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Manufacturer
ATI Technologies
Release Date
4/02/2002


ATI Radeon 8500
August 14, 2001 | Michael Eilers
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Charisma Engine II
The Charisma Engine is ATI’s fancy title for their fixed-calculation Transform, Clipping and Lighting processor. This feature went largely unused in the Radeon card, as game programmers are only now taking the time to design an engine that uses TCL effectively. ATI intends to solve that problem the same way NVIDIA did with the GeForce 3 – by adding support for features that will be built in to Microsoft’s DirectX 8.1 drivers as well as a future version of OpenGL. The primary enhancement of Charisma Engine II over the original is support for a programmable Vertex Shader pipeline, which is part of ATI’s Smartshader technology. For more on Smartshader, check out our feature on this technology later this week. This specialized processor can crank out 62.5 million triangles per second.

Pixel Tapestry II
As with Charisma Engine, this is a Radeon feature that again went largely unused, as its features required a game engine maker to program specifically with the card’s features in mind. This dead-end thinking ended after the original Radeon, however, as you might expect; as with the Charisma Engine, the new version of Pixel Tapestry aligns with DirectX 8.1 features and offers a programmable Pixel Shader pipeline as well. Again this falls under the category of ATI’s Smartshader technology, and we’ll go into detail in a follow-up article. So, you say you need textured pixels (also known as ‘texels’)? Well this version of Pixel Tapestry can crank out 2.4 gigatexels (yes, 2.4 BILLION textured pixels) a second.

Video Immersion Engine II
ATI has long been praised for fantastic 2D speed and image quality, and the Radeon 8500 chipset seems destined to carry on this legacy. Built around a 400 MHz DAC and featuring out-of-box support for two monitors (in fact three, if one is a television or VCR) this is no mere afterthought. The 2D feature set of this card is so strong it is shocking, incorporating features that rival professional broadcast equipment or HDTV tuners costing thousands of dollars.

The list of 2D features goes on and on: Hardware per-pixel adaptive deinterlacing, which allows for smooth, sharp video playback at any speed and rock-steady paused images; hardware DVD decoding (MPEG2) with full iDCT and motion compensation and hardware subpixel alpha support; on-the-fly YUV to RGB conversion, for studio-accurate color reproduction; programmable gamma and alpha blending features for realtime overlays. These are broadcast-quality features only available on so-called “turnkey” or paintbox systems just a few years ago.

Translated from geek-speak, these 2D features mean that if you play back video of any kind from any source, the Radeon 8500 will use its diverse feature set to give the video maximum image quality and smooth playback. As many Radeon owners have noted, using hardware MPEG1 compression on those cards you can actually increase the image quality of a movie by scaling it up to two or three times the original size, giving the subpixel adaptive scaling a chance to shine.

The 8500 includes a unique feature that again was previously only the domain of professional playback devices: the ability to synchronize any video source with your screen’s refresh rate regardless of the source frame rate. If you have watched a DVD or high-quality movie in the past that had a large amount of horizontal motion or rapid movement, you might have seen “tearing” – a clear horizontal break in the image when the refresh rate of the movie (24 fps, interpolated to 29.9 fps when converted to DVD) became momentarily out of sync with the actual refresh rate of your screen. With the 8500 this tearing is eliminated, as the 2D engine alpha-blends frames together on the fly to make sure the video syncs to your refresh rate, every time.

Additional 2D features include hardware QuickTime acceleration (Cinepack, MPEG-1 and AVI formats as well as Sorensen) – a feature PC users will not get. The card can also accelerate many video streams at once, rather than just the foreground window. While the initial version of this card will not have video input, the card layout and chipset was built with this feature in mind and it would be trivial for ATI or a third party to include it.



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