Video

ATI: But yeah on the shaders we have 48 of what we call the adaptive shader array. So in the past you’ve had to say well here’s where I’m going to use my pixel shaders, and here’s how I’m going to use my vertex shaders, but in this particular case the hardware actually figures it all out for you and determines what the most efficient way to do that is.

So if you have a bunch of commands that are going to the VPU, and let’s say it requires a very light load of vertex shading, but a very heavy load of pixel shading, the developers don’t have to specify that. That is intelligently figured out by the VPU. So the VPU looks at the workload is and says, “okay here’s how I’m going to evenly distribute the workload”, so we call it the adaptive shader array.

FiringSquad: Onto the video processor, is it an on-die TV encoder or something like a Rage Theater-type chip? Would that be a third chip?

ATI: It is a third tiny chip and actually Microsoft did that. Microsoft if you recall acquired, about five or six years ago, acquired WebTV. So the people in Mountain View, CA that were a part of that group, and of course, it’s not just those people anymore, but they did that chip, and they’ve done a good job.

You know it’s a good choice because it’s a lot cheaper silicon, they’re using 90nm.

FiringSquad: Do you know if it supports dual HD displays?

ATI: No it doesn’t. I know the NVIDIA chip does, but that’s only because PC products do. It doesn’t seem to have a real use inside the living room, but maybe you differ with me on that.

FiringSquad: Well, on the Sony console, I think they’re looking at applications that go beyond just a console in the living room don’t you think?

ATI: Yeah I really think it’s just an accident because, well you know, last summer they had to change their plans. They found out that Cell didn’t work as well as they wanted to for graphics. Remember originally you had two or three Cell processors doing everything and then in August last year they had to take an NVIDIA PC chip. And as you know, all PC chips do this, and so it [dual HD display outputs] just came for free.

FiringSquad: What features does Xbox 360 have that really set it apart from what we know so far about RSX and PS3?

ATI: Well, it has a lot. I’ll go through the main features. It has a great anti-aliasing story, it has a powerful shading story, in that we can, well performance but also it has a rich instruction set, giving you great image quality and its flexibility.

It has lots of headroom. This is something that developers will find is easy to program for and rich enough to last for years. It has the performance and feature set to last for years.

We’d like to thank Bob Feldstein for taking the time out to answer our questions about Xbox 360’s graphics. As you can see, ATI’s gone well beyond what we see today in RADEON X850 XT. While Bob didn’t want to project how much more powerful the Xbox 360 VPU is over X850, clearly the chip sports many features that we won’t find in anything on the PC.