ATI Rage Pro

ATI is getting faster

The third generation of Rage architecture arrived in summer 1997. Rage Pro improved upon the video of Rage II+DVD by the addition of motion compensation, but most innovations were done on the 3d pipeline. To start from bus Rage Pro fully supports AGP 1.0, 133 MHz speed with execute from system memory, pipelining and sideband addressing. Command FIFO was extended to 128 levels. ATI also for the first time integrated a triangle setup engine greatly off-loading CPU. Peak processing rate is stated to be 1.2 million triangles per second, definitely respectable number in 1997. Geometry transformation defects of Rage II are gone, I did not notice any perspective errors. Texturing engine can now enjoy 4 kB cache, drastically reducing bandwidth demands of interpolation and enabling single pass free trilinear filtering. However as was common at the time, trilinear here stands for mere dithering between mip maps, not actual blending. ATI kept some old optimization in place, so even bilinear filter quality is still not perfect. High resolution and composited textures are supported. Very interesting was speculation about multitexturing capabilities of the texture unit. Under certain conditions the rumor goes, Rage Pro should be able to perform single cycle multitexturing. However, in games I was not able to find any situation where enabled multitexturing would increase performance. Perhaps the rumor was spawned by the "trilinear" claim. 45 million sustained bilineary filtered texels per second ain't bad anyway. Support for texture fog and specular highlights was added as well. However, one weakness of previous Rage architecture remained, the inability to filter alpha blended textures. Considering the long lifetime of the Rage Pro architecture, this should not have happened and caused image quality issues in years when such omission was no longer tolerable. If it was a design choice, the motivation behind it is a mystery to me. Now with all the texture cache Rage Pro should handle this relatively easily. Memory bus width is 64-bit wide, but SGRAM clock was raised to 100 MHz, delivering 800 MB/s peak bandwidth. The chip also supports WRAM with external 250 MHz ramdac to exploit them at high resolutions, but such cards were only made for Apple computers. ATI's effort to bite into professional market is also clear from addition of edge anti-aliasing. In the consumer world, there were few Rage Pro cards reusing old Rage II PCB with EDO memory (the slowest Rage Pro you can get) or Rage IIc PCB with SDRAM.

Just for kicks I picked my All-in-Wonder for the test, in the end, all Rage Pro's have the same clock of 75 MHz.
And here is the Rage Pro chip on an older Xpert@Work PCI card before the "Turbo" fiasco.

Click on the image to see late Rage Pro Turbo with 8 MB of plain SDRAM.

How could one not mention the Turbo disaster in a Rage Pro article. At the beginning of 1998 happened interesting PR attempt to fake technological update. With the new driver strongly optimized for popular synthetic benchmark and "Turbo" printed next to Rage Pro on chips ATI tried to create a new product. Of course, this was quickly exposed and the company covered in shame. Nevertheless, sales were going strong and R3 architecture was to be found in newer and actually updated chips.

Second life

Rage Pro replaced Rage II also in laptops, the LT version of the chip came one year later. It added LVDS, advanced power management and TV-out into the R3, enabling rich multimedia experience for notebooks. It is codenamed mach64LB and as you see the chip was used for discrete cards as well.


The long life of R3 architecture after die shrink. Developers were not pleased.

When 0.25 um manufacturing became available ATI adopted the R3 and created mach64GM core, used in Rage XL and XC cards. Serving as the cheapest discrete offerings during 1999. And as an integrated graphics for servers it went on almost forever. Besides 10 % higher clock speed, there was one notable improvement to the 3d engine- finally, all kinds of textures can be bilineary filtered. Coupled with faster SDRAM the Rage XL is the best form of the architecture, as long as 64-bit memory bus remained. The whole mach64 line was concluded with mach64LM core of Rage Mobility, power efficient chip with added iDCT. Such respins helped to prolong support for Rage Pro. Final driver used for my tests is the newest among everything I tried and is probably the only one with optimization for my system. It should be remembered that ATI also needed many years to fix major issues, deliver an adequate OpenGL driver, like one which would not crash your PC within several minutes of GLQuake. Actually, after two freezes doing only timedemos I am not sure if they ever really got it stable. Which brings me to the gaming experience.

Playing like a Pro


Per-polygon mip mapping going wrong

I already mentioned bilinear filter optimization. Rage Pro has double the number of gradients over Rage II and it is enough to not be perceived at first look, but still is far from proper filtering. ATI dragged this filter into next gen Rage 128 as well and fortunately for them almost nobody noticed. Another complaint is about reduced amount of texture samples at smaller mip levels, this creates obvious shimmering. The amount is about the same as for Rage II, but this time is less expected since Rage Pro was supposed to have high quality texturing engine and "free" trilinear filter will not compensate for such deficiencies. Also, mip mapping in advanced games like Unreal is still doing wrong mip selections, so I disabled it again. At least sub-pixel accuracy was significantly improved but there are still some polygon gaps to be seen in few games. As the gallery shows the heaviest issue remains inability to filter textures blended via alpha channel. Quake 3 even has special rendering path doing this filtering in software, but in some scenarios like with teleports the Rage Pro has to do the job on its own and leave some non-interpolated texel blocks on screen. ATi also never really excelled in 16-bit quality. Instead, they went for big true color leap ahead with next architecture.






Not quite there yet, but ATi found it sufficient for years to come.










Performance

When it comes to framerates Rage Pro with same bus and memory capacity equals both minimal and average results of Voodoo Graphics. With AGP and 8 MB it edges one year older 3dfx wonderboy by a small margin.

Merely tying the fastest chipsets on the market (with mature drivers), Xpert cards were not exactly gamers dream. However, Ati successfully used the "complete multimedia solution" buzz and could set attractive pricing.

Finishing words

The Rage Pro line may have not been warmly welcomed by gamers in retail, but strong OEM deals were feeding the company better then ever. ATI entered 1998 like a graphics giant with more than 1,000 employees and during the year topped number of 3d chips sold, many of them integrated on motherboards. Between companies designing high performance 3d accelerators ATI was among last to deliver dual pipeline architecture. But when it arrived at the end of the year in the form of Rage 128, it also demonstrated very advanced design with "full speed" 32-bit depth rendering. The architecture performed adequately after 1999 "Pro" update, but ATI still wasn't getting under the skin of gamers. To win also in retail earlier availability and good initial drivers were needed. The former being easier to fix, Radeon entered the market in the middle of 2000 as a first direct competition to Nvidia's TnL chips. ATI showed cleverly balanced resources and in rapidly consolidated market suddenly became the only "real" threat to what was shaping like Nvidia's complete domination. At the end of 2001 Radeon 8500 arrived, and while it had some performance problems in the beginning, it also showed a more advanced shading architecture than Nvidia's. In 2002 finally all the efforts converged in the big success of Radeon 9700, a card with undisputed performance achievements and solid drivers from the start. And since Nvidia tripped over their shoelaces the talent of ATI was no longer to be in doubt. What followed after was a series of ATI vs Nvidia battles without a clear conclusion. These cyclical encounters are continuing till today, now of course the ATI brand is hidden under AMD. The takeover of ATI had some critics, but the trend of the future seems to be a convergence of CPU and graphics back into a single device and in this regard AMD is doing very well. Who knows when, but the day will come when 3d accelerator as we use it will be unknown to gamers. ATI itself had a strong record of growing through acquisitions, in this order they absorbed Tseng Labs, Chromatic, Artist, ArtX, XGI and BitBoys.

ATI Performance summary