Inside ATI's new Radeon 8500

Jewelle Schiedel-Webb
ATI Technologies Inc. is using this week's SIGGRAPH trade show in Los Angeles to unveil its next generation Radeon graphics chip architecture, as well as a set of new graphics cards to go along with the new chip. The good news from ATI is that both the flagship board and the flagship chip will be coming to the Macintosh.

"This changes everything."

That's the slogan that ATI is using to promote the new chip, called Radeon 8500. The chip sports an immensely complex design -- 60 million transistors packed onto a single chip, twice the count of the original Radeon, and more than a Pentium III and Pentium 4 chip put together, according to ATI's Director of Desktop Marketing, Jewelle Schiedel-Webb. This and a number of other innovations on the chip equate to an overall processing speed of 1 billion pixels per second, with 12 gigabytes per second peak memory bandwidth. In a meeting with MacCentral, Schiedel-Webb noted that the Radeon 8500 sports a 30x 3D performance increase compared to ATI's own RAGE Pro chip, which was state of the art only four generations ago.

Schiedel-Webb explained that the Radeon 8500 introduces a few brand new features, including the company's vaunted Truform and Smartshader technologies, as well as the heretofore unannounced Smoothvision, a new method of real-time anti-aliasing. Improvements to existing Radeon technologies have also been made. The Radeon 8500 features Charisma Engine II, Pixel Tapestry II, HyperZ II, and Video Immersion II.

New features

Since earlier this year, ATI has been promoting both Truform and Smartshader as technologies that would appear on its then-unannounced new graphics hardware. Now the hardware is announced.

Truform provides the capability to create high-order curved surface from objects with low polygon counts. The idea, in short, is to generate much more realistic, organic, rounded and curved shapes without needing to pump the details of a high-polygon model through the computer's CPU or over its bus. As a result, game and 3D application designers who use Truform can enable their applications to display more realistic organic 3D objects without significantly impacting the performance of the video card.

Smartshader provides developers with the ability to create their own heavily customized vertex and pixel-shading engines, which provide much more detailed lighting, shadowing and texture effects. By using Smartshader, developers can make ATI cards display realistic particle effects from waterfalls or torches, more realistic skin, ripples in water that react realistically, and much more.

Smoothvision is ATI's term for its new real-time anti-aliasing technology. Real-time anti-aliasing provides smoothing of jagged edges, an effect long seen in still images, but Smoothvision is applied to 3D graphics in real-time. Smoothvision is better than previous implementations of ATI's anti-aliasing technology because it uses random sampling methods. It's also programmable, enabling developers to program their own pixel sampling patterns.

Radeon 8500

Improved technology

Radeon 8500 also sports some new generations of existing technology, including Charisma Engine II, the latest implementation of the company's transform and lighting engine. In addition to the new programmable Smartshader technology that's built in, Charisma Engine II's fixed functions are faster, too.

HyperZ II is ATI's latest implementation of memory bandwidth management technology. HyperZ II helps the Radeon chip to manage the memory on board the card itself as effectively as possible. Improvements in this implementation of HyperZ all affect the z-buffer, an area in memory reserved for the z-axis value of each pixel -- which helps to determine the depth and location of an object in three dimensional space. HyperZ II improvements include a more efficient lossless compression algorithm, and a hierarchical z-buffer that discards data faster and reduces the amount of data that is "overdrawn" -- where pixels are calculated even though they are not drawn onscreen since they are obscured by other objects. All told, this generates a 20 percent performance improvement over Radeon, said ATI.

DVD playback is an important issue for many Mac users, too, and ATI has answered the call by improving Radeon 8500's video playback by developing Video Immersion II. The technology now features what Schiedel-Webb called "enhanced Adaptive De-interlacing and Temporal Filtering." It's a mouthful, but the bottom line is that the technology yields an even higher quality video image for output to either a TV set or to a computer monitor, or with the help of DVI-I to component output support, to an HDTV-ready source as well.

The proof of the pudding is in the eating

Although ATI is quick to favorably compare the Radeon 8500 to the original Radeon, the real competition is Nvidia's GeForce3 graphics chip. The high-end graphics processing unit already has a several month head start on the Radeon 8500, and is available from a variety of Nvidia card making licensees -- in fact, a board based on the GeForce3 chip is available as an build-to-order option for the Mac. So how does the Radeon 8500 stack up against the GeForce3?

ATI's own internal benchmarks show that the Radeon 8500 outpaces competitor Nvidia's GeForce3 graphics chip by a significant margin, depending on the Windows benchmark being considered. In real-world tests, the Radeon 8500 easily outpaced the GeForce3 in Quake 3 Arena -- 175 frames per second in 1024x768 resolution at a 16-bit color depth, versus 165 for the GeForce3; 170 frames per second at 1024x768 resolution, with 32-bit color turned on, versus 163 for the GeForce3. Comparative Mac benchmarks weren't available when we met with ATI, but Schiedel-Webb and her crew suggested that the Radeon 8500 was very competitive against the GeForce3 in Mac tests.

And if you're concerned about feature parity between Windows and Mac software drivers, worry not, said Schiedel-Webb. She said that although a few things may not work exactly the same way right off the bat, Radeon 8500's features are present both in Microsoft's DirectX API (used in Windows) and in OpenGL, which Apple prefers. And if the technology isn't in Apple's OpenGL drivers on day one, they should be fully exposed in future releases.

ATI said the Radeon 8500 card itself should ship in September and will carry a suggested retail price of US$399. Expect to hear more details about the Radeon 8500 Mac Edition around that time, too.

This story, "Inside ATI's new Radeon 8500" was originally published by PCWorld.

  
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