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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