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IF YOU THINK AMD'S OPTERON AND INTEL'S NOCONA - OR MORE FORMALLY, "Xeon Processor with 800MHz System Bus" - are cut from the same 64-bit cloth, look closer. Yes, they're compatible at the instruction-set and register levels; they should be because they're both based on AMD'sx86-64 specification. But the total system architecture surrounding these chips - which includes pathways to other CPUs, memory, and peripherals - exhibits several differences that factor into buying decisions and developers' platform targeting.
At its core, Nocona is a NetBurst Xeon DP, a Pentium 4 equipped for dual-processor operation. It has 1MB of Level 2 cache and a top clock speed of 3.6CHz. All memory and I/O data, interrupts, interprocessor communication, and address requests flow over a fast shared bus with a maximum bandwidth of 6.4GBps. It's a highly evolved design, on the leading edge while remaining faithful to the legacy design principles that Intel is expected to maintain.
The 64-bit technology common...