HOW PROCESSER WORKS

HOW PROCESSER WORKSIf you've been reading Ars for a while then you know that we don't normally do generalized overview articles. Most of our articles deal with specific technologies and products. However, the success of my recent article on bandwidth and latency, which was in fact a general overview, got me thinking that perhaps the time was right to do an overview of a topic that I write on quite often: microprocessor technology. This article, which is the first in a series, is aimed at providing the reader with the kind of background that he or she needs to understand the CPU technology coverage on Ars and on other sites. And with Itanium2, Yamhill, AMD's Hammer, and other new chips on the horizon, there's quite a bit of such coverage coming up. Here's a quote from the article that should give you a taste for the level at which it's written.Since the numbers must first be fetched from storage before they can be added, we want our storage space to be as fast as possible so that the operation can be carried out quickly. Since the ALU is the part of the processor that does the actual addition, we'd like to place the storage as close to it as possible so that the operands can be read almost instantaneously. However, practical considerations, such as a modern CPU's limited die space, constrain the size of the storage area that we can stick next to the ALU. This means that in real life, most computers have a relatively small number of very fast storage locations attached to the ALU. These storage locations are called registers, and the first x86 computers only had 8 of them to work with. These registers store only a small subset of the data that the computer is currently working with.Although the article is fairly basic, I suspect that more advanced readers will also benefit from it. I know that it was quite helpful for me to go back and think about this material at a more abstract, conceptual level. In writing this article, I sort of felt like I was building large boxes in which to put all of the things I've learned over the yea