In an interview with Web site bit-tech.net , ATI Developer Relations Manager Richard Huddy waxed technical about Microsoft's upcoming Xbox 360 and ATI's role in the machine. The 360 will be using ATI's Xenos graphics processor, and Huddy's job is to chat with potential developers and help them develop the tools that best use Xenos' capabilities.
With regards to the console's architecture, Huddy says, "It's way better than I would have expected at this point in the history of 3D graphics." He sees the unified pipeline, rather than segregated pixel and vertex engines, giving the 360 a huge a huge advantage in accessible processing power.
Huddy goes on to shed some light on backwards compatibility. Each Xbox game is written with specific Xbox hardware in mind, and the 360's move to PowerPCs and ATI graphics doesn't jibe with the Xbox's Intel chips and Nvidia graphics processors. To add to the difficulty, the 360 wasn't designed for backward-compatibility early on in development.
To solve this, Microsoft has implemented the use of emulator programs that will allow the Xbox 360 to play Xbox games. According to Huddy, "emulating the CPU isn't really a difficult task. ...the real bottlenecks in the emulation are GPU calls--calls made specifically by games to the Nvidia hardware in a certain way. General GPU instructions are easy to convert--an instruction to draw a triangle in a certain way will be pretty generic. However, it's the odd cases, the proprietary routines, that will cause hassle." Once complete, the Xbox emulators could come pre-loaded on the unit's hard drive or will be downloadable via Xbox Live.
Huddy also dispels the notion of the PlayStation 3's higher graphics clock speed (550MHz versus the 360's 500MHz) means that Sony's console will outperform the Xbox 360. He believes that its ATI's unified pipeline that will make the biggest difference between the Xbox 360 and PS3. ATI archrival Nvidia, who is providing the RSX graphics processor for the PS3, has chosen not to go the route of a unified pipeline.
"This time around, [Nvidia doesn't] have the architecture and we do, so they have to knock it and say it isn't worthwhile. But in the future, they'll market themselves out of this corner, claiming that they've cracked how to do it best. But RSX isn't unified, and this is why I think PS3 will almost certainly be slower and less powerful."
By James Yu, Tim Surette -- GameSpot