rmbs news
Date: 04/10 00:13 EST
Rambus preps 700-MHz DRDRAM
Apr. 09, 1999 (Electronic Buyers News - CMP via COMTEX) -- Rambus Inc.
has added a 700-MHz speed grade to its Direct Rambus DRAM specification
in a move to help DRAM suppliers improve early yields of the device,
EBN has learned.
Though they refused to discuss specific yields, some DRAM makers
privately confirmed that a significant portion of the industry has been
hard-pressed to achieve the 800-MHz frequency defined in the original
spec. Rather than their having to struggle with poor output, it is now
hoped that suppliers will sell large volumes of the 700-MHz Direct
RDRAM devices while they continue to refine their manufacturing
processes.
Contacted last week, Hitachi Semiconductor (America) Inc., San Jose,
said its 0.18- micron lines are producing 800-MHz chips. "I suspect
companies that don't have 0.18-micron processing may have trouble
getting adequate yields of 800-MHz chips and may need the lower speed
specification," said Bob Fusco, Hitachi's DRAM product marketing
manager.
The decision to tinker with the specification just six months before
the technology's volume introduction has drawn a variety of responses
from industry pundits. Rambus proponents point to the change as an
effort to accommodate customers, while detractors say the 11th-hour
alteration is another sign that the platform may be unstable.
In an interview last week, a spokesman for Rambus' design partner,
Intel Corp., confirmed that a 700-MHz speed has been inserted between
the original 600- and 800-MHz Direct RDRAM versions.
At Rambus, Mountain View, Calif., logic products division vice
president and general manager Subodh Toprani said the new spec was
adopted "on the recommendation of Intel and our DRAM licensees. They
felt it would be an advantage to them and give them greater flexibility
in the market."
Analyst Robert Merritt of Semico Research Corp., Phoenix, said the
700-MHz speed will yield a lesser 1.4-Gbyte/s throughput, compared with
the 1.6-Gbyte/s bandwidth of 800-MHz Direct RDRAM. While the addition
represents no major change to the Rambus architecture, he said, the
last-minute addition could create more uncertainty for the memory chip,
which has already been delayed until late in the third quarter.
Suppliers said the change resulted from stricter testing guidelines
recently introduced by Intel, changes that are taxing the ability of
new test equipment to stay within narrow timing parameters.
"Yields of 800 MHz are not significant," said one vendor. "The test
equipment has limitations. It hasn't evolved far enough."
Most DRAM vendors contacted had yet to receive clearance from Intel
to discuss the new speed grade. But Will Mulhern, product marketing
manager for advanced DRAMs at NEC Electronics Inc., Santa Clara,
Calif., said that in theoretical terms, the inclusion of a 700-MHz
speed grade would tend to send the industry two messages: that 800-MHz
yields are generally low, and that the 600-MHz down-bin is perceived as
too slow by OEMs.
"In general, the only reason you introduce a new speed grade is to
improve the yields for vendors," Mulhern said.
According to Toprani, the changed spec proves Rambus' commitment to
flexibility, and a third speed option will only broaden the base of
applications for the next-generation memory chip. The Intel spokesman
said the companies were simply responding to market demand.
Whatever assurances Intel and Rambus may offer, the Direct RDRAM
picture has become increasingly clouded. In February, after Intel
reported a delay for its Rambus-enabled Camino chipset and certain
peripheral devices, several DRAM companies said the 800-MHz speed would
be difficult to attain without a switch to 0.21- or 0.18-micron
processing-an expensive leading-edge geometry.
More recently, some DRAM makers said they'd received notice of a flaw
in the Direct RDRAM design that causes data to be misread to the bit
register. As previously reported, the DRAM vendors said the bug has
triggered an engineering change order that could require a new silicon
mask set.
Toprani confirmed that an engineering change was issued, but he
claimed "it's a non-issue for present-generation Direct Rambus DRAMs.
It's a change that can be implemented when manufacturers move to the
256-Mbit [Direct RDRAM] generation.
Both Rambus and Intel stressed that any changes to date have had no
effect on Direct RDRAM's revised September introduction date.
-0-
By: Jack Robertson
Copyright 1999 CMP Media Inc.
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