Memory technology to evolve with DDR2

DRam (dynamic Ram) suppliers will start the transition to a new memory architecture this year which will allow chips to run...

DRam (dynamic Ram) suppliers will start the transition to a new memory architecture this year which will allow chips to run faster in gaming and multimedia PCs.

Nearly every PC sold today uses DDR (double data rate) SDRam (synchronous DRam) in one of four main speed grades.

PC3200 memory is the most commonly used memory in performance systems with an effective clock rate of 400MHz, although faster technology exists that has not been ratified by a standards body.

The DDR2 architecture allow memory chips to run faster and help boost server performance.

DDR2 memory improves the signal quality of data transmissions travelling within a PC, said Dean McCarron, principal analyst with Mercury Research.

Memory chips based on the older architecture could not run much faster than the existing speeds without suffering a marked decline in signal quality.

To boost memory speeds, chip designers effectively doubled the number of signals the memory chip could process using a technique called differential signalling, McCarron said.

They also added on-die termination, which allows the memory chip to absorb more "noise" created by signals as they travel through a system and, therefore, improve signal quality, he said.

Micron Technology, Samsung Electronics, Elpida Memory, Hynix Semiconductor and Infineon Technologies already ship DDR2 memory chips at 400MHz and 533MHz date rates.

PC users will not be able to plug in new memory modules to take advantage of the technology, because the modules will require new chipsets.

Intel's Grantsdale chipset will support DDR2 when it is launched in the second quarter, and Via Technologies and Silicon Integrated Systems are also expected to support DDR2 in forthcoming chipsets.

DDR2-400 is not expected to offer a large increase in performance compared with DDR400. The standard will really begin to shine with later versions that will run at 533MHz and 667MHz.

By 2005, DDR2 prices should be equivalent to DDR400 prices, paving the way for mass adoption.

While DDR SDRam has been the accepted memory standard for several years, other companies are also working on technologies that will help push the boundaries of performance.

Rambus announced a memory interface called XDR (extreme data rate). It allows for clock rates as high as 3.2GHz, said Rich Warmke, director of product marketing for Rambus.

XDR also uses differential signalling, but uses it throughout its entire architecture, whereas DDR2 uses the technique in only one aspect of its architecture, Warmke said.

Existing memory architectures use a technique called multidrop, where multiple memory modules are connected to a single wire. XDR switches to a point-to-point architecture, where each memory module communicates directly with the memory controller without having to share bandwidth with other modules.

Toshiba and Sony have licensed the XDR technology, which is expected to make its debut in consumer graphics and networking products. The technology should be ready for the PC market by 2006 2007.

Tom Krazit writes for IDG News Service

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