Originally posted by: Pete
You could start by reading the introductory G70 and R520 p/reviews, the ones which go into the marketing material and describe the various features using ATI's and NV's respective PR pics. The more articles you read, the more likely one of those poor, overworked and underpaid reviewers will spell it out to you intelligibly. My first stops would be Beyond3D, BeHardware, TechReport, Anandtech, XbitLabs, Digit-Life (all .com), and Hexus.net. 3DCenter.org is also one of the more detail-oriented sites, but it's German; English translations only follow later, and only sometimes. TR and AT may explain things at a higher level and therefore be easier to understand (TR's Scott [aka Damage] in particular is a wicked good writer, eh); the rest may not be written as approachably or edited as well, but they really get into the nitty gritty, especially with custom programs to explore a GPU's details. These programs are often community-supplied, in which case the related forum threads may be equally enlightening.
Basically, the 3D pipeline is like this: CPU ---> VS (vertex shaders) ---> PS (pixel [actually fragment] shaders) + TMU (texture units) --> ROPs (render output processors: among other things, apply AA and write scene fragments as screen pixels to the framebuffer which in turn gets piped to your monitor). Obviously I'm glossing over a lot of detail, much of which you can glean from carefully reading the above reviews.
ALU = arithmetic logic unit, basically it does stuff to your data like ADD, MULtiply, MultiplyandADD, MultiplyandSUBstract, etc, etc. A pixel shader can be comprised of more than one ALU, and each so-called ALU can do more than operation (tho usually not at once, thus "ADD
/MUL
/MADD"). Googling can get you some nice diagrams of
R520 and
G70 capabilities, with all that crazy detail. I'm not even sure if those diagrams are entirely accurate, but they jive with what I've read. You can see how R520 has separated its TMUs (texture units), while G70 has its TMU integrated--or at least sharing transistors with--its first pixel shader unit.
Don't ask me to explain more, I'll just get you more mixed up. I'm not entirely clear on some distinctions, either (like if an ALU can technically only perform one or two functions, of if the term applies to a group of execution units, as those diagrams imply of G70's "FP32 Shader Unit 1). B3D also has some past articles that go into detail with AA and AF, which you might be interested in.
Now, enough of this 3D voodoo--I've got a toaster oven to research. Why can't I find one that consistently toasts without burning and doesn't melt a month after the warranty expires? WHY, DAMMIT, WHY?!