Two billion-transistor beasts: POWER7 and Niagara 3

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In years past, an ISSCC presentation on a new processor would consist of detailed discussion of the chip's microarchitecture (pipeline, instruction fetch and decode, execution units, etc.), along with at least one shot of a floorplan that marked out the location of major functional blocks (the decoder, the floating-point unit, the load-store unit, etc.). This year's ISSCC is well into the many-core era, though, and with single-chip core counts ranging from six to 16, the only elements you're likely to see in a floorplan like the two below are cores, interfaces, and switches. Most of the discussion focuses on power-related arcana, but most folks are interested in the chips themselves.

In this short article, I'll walk you through the floorplan of two chips with similar transistor counts—the Sun's Niagara 3 and IBM's POWER7. Most CPU geeks will already know a lot of the information I'll give below, but many readers will appreciate having it all together in one place.

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