On Tuesday, Intel--which previously said it would tie only Rambus Inc.'s Direct Rambus DRAMs to the Pentium 4--confirmed plans to build a P4 chip set using mainstream PC133 memory.

The news came as a complete surprise to the industry and could be a setback for Rambus' efforts to establish its DRAM architecture as the leading memory for next-generation PCs. Sources said top-tier OEMs were notified Monday night. Intel publicly disclosed the information Tuesday afternoon, although the chip set has been the subject of rumors for many months.

"We have added the new chip set to the roadmap for the Pentium 4, an additional chip set supporting PC133 SDRAM," the Intel spokesman said on Tuesday. The spokesman added that he believes Direct Rambus memory remains Intel's primary memory interface for desktop chip sets.

Officials at Rambus Inc. in Mountain View, Calif., were pragmatic when asked for comment.

"In all of my positions within the industry, I've always known that Intel has always evaluated the performance of all different types of memory in order to evaluate RDRAM," said Avo Kanadjian, Rambus' vice president of worldwide marketing. "I'm confident when matched with Pentium 4, and a dual-channel RDRAM chip set, RDRAM will be superior."

According to sources, the PC133 chip set does not have an "official" name, and Intel has been close-lipped about its feature set.

An Intel spokesman in Santa Clara acknowledged that the chip set is a new addition to Intel's product portfolio.

Analysts, including Dean McCarron of Mercury Research, Scottsdale, Ariz., said they believe the chip set will be emerge as a volume solution for the desktop market in the second half of 2001.

"This was a exceedingly logical step if Willamette was going to reach the kind of volumes it was going to achieve," McCarron said.

The on-again off-again support for PC133 SDRAM has been one of the most frequently discussed subjects during the past 18 months. Intel floated the concept of supporting Direct RDRAM memory, then later committed the entire Pentium 4 platform to Direct Rambus. Intel introduced the Rambus-enabled Intel 820 chip set for the Pentium III, then slipped in the PC133-enabled Intel 815 chip set in the low-end PC space.

OEMs, in addition, have also reported that Intel is working on an improved I/O Connector Hub, or ICH, to support PC133 in the Willamette platform, although the Intel spokesman said that's not the case. Instead, Intel is designing a new chip set, he said.

Intel has also given signs it might be waffling. In June of 1999, for example, Intel chief executive Craig Barrett said that "if it happens that PC133 becomes a preferred choice, Intel has lots of options for creating new memory bus lines in chip sets."

Intel vice president Pat Gelsinger told attendees at the Intel Developer Forum in February that Intel had "no plans to support synchronous DRAM" in the Tehama chip set that will be matched with Willamette, leaving room for an additional PC133 chip set.

Kanadjian declined to directly answer the question of whether Rambus' legal stance would change regarding Intel. Rambus has successfully persuaded Hitachi and Toshiba that it owns fundamental rights to the DRAM interface, and now requiresthose companies to pay royalties.

Intel, among others, is preparing an antitrust defense against Rambus under the umbrella of a next-generation memory group, according to sources close to the discussions (see July 17 story).

"Our position has been and continues to be not to share customer-specific information on any of the licensing negotiations," Kanadjian said. "Clearly, our desire is to negotiate and settle amicably, and the settlements with Hitachi and Toshiba are proof of that."