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Radeon 9700 White Paper

A very well written white paper covering the major internal workings of the DX9 compliant ATi R300 Visual Processing Unit along with our thoughts.

While we usually do not reproduce these papers in their entirety, we are going to make an exception with the ATi Radeon 9700. Our job is to decipher much of the cryptic language contained in these papers for our readers and try to point out the facts from the BS. This paper is a bit different from the usual, though. ATi has done such a good job writing the paper that you don't need an EE degree to understand it for the most part. While there is still a ton of tech jargon included, I think that most of you that want to read a something like this will be pleasantly surprised with how down to earth it is.

This is not the only R300/Radeon 9700 article we will be posting. We will have another article that covers our thoughts and experiences with the R300/9700 as well as a bit more information not covered here.

All of our comments from here on will be in yellow. Keep in mind that outside of our comments these are ATi's words, so there will be a bit of spin to take into account. Overall though it is an honest explanation about the internal workings of ATi's R300 VPU.

Before you dig in, we thought a few pictures of the card might be in order so that you can see that this is not vaporware by any stretch of the imagination. Please keep in mind that this card may not exactly represent the retail product, but it seems that it will be very close to what you will be laying down your hard earned green for.

White Paper - RADEON 9700 Architecture and Key Features

Introduction:

The RADEON 9700 is the most advanced graphics processor ever created. With 107 million transistors, it is a completely new architecture designed around the concepts of high bandwidth, parallelism, efficiency, precision, and programmability. The performance of this new architecture is staggering, more than doubling anything on the market today in every category:

As of yesterday morning the official transistor count number we got was "over 110 million, so the graphic above may be a bit dated, but the rest of the numbers seem to jive.

The reference above to bandwidth is surely talking about their 20GB/s of memory bandwidth backed up with 256-bit DDR. Parallelism is a bit more ambiguous though, and a few more conversations with engineers has uncovered the fact that the R300 VPU is capable of being utilized in a multi-VPU configuration with up to 256 R300 VPUs being utilized on a single "card". I know the first thing going through many of your heads is the bogus pictures we saw of the "8500 MAXX" product in the last couple weeks. When directly asked, ATi has once again stated that there are no plans to build a VidCard with two or more VPUs at the current time, although they could certainly do so. ATi did mention that there were certain government and military application that could take advantage of such an architecture, and they wanted to be able to be viable in that market.

Efficiency is referencing their very wide pipeline cluster and precision is certainly alluding to the floating point unit being taken advantage of now that will lead to colors being done "right" for a change. Integer math used in the past has certainly lead to less accurate colors being produced in the scenes we see in our games. This is also one of the advancements that will certainly lend itself to more lifelike characters and objects in the games we play. Programmability is almost self explanatory. Game developers can now write their own shaders to produce the effects they want.

The specs shown here are pretty staggering. The Memory Bandwidth, Transform rate, and Pixel Fill rate really stick out even compared to the previous crown holder, the GF4 Ti4600. Now we all know that specs on paper don't necessarily mean much, as illustrated by the Matrox Parhelia launch earlier this year. At the time of writing this, we have gotten to sit down and see a Radeon 9700 in action, and I can tell you that it has totally lived up to the specs that ATi is touting.

Here is the whole R300 VPU enchilada unrolled for your viewing pleasure. This white paper will be touching on all the interesting parts of the core that are profiled above.

AGP8X

The RADEON 9700 is the first available graphics processor to fully support the AGP 8X standard. The AGP bus provides the crucial high-bandwidth link between the graphics card and the rest of the PC. It carries a variety of different types of data, including 3D models, textures, shaders, drawing commands, and video streams.

AGP 8X is the latest revision of the AGP standard. It provides 2.0 GB/sec of bandwidth, which is twice that of the previous revision (AGP 4X). The additional bandwidth provided by AGP 8X is essential for demanding games and high-end workstation applications that need to pass a lot of data to the graphics processor. It enables faster load times and makes it possible to use higher resolution textures, more detailed 3D models, and more complex shader effects.

"Demanding Games" is what we really want to know about here for sure. In talking with engineers and PR folks from all the major 3D chipset makers, it would seem that as of this moment there are not really any games capable of truly utilizing the bandwidth provided by the AGP 8X specification. What we are hearing is that DOOM]|[ will certainly need that sort of bandwidth support to run properly as there are currently some scenes that are said to use upwards of 80MB of textures.