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.
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.
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.
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.
switch component is the key in QBMís 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
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?
QBM is not dead. In fact, they recently announced support
Technologies has announced that its family of high performance
QBM memory modules will support the DDRI-400 DRAM devices
expected to become mainstream in the 2nd half of 2003.
while DRAM manufacturers like Samsung, Micron, Hynix and Elpida
focus their resources on improving bandwidth at the device level,
Kentronís approach improves speed and density on the module
or "platform" level using standard, "off-the-shelf" DRAM devices.
By combining the low cost, QBM switch component and DDRI-400
devices, Kentron and its partners will deliver QBM800 modules
that match the 800MHz front side bus of new system processors
(CPUs) expected to be available in the 2nd half of 2003. The
QBM800 modules will operate up to 6.4 GB/sec (single-channel)
and 12.8 GB/sec (dual-channel) and will be positioned as the
lowest cost and highest performance memory modules in the
industry. Kentron and its channel partners will be introducing
QBM533 (4.2 GB/sec) modules using DDRI-266 memory devices
in Q1 of 2003.
products will be able to take advantage of QDM? It
appears that the new P4X800 chipsets from VIA
Technologies, Inc. may be the first.
QBM533 modules combined with the VIA P4X800 memory controllers
will match the fast 533MHz front side bus of CPUs and provide
the highest performance single channel solution in the system
marketplace. As the CPUs move to the faster 667MHz and 800MHz
front side bus, Kentron will be providing QBM based solutions
to meet those speeds using available low cost DDRI-333 and
DDRI-400 memory devices.
Modules based on DDRI-400 devices won't be available until the
second half of 2003. By that time, DDR-II may be gaining popularity.
Hopefully, QDM won't go down in history as a good idea, that
was too late too market.