SANTA CLARA, Calif. -- Intel Corp. here is bringing focus to its shifting chip set and memory roadmap by confirming that it will "investigate" the use of double-data-rate SDRAM to support its upcoming mainstream Pentium 4 microprocessor.

In addition to turning to independent chip set makers to supply itwith DDR-enabled core-logic controllers, Intel has acknowledged for the first time that it "would investigate developing its own DDR chip set" for Pentium 4. The word followed an announcement earlier this week that the company will make a PC133 SDRAM chip set to support its P4 platform -- in addition to its original plan to support the next-generation processor with Direct Rambus DRAM.

Sources noted, however, that Intel's choice of PC133 leaves a gap between processor and memory performance, and would likely see the company quickly upgrade the core-logic interface to accept DDR SDRAM. Such a move would not only maximize the data throughput of the P4, but would parallel plans by Advanced Micro Devices Inc., which will field a DDR chip set later this year to boost the performance of its Athlon processor.

Sources familiar with Intel's roadmap said both Intel's PC133 and DDR SDRAM-enabled chip sets could debut in the second half of 2001, at about the same time the mainstream P4 for desktop PCs is launched. An earlier high-end version of the processor slated for release in the fourth quarter of this year is expected to only work with Direct RDRAM, sources said.

An Intel spokesman declined to comment on unannounced products or discuss the firm's DDR plans relative to the P4, other than to reiterate that the company is looking into the issue.

Many observers questioned why Intel would even consider a single-data-rate PC133 chip set for its next high-performance processor. Nathan Brookwood, an analyst at InSight64, Saratoga, Calif., said a PC133 chip set has a data rate of 1-Gbyte/s, which leaves the 3.2-Gbyte/s dual channel Pentium 4 starved for data. "A PC133 chip set simply doesn't make much sense for Pentium 4," he said.

Brookwood added that Intel's confirmation that it will build a PC133 chip set for the P4 is "a smoke screen" designed to cover the company's intention to develop a DDR-enabled controller for the processor.

The Intel spokesman defended the company's choice of a PC133/P4 matchup, claiming that not all desktop applications will need the dual-channel processor's full 3.2-Gbyte/s data rate.

Brookwood said the initial high-performance Pentium 4 being launched late this year makes a better case for Direct RDRAM. "The dual channel Direct RDRAM Tehama chip set with 3.2-Gbyte/s data rate is a perfect match for Pentium 4," he said. "The question is how soon affordable Direct RDRAM in sufficient supply will be available for a much broader Pentium 4 market."

As it readies the mainstream desktop P4, Intel is also said to be looking to third-party suppliers for DDR chip sets for both the high-end and mainstream desktop versions of the processor.

Via Technologies Inc., Taipei, Taiwan, for example, has included a DDR-enabled chip set in its roadmap to support the P4 next spring. Via's product marketing manager, Eric Chang, said last week that the company will ship a DDR chip set for Pentium 4 with or without an Intel license.

Despite Intel's long insistance that the P4 would be a Rambus-only part, companies like Via are looking to cash in by providing an insurance policy should Rambus memory have trouble ramping into the market. Bob Merritt, an analyst for Semico Research Corp., based in Redwood City, Calif., said top-end 800-MHz Direct RDRAM chips will still be in short supply in the fourth quarter and will cost more than twice that of an SDRAM of equivalent density.

"This may be enough to support the initial niche market of very high performance Pentium 4s, where customers may be more willing to pay premium memory prices," Merritt said. "But unless Direct Rambus prices come down sharply in the fourth quarter this year or early next year, Intel may be unable to transition Pentium 4 as quickly as it wants to the mainstream PC market against AMD's Athlon."