Rambus unveils 6.4GBps, 3.2GHz next-gen RDRAM

Yellowstone debuts

Rambus yesterday introduced Yellowstone, its next-generation memory technology, designed to accelerate data transfer rates of up to 6.4GBps between processors and RAM.

Yellowstone comprises two key components. The first, Octal Data Rate, essentially doubles Rambus memory's data rate. Using a phase-locked loop - which sounds like something out of Doctor Who, but we assume these Rambus engineers know what they're up to - the technology gives RDRAM an effective clock frequency of 3.2GHz.

The chip's core 400MHz frequency is boosted to 1.6GHz, then doubled to 3.2GHz by the PLL, which allows data to be read on the falling and rising curves of the voltage, much like the way current DDR SDRAM chips operate.

Rambus' roadmap calls for that to be doubled again, to 6.4GHz, though the company has yet to announce a timeframe for that shift.

In addition, Yellowstone uses differential signalling to reduce to 200mV the extent to which the voltage rises and falls as a signal is transmitted. Current RDRAM chips operate with a voltage amplitude of 800mV; other DRAM parts operate at 3300mV (3.3V). The lower the amplitude, the quicker a falling voltage can be raised again, and the faster the signal can be physically transmitted. That has a knock-on improvement on the chip's data throughput rate.

Rambus said Yellowstone will initially made its presence felt in the video game arena, where ever greater memory bandwidth is required to move complex graphics data around the system. However, company president David Mooring said the technology could one day find its way into PCs - though not, we suspect, given Intel's current downer on the company and its technology.

Cost too will play a part. A dual-channel memory system based on 266MHz DDR SDRAM would give 4.2GBps bandwidth, which is both plenty for current and next-generation PC processors - and considerably cheaper than the Rambus product is likely to be.

As yet, Rambus has announced no Yellowstone licensees. ®