On 3/18/07, Lourens Veen <[EMAIL PROTECTED]> wrote:
> A pentium 4 use double frequency ALU (this permit to simulate 2 ALU). > Pentium 4 at 3 Ghz exist sine more than 4 years. 3 Ghz cpu imply 6 > Ghz ALU in the pentium 4. I doubt that that ALU is 2x2cm though, it's probably very small with a localised clock. The Cell chip would perhaps be a better example; it's supposed to go up to 5 GHz I think. But then, that's basically a bunch of loosely coupled DSPs together with a simple PPC core (which I don't think runs at full speed actually, but I'm not sure), so that's another kettle of fish. I do think there's work going on about multiple clock domains and clockless computing, but I don't know whether they are anywhere near production on that.
The biggest limit to chip performance is wire delay. That means that any significant sort of routing or interconnect is going to limit your performance. On the other hand, if you can lay out a circuit where the data flows from transistor to transistor, making the interconnects negligible, then you can make circuits that are incredibly fast. I think I read about some GaAs chips doing 100GHz. These are very specialized sorts of circuits, though. With Intel's ALU, they used some kind of differential signalling, and they laid out by hand, allowing them to achieve a 2x throughput. -- Timothy Normand Miller http://www.cse.ohio-state.edu/~millerti Favorite book: The Design of Everyday Things, Donald A. Norman, ISBN 0-465-06710-7 _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
