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Reviewed by: Bryan Pizzutti [11.12.01]
Manufactured by: Hercules
MSRP: $119.99


Did they do it right this time?

Recently, with the demise of 3DFX, the war for fastest video card has been narrowed down to two opponents: NVIDIA and ATI. And while both companies also release so-called "budget" cards, these tend to just be partially crippled versions of their higher-end cards, designed for all of the "price-conscious" people out there. High-performance, cutting-edge graphics cards have always cost an arm and a leg to a lot of people, and have been WAY out of many people's price ranges, including mine.

Enter a company called STMicroelectronics. They have designed a new graphics processor line, which they call "Kyro," officially known as the PowerVR Series 3. This processor, rather than being based on the same old 3D computational model used by NVIDIA and ATI, uses something called "Tile-based Rendering"

So, what's that mean, you ask? To do that will require a bit of explanation, and I'll be as concise as possible.

Conventional 3D cards, when receiving orders to draw 3D polygons on the screen and apply textures to them, simply do that. The program (be it a game or whatever) sends information about a scene, including all polygons contained in it, to the video card to render. This includes polygons, and parts of polygons, that are hidden from view by other polygons (Such as a character hiding behind a wall). Now, for a long time, this technology was more than sufficient, and to many extents, still is. However, this is what causes differences between advertised (also known as "theoretical") fill rates, and visible (what we tend to term as "actual") fill rates. As games get more complex, more and more polygons are generated that are hidden from view. Hence, as time has marched on, the difference between a card's theoretical and actual fill rates has grown larger.

Another factor affecting conventional 3D cards is a memory bottleneck. The RAM on a video card can only transmit so much data per second, depending on what speed and technology of memory chips they use, and how many bits "wide" the path between the graphics processor and the video RAM is. The crippled so-called "budget" video cards, tend to use SDR memory, as compared to high-end cards, which use DDR, which offers twice as much data transfer rate. Efforts are being made by companies to optimize the use of this limited pipe between the memory and the video processor (such as ATI's HyperZ technology), but the guys who made the Kyro had other ideas.

STMicro asked themselves, "Hey, how about taking all the stuff that the user isn't going to see out of the loop? Probably wouldn't need such fast memory, and the graphics processor wouldn't have to do so much work either!" So some of their researchers came up with the idea of receiving the scene from the program, and then splitting it up into a grid. Each tile in the grid is examined individually to see what will and will not be visible when texture rendering is complete, and the things that won't be visible are simply thrown away. Then the graphics processor computes the polygons and applies the visible textures to the visible surfaces and displays them. This saves so much memory bandwidth that, even with the fast-falling prices of DDR RAM chips, the chip is designed to use SDR RAM.

To illustrate this, we've asked our good friend Kevin Bacon to help us out (Kevin and Geoff the Goat go way back).

First, let's take a scenario where we have two Kevin Baconheads, one beside the other.  The Kyro II, and every other video card, will render each Baconhead in full form.

Now, let's say one Baconhead is partially obscuring the other... Most video cards will render all of Baconhead 1, and Baconhead 2, in full.  That's a whole lotta Bacon.

The Kyro II gets away with rendering all of Baconhead 1, but only part of Baconhead 2.  This is how deferred rendering works... The less Kevin Baconheads it has to render, the more bandwidth it has for more important things.  Thanks Kevin!

The first version of the Kyro ran at 125 MHz, and so did its memory. However, it never caught on with major video card manufacturers, and driver support wasn't the greatest in the world. Still, anyone who has owned a Sega Dreamcast has used the technology, since the predecessor to the Kyro (The PowerVR Series2) is the graphics chip that powers it.

The Prophet 4500, using the Kyro II chipset, is clocked up to 175 MHz and uses 175 MHz memory, though the specs from STMicro call for it to be clocked at 166 MHz.  No processor in the Kyro series yet offers a hardware transform-and-lighting engine, which is available on almost all chips from ATI and NVIDIA, though STMicro plans to implement one in the next version of their chip.  This should significantly help those with lower-end CPU's, and will further help establish the Kyro chipset as a great low-end solution.

Here's a small statistical comparison between the Kyro series and some other budget graphics chipsets it is competing directly with:

  Asus GeForce2 MX Visiontek GF2MX 400 Hercules Prophet 4500 ATI Radeon VE
CPU Clock 175 MHz 200 MHz 175 MHz 183 MHz
Memory Clock 166 MHz
SDR 64 bit
166 MHz
SDR 128 bit
175 MHz
SDR 128 Bit
183 MHz
DDR 64 Bit
Max Memory 64 MB 64 MB 64 MB 64 MB
Memory Bandwidth 1.3 GB/s 2.7 GB/s 2.8 GB/s 2.7 GB/s
Hardware T&L Yes Yes No Yes
Lowest Price $78.00 $88.00 $85.00 $65.95


Prices are approximate at time of writing, and were obtained from a low price search engine.  As you can see, price-wise it is one of the highest cards...  It is obviously directed at the GeForce 2 MX, so that's what we put it up against.

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