Sun Microsystems, Inc.
Figure 2-7: Intel vs. Opteron Architectures
I/O Expansion Capability to High-Speed Industry Buses
The traditional Northbridge/Southbridge architecture is not intended to support more than two core-logic
elements. Adding additional high-speed functionality (such as Gigabit Ethernet, PCI-X, the InfiniBand
Architecture, or any combination thereof) would have to occur in one of three ways:
•The functionality would have to be attached to an existing bus interface such as the PCI bus. However, an
existing bus may not have sufficient bandwidth to support high-speed technologies, especially in instances
in which multiple buses or combinations of buses must be supported simultaneously.
•The functionality would have to be directly attached to the higher speed proprietary chip-to-chip interconnect
bus via a bridging device. However, the proprietary nature of this solution may limit the number of
components available from vendors, thus impacting cost and availability.
•The functionality would have to be integrated into one of the core logic components. This solution is the
least flexible, as a wide range of components would have to be created for each desired combination of
feature-set buses.
HyperTransport Technology, an industry standard, provides system designers a high-speed, daisy-chained
interconnect between system components. Specific components can be connected in a building-block fashion
to achieve a platform with specific feature-set and performance objectives.
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