A new memory technology due in PC systems this autumn promises better performance for desktops and workstations at little extra cost. But Quad Band Memory (QBM) is just one of several high-speed memory technologies competing to be the next industry standard, meaning that large firms may defer buying such technologies until a clear winner has emerged.
QBM is an evolution of the existing Double Data Rate (DDR) memory standard, but it offers twice the data throughput. Because QBM can make use of existing memory components, it can match the performance of other high-speed memory technologies at much lower cost, according to QBM inventor Kentron Technologies.
"We started with the recognition that the need for speed wasn't being served by the memory manufacturers, and that there was a large performance gap between the front-side bus speed [of processors] and memory bandwidth," said Kentron chief executive Bob Goodman. The firm came up with a solution that uses existing technology and also fits into the same motherboard sockets as current Dual In-line Memory Modules (Dimms), he added.
QBM works by squeezing two separate DDR memory banks onto each QBM module. A controller on the module interleaves reads and writes to the two banks in such a way that four memory accesses are made per clock cycle, compared with two per cycle for standard DDR and one for the older SDRAM memories.
Kentron has formed the QBM Alliance to promote the technology. It includes memory, motherboard and chipset firms, such as VIA Technologies, Acer Labs, Silicon Integrated Systems, and ST Microelectronics. Kentron has also submitted the QBM specifications to the Jedec electronics standards body for approval, and said it will license the technology royalty-free.
VIA said it will support QBM modules in its PT880 chipset for Pentium 4 desktops, due to ship in September. This chipset paired with a single QBM 533 module will be a match for a Pentium 4 processor with a 533MHz front-side bus, according to VIA. Current desktop chipsets need a minimum of two DDR modules arranged in dual memory channels to provide as much data throughput. Using two QBM modules will offer even higher throughput.
Although each QBM 533 module has two sets of DDR chips, these are comparable in cost if not cheaper than the DDR 333 and DDR 400 modules in current desktops, according to Kentron, because they use the older DDR 266 chips that are cheap to produce. QBM modules are also planned using DDR 400 parts to support newer Pentium 4 chips with an 800MHz bus.
But QBM is not the only high-speed memory technology in the pipeline. It faces competition from the next generation of DDR memory, DDR II, as well as faster versions of Rambus RDRAM and more exotic newcomers such as XDR.
Ultimately, however, QBM's adoption in enterprise desktops is likely to depend on whether Intel supports it in a future motherboard product.
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