An Overview of Quad Band Memory

tedgyz writes "AnandTech has a short article on a new memory technology from Via, called Quad Band Memory (QBM). Rather than using dual-channel DDR to increase bandwidth, they use phase-shifting inside the memory modules to accomplish the same goal. The end result is simpler (and presumably cheaper) motherboard designs that are backwards compatible with current DDR modules. The downside? It is currently only going to available in a P4 chipset that Intel has not authorized."

Comments

It's Kentron's invention

[HardCase]

You can see more about this on Kentron's web site. They developed the technology, then released it, royalty free, to manufacturers.

Given the memory manufacturers' resistance to DDR400 and the achingly slow progress that DDR2 is taking (the module standard isn't even final yet), this technology has a pretty good potential to reach production.

-h-

I dunno, these are gonna cost more.

[io333]

From the article:

*snip*

Here's where the difference between QBM and conventional modules comes into play; QBM modules will have a set of 8 registers (QBM-10) as well as a phase-locked loop (PLL). The purpose of the PLL is to take the incoming clock signal from the chipset and shift it by 90 degrees; this shifted signal is then fed to the second bank of the DIMM, while the first bank receives the unaltered clock directly from the chipset.

The 8 registers then switch between which bank gets to transfer data every clock; because of the 90 degree phase shift, there is a slight delay in transferring data from the second bank but both transfers actually end up happening within a single clock cycle. The end result is that you get two DDR transfers per clock, or 4 bits of data are sampled per clock thus doubling the throughput of DDR (hence the name Quad Band Memory).

*snip*

QBM modules will obviously be more expensive than regular DDR modules, the question of how much remains to be answered however.

Let's see, one PLL... damn, I don't know if I can afford the extra six cents!

(That extra six cents though doesn't detract from fact that this idea is just pure genius... with about 30,000 folks slapping their forheads for not thinking of it first!)

why is that a downside?

[geekd]

The downside? It is currently only going to available in a P4 chipset that Intel has not authorized."

Why is this a downside? Why should I give a rat's ass what Intel "authorizes".

Intel sure as hell didn't authorize my Athlon on it's Abit mobo with a Via chipset.

Is there an actual downside to not getting Intel's blessing (downside for consumers, not the company making the mobo)?

Terrestrial cosmic ray intensities

[richard-parker]

Radiation(white noise) was always a problem with RAM, much more so at higher elevations(Colorado gets about 100x more ram errors than sealevel does, necessitating ECC ram)

Actually, the increased RAM failure rate due to the greater cosmic ray intensities at higher altitudes isn't as bad as you describe.

For example, the expected soft-fail rate of a computer memory system in Denver, Colorado is about 4 times greater than the rate expected at a city it sea level (such as New York City). Even in Leadville, Colorado (which is located at 10,151 feet) the expected failure rate is only about 13 times greater than in NYC. No location in Colorado even approaches 100x.

For more information, see the following paper:

J. F. Ziegler, "Terrestrial cosmic ray intensities", IBM Journal of Research and Development, Vol. 42, No. 1, 1998.

It can be found online here.