26 December 2002
I was going over some old press releases for an another article I'm doing, when I came across this one from S3 dated September 17th. It mentions a license agreement between S3 and Kentron for incorporating Quad Band Memory (QBM) technology into core logic chipsets.
This license marks the first time that PC based systems will be able to interface to high speed DDR533 and DDR667 modules featuring QBM technology. New systems using QBM enabled chipsets from VIA and S3 Graphics will combine the fastest speed memory in the industry with the fastest processor bus speeds and maintain backward compatibility with today's DDR modules.
S3 is not the only company to announce support for QBM. However, most of the intial announcements of QBM support were from earlier in the year. It's is now the end of 2002 and there is still no QBM products on the market.
So what is Quad Band Memory? Well, QBD attempts to address the memory subsytem bottleneck by using standard DDR memory and its associated 184-pin DIMM interface. They do this by taking two banks of DDR and delaying the second bank by 90 degress. By using advanced switching techniques, they are able to generate 4Bits/cycle versus the standard 2Bits/cycle.
The switch component is the key in QBMâ??s bit packing technique which provides twice the bandwidth of standard DDR devices. The QBM switch component also acts as an On / Off switch to turn off the QBM modules not in use in a system, thus reducing the capacitive load on the memory bus and allowing for greater system density. For a more indepth discussion of QBM, take a look at this pdf file.
Kentron claims that QBM offers superior price/performance ratio over upcoming technologies like DDR-II. But if that is the case, why isn't it being utilized already?