John,
This article outlines VCM DRAM and the NEC/Nintendo connection- As I mentioned before, NEC "probably' was the reason RMBS secured the Nintendo 64 business to begin with and will probably be the reason if they lose the relationship- seems as if NEC has the stronger relationship with Nintendo, not RMBS, JMO.
MileHigh
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September 14, 1998, Issue: 1025
Section: News
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Vendors adopt NEC latency-reducing scheme -- Virtual channel DRAM gears to duel Rambus
David Lammers
Santa Clara, Calif. - The virtual channel memory, an NEC Corp. innovation that boosts DRAM performance by reducing latency, is picking up momentum among DRAM manufacturers. Several vendors are considering pairing the VCM core to a fast memory interface, in a move that would pose a challenge to Direct Rambus DRAMs in both high-end computers and low-end consumer products.
Siemens Corp. will announce this week that it will begin sampling a VCM 64-Mbit DRAM in the fourth quarter, with mass production starting in 1999, said Jan du Preez, vice president of memory products at Siemens' U.S. subsidiary. Other companies-including Micron Technology (Boise, Idaho), Hyundai/LG Semicon (Seoul, South Korea) and Samsung Electronics (Seoul)-are considering VCM-enhanced DRAMs, sources said.
Further, the 128-Mbit SLDRAM being developed by the SLDRAM Inc. Consortium (formerly Synclink) will offer VCM as an option, said consortium president Farhad Tabrizi.
An NEC spokes-man in Tokyo said he expects NEC to announce in coming weeks that one or more companies plan to support VCM. "We're in negotiations with several different companies, some pretty important companies, but we can't say who they are," he said. Another NEC spokesman denied the company is in talks with Micron and Samsung about using VCM.
Nintendo Ltd. (Kyoto, Japan)-which tapped NEC to provide the chip set for the successful Nintendo 64 game platform-is investigating a VCM-enhanced SDRAM solution for its next-generation game machine, though no decision has been made yet, said Peter Wolff, Asian electronics analyst at Barings Securities, who also reported Micron and Samsung are in discussions to use VCM. Nintendo 64 helped establish Rambus as a viable DRAM alternative.
artX (Palo Alto, Calif.), a startup formed by a group of engineers who left MIPS Technologies, is working with Nintendo on its next-generation machine. Asked whether Nintendo is interested in VCM, a source at artX said, "I can't comment, other than to say that artX and Nintendo are evaluating technology for a next-generation Nintendo product."
Questions of performance
It is not clear yet how far the DRAM manufacturers can improve performance simply by adding VCM (see Nov. 17, page 1). Tabrizi said several systems companies encouraged the SLDRAM group to pursue VCM technology as part of the standard. "We did a lot of simulations and believe that VC offers some benefit at a very small die-size penalty. The SLDRAM specification is flexible enough that we can make one pin-the ready pin-available to controllers that support the VC approach," Tabrizi said.
Gene Cloud, a former Micron Technology marketing manager who now teaches at Boise State University, said the VCM approach not only reduces latency but also cuts power consumption by keeping fewer banks open at the same time. Another source close to Micron said the company believes SLDRAMs combined with VCM would make a good alternative for second-generation Merced server designs.
Essentially, VCM aims to boost DRAM performance through improvements made to the DRAM core itself. Conventional DRAMs experience multiclock delays whenever a new page of the memory is addressed, because of the time it takes to precharge bit lines and transfer information from the memory cells through the sense amps to the I/O. Vendors have tried to counteract that effect by dividing the DRAM into multiple banks and thereby increasing the likelihood that a new memory reference will be in an already active bank.
VCM, on the other hand, battles precharge latency by allowing memory masters to open and control virtual channels-separate interface blocks, each with its own SRAM page buffer, that work to filter out page misses. Different system tasks can be assigned their own virtual channels. When one of the tasks accesses its assigned channel, it will find the SRAM page buffer still intact from its last operation and unaffected by the reads and writes from other sources.
The approach, developed by Jeffrey Lee, an engineering manager at NEC Electronics (Santa Clara), recently was approved as a Jedec standard. Companies can employ the VCM technology without paying license fees.
Last month, ARM Ltd. (Cambridge, England) announced that it is working with NEC to develop a memory controller for the latter's 64-Mbit VC SDRAM, now in production.
Siemens will provide a second source to the NEC product, said du Preez. "There are many companies in the workstation and server sectors that are looking at VCM DRAMs seriously. This provides a 25 percent improvement in the latency, and the cost adder is insignificant."
Siemens has created a VC SDRAM mask set. The cost of the set and the additional on-board logic is not that high, du Preez said. Pricing will depend on volume demand. The Siemens product will be packaged in a standard 54-pin TSOP.
Longer term, the combination of VCM and the packet-based SL-DRAM could provide an alternative to the Rambus memories. Cloud said SLDRAM strategy is to use VCM to get established at the high end, in servers and workstations, as well as in such low-end products as games consoles.
Steve Przybylski, principal analyst at the Verdande Group, noted that Rambus got an early boost when Nintendo, working with NEC as its principal chip supplier, opted to use the Rambus channel in the Nintendo 64 machine. But even if Rambus is not selected for the next-generation machine or the follow-on to that generation, Przybylski said, the memory architecture may be sufficiently pervasive on the desktop by that time to weather the loss of the game platform.
The virtual-channel approach improves a DRAM's performance, Przybylski said, but doesn't "improve it enough" to displace the Direct RDRAM in the mainstream computer market. Intel Corp., which initially was attracted to Rambus for technical reasons, now has business and market reasons to ensure that the RDRAM becomes the mainstream memory, he said.
But Przybylski added that the design forthcoming from the SLDRAM consortium, if enhanced by virtual-memory technology, "improves the balance of power" against the Rambus consortium.
Tabrizi said an SLDRAM designed by Micron is now sampling. The 64-Mbit SLDRAM, designed by Mosaid Inc. (Kanata, Ontario, Canada) and developed by the SLDRAM group, may be shown at Comdex/Fall.
Though system companies are eager to get their hands on VC SLDRAMs, 128-Mbit or 256-Mbit densities are required on modules. The 128-Mbit SLDRAMs will be ready for sampling by the first half of 1999 and in production by the second half.
Peter Gillingham, director of business development at Mosaid, spoke in support of VCM. "It is an option that can reduce the latency on a cache miss from 50 to 60 nanoseconds down to about 15 ns."-Anthony Cataldo contributed to this report.
Copyright ® 1998 CMP Media Inc.
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