, where longer design cycles evoke a more cautious technology-upgrade track. Because DDR is a close cousin to existing EDO DRAM and PC-100 SDRAM, it presents fewer technical challenges, according to suppliers.
"We think DDR will find a welcome market in the server-applications space," said Lane Mason, director of graphics/memory product strategy for IBM Microelectronics in Burlington, Vt. "That includes PC servers driven by Intel, but also goes up to high-end servers from HP, IBM, and Compaq."
So far, server divisions within both IBM and Mountain View-based Silicon Graphics Inc. have endorsed DDR in future high-end platforms.
"After thorough consideration, we believe DDR offers better bandwidth per module and lower latency than [Direct] RDRAM," said Richard Bahr, vice president of SGI's Engineering, Server, and Supercomputing business unit, in a statement issued last week. "Moreover, DDR offers lower intrinsic costs both in the DRAM itself and in the ease of integration with our current server architecture."
Toprani noted that Compaq Computer Corp. has already committed its server line to Direct RDRAM. He said any support for DDR among high-end computer companies is rash and stems from early commitments to the technology. "My belief is that subsequent to this product cycle, they will come back to Rambus because it has better performance and better price," he said.
Other DRAM suppliers, however, maintain that DDR will also compete effectively in the mainstream PC arena, a claim that could bring DDR into more immediate and widespread competition with Direct RDRAM.
"We're not attempting to stop what [Rambus proponents] are doing," Sogas said. "What we're hoping to accomplish is to let people know there are cost-effective alternatives. We're not trying to say that Rambus isn't good, but our target is definitely to penetrate the PC. We think we'll achieve that, and may the best DRAM win."
The coexistence of several DRAM variants is nothing new in a market that currently supports fast-page-mode and EDO DRAM, as well as PC-66, PC-100, and PC-133 SDRAM. The emergence of Rambus and DDR is different because both technologies will be introduced at roughly the same time, whereas previous DRAM interfaces were rolled out in consecutive order.
"There's a possibility that just as EDO forestalled the advent of SDRAM, a higher-frequency SDRAM could delay the transition to Rambus," said Jim Handy, an analyst at Dataquest Inc., San Jose. "The chances of this happening are becoming more remote, but there is still a possibility."
What's likely to happen over the next six months, observers said, is a pitched battle of performance metrics, with supporters from each camp poking holes in the claims of the other. And there is evidence that this is already happening.
While Rambus has consistently touted the 1.6-Gbyte/s bandwidth of its 8-bit-wide Direct RDRAM architecture as industry-leading, DDR proponents now claim they can deliver up to 2.1 Gbytes/s using a standard 133-MHz SDRAM DIMM running on a 64-bit-wide bus.
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The DDR SDRAM Story
Supporters:
Fujitsu Ltd., Hitachi Ltd., Hyundai Electronics Industries Co. Ltd., IBM Microelectronics, LG Semicon Co. Ltd., Micron Technology Inc., Mitsubishi Electric Corp., NEC Corp., Samsung Electronics Co. Ltd., Siemens Components, Toshiba Corp.
Volume production:
Slated for 1999
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