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Fusion and Bobcat


New AMD CPU Designs Explained

AMD has unveiled details of its upcoming CPU designs, which include its first Fusion chips that combine a CPU and GPU on a single piece of silicon. Fusion is AMD's answer to Intel's current crop of Core i3 and Core i5 chips that offer both a CPU and GPU on a single package. However, instead of simply taking the two chips and plopping them on the same package, AMD is making them out of a single piece of silicon, which in theory offers many benefits in terms of performance, manufacturing costs, and power consumption.

This is a very similar tactic to that employed by AMD when it launched its first quad-core CPUs. While Intel was happy to simply bolt a couple of dual-cores together, AMD insisted on making a 'proper' quad-core design. This tactic didn't, however, work out as the relatively poor performance of its Phenom processors has shown. The company insists this latest crop of CPUs won't suffer the same fate, though.

Being as some of these new chips are more than just what we normally think of as a CPU, AMD has come up with a new name for them, which it hopes will catch on. Accelerated Processing Unit (APU) is the term in question and we actually rather like it, though we can certainly see a few people getting confused by it.

As well as new designs for its Fusion range, AMD also detailed its new performance CPU designs, which will be coming to servers and high-end users in early 2011 along with the Fusion chips. Both designs will be the first to use AMD's new 32nm Silicon On Insulator technology, down from AMD's current 45nm tech.

AMD Bobcat, Llano and Fusion

Bobcat is the name for AMD's new low power CPU core design. It's meant to rival Intel's Atom and CULV processors in terms of speed and power consumption thanks to its miniscule sub-1W power usage. Unlike Atom (and like CULV), it's an out-of-order design which means threads can be processed in a different order to when they were received, which is a considerably more efficient and responsive way of churning through calculations working (the analogy here is a caravan backing up traffic on a single carriageway road).

Atom doesn't use this method as the extra processing needed to work out what order to put the calculations adds a considerable amount of extra circuitry, which takes up space on the silicon and thus uses more power. AMD apparently has seen a way round this or feels it has found the right balance of speed and power saving.

So, in essence this is a 'proper' modern CPU. Indeed AMD points out these new designs will have 90 percent of the compute power of a current mainstream CPU, but will take up half the silicon area. Depending on what you define as mainstream this could result in chips that sit somewhere above the level of an Intel CULV or somewhere on or below an Atom. We suspect it will nestle somewhere between the two, which if the chips deliver on battery life as well is going to be a very nice middle ground.

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