Rambus speeds up its DRAM

The memory-chip designer is updating its technology at a critical time, as rivals have been helping to popularize the competing Double Data Rate SDRAM.

John G. Spooner Staff Writer, CNET News.com
John Spooner
covers the PC market, chips and automotive technology.
John G. Spooner
2 min read
Memory-chip designer Rambus will show off faster versions of its DRAM technology in San Francisco this week at the Intel Developer Forum, a confab for computer-hardware designers, the press and other tech mavens.

The new RDRAM flavor is called RIMM4200 and is an update of Rambus' RIMM technology--for Rambus inline memory module. It adds a second memory channel and faster new chips to increase the speed at which data moves from the module to other PC components.

The RIMM4200 incorporates two 2.1GB-per-second memory channels to transfer data at a combined rate of up to 4.2GB per second, Rambus said. The current Rambus RIMM, the 1600, uses only one channel and offers rates of 1.6GB per second--though many PCs use dual-channel configurations that pair modules to deliver rates of up to 3.2GB per second.

The RIMM4200 module also uses new, speedier RDRAM chips running at 1066MHz. The current Rambus RIMM uses 800MHz RDRAM chips. RIMMs are constructed by combining several chips on a circuit board.

The move by Rambus comes at a critical time for RDRAM. Though PC makers and Intel say RDRAM continues to offer the highest performance, efforts by Advanced Micro Devices and a new Intel 845 chipset for the Pentium 4 have helped popularize a rival technology known as Double Data Rate SDRAM.

DDR SDRAM, a faster version of standard Synchronous Dynamic RAM, is now available from all but a few PC makers, who generally pitch the technology as a middle-of-the-road offering between RDRAM and SDRAM. As a result, Rambus finds itself in the position of having to convince buyers to upgrade to RDRAM over DDR SDRAM.

Rambus' 4200 modules should be available starting in the second quarter of this year and, according to sources, will be part of a coming hardware upgrade for high-end, Pentium 4 desktop PCs, which Intel plans for the early summer.

At that time, Intel is expected to incorporate the new flavor of Rambus and bump the speed of its Pentium 4 front-side bus from 400MHz to 533MHz. The bus provides a data pathway from the memory to the processor. Increasing the speed to match the faster memory allows the PC to shuttle data more quickly between memory and the processor, speeding overall performance.

Samsung and other DRAM makers will manufacture the new RDRAM chips or RIMMs. Samsung will offer its own demonstration of the new memory at the Intel Developer Forum, the company said.

The 4200 modules are part of a Rambus plan, announced last year, to boost RDRAM from its current transfer rate of 1.6GB per second at 800MHz to 9.6GB per second at 1200MHz by 2005.

The extra RDRAM performance will be needed, as DDR SDRAM now runs at speeds of up to 333MHz and offers data rates of up to 2.7GB per second. But most PC makers offer the technology at 200MHz and 266MHz, where it offers data rates of 1.6GB and 2.1GB per second, respectively.