AMD relaunches LDT as HyperTransport

Targets broader markets than PCs and servers

AMD has renamed its Lightning Data Transport (LDT) technology HyperTransport and, as predicted, plans to create a consortium of supporter companies to drive the adoption of the technology and its establishment as a standard.

HyperTransport is AMD's new core I/O bus, providing a high speed, high bandwidth connection between a system's Northbridge and multiple, parallel I/O buses via an array of Southbridge chips. That allows compatibility with existing I/O and add-in systems, such as PCI, since they can be added to as system as just one more module on the HyperTransport bus.

Other, newer transport technologies can also be supported, thanks to this modular approach - just hook up another HT bridge to the chain. AMD claims that up to 32 bridges can be daisy-chained together, irrespective of their own bandwidth and speed specifications.

The bus also doubles up as a multiprocessing bus, connecting each processor's Northbridge to all the other processors' Northbridge chips. That's essentially a NUMA configuration, giving each CPU its own local memory, connected via its Northbridge, and access to other processors' RAM banks.

AMD reckons the technology will provide up to 6.4GBps of internal data throughput, rather better than today's typical interconnect bandwidths of 266MBps.

Chimpzilla developed LDT to allow its Athlon CPU to be used in multi-processor server environments, but the change of name to HyperTransport reflects the technology's applicability to other environments, many of them highly lucrative embedded applications. Along with the name change, AMD announced Sun, Broadcom, Cisco and Nvidia as its initial band of supporters.

A canny bit of PR, that. Each company represents specific sectors AMD wants to target HyperTransport at: servers; broadband networking; routers and comms products; and graphics, SoCs, North- and Southbridge parts, respectively.

The supporters are also key players within those sectors, which AMD hopes will pull in their competitors. Indeed, Nvidia's arch-rival, ATI, quickly leapt onto the bandwagon and declared its support for HyperTransport soon after the AMD announcement.

Of all these companies, only Nvidia has been linked to shipping product - almost certainly its Xbox chipset, and the PC-oriented versions of it that it's hoping to sell to. Nvidia's decision to license the technology slipped out last month at the Platform Conference in San Jose. Then, an AMD spokesman said ten companies, including Nvidia, had licensed LDT, and 20-30 others were evaluating it.

That may be why AMD isn't launching its HyperTransport Consortium just yet, preferring instead to suggest it as something it plans to do (though when the launch will take place, it didn't say). ®

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