ATI Rage Pro

ATI is getting faster

Third generation of Rage architecture arrived in summer 1997. Rage Pro improved upon video of Rage II+DVD by 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 1.2 million triangles per second. 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 were 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 were 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. One weakness of previous Rage architecture remained- the inability to filter alpha blended textures. Considering long life time 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 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 should support also WRAM with external 250 MHz ramdac to exploit them at high resolutions, but I am not aware of any card taking advantage of that. 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 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 same clock of 75 MHz.
And here is the Rage Pro chip on an older Xpert@Work PCI card before the "Turbo" fiasco.

How could one not mention the Turbo disaster in a Rage Pro article. In 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 new product. Of course this was quickly exposed and 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 architecture replaced Rage II also in laptops, 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, which were serving as cheapest discrete offerings during 1999. And as an integrated graphics for servers it went on almost forever. Without improvements in 3d engine and no frequency bump (118 MHz memory clock wall is still there) the Rage XL is hair slower than Rage Pro because of SDRAM without block writes. The only added feature is integrated TMDS for flat panels. 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 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 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 gaming experience of R3 cards.

Playing like a Pro


Per-polygon mip mapping going wrong

I already mentioned bilinear filter optimization. Rage Pro has double the amount 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 complain 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 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 well also 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 chip 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 delivered the big success, Radeon 9700, a card with undisputed performance achievements and solid drivers from the start. And since Nvidia tripped over their shoelaces talent of ATI was no longer to be in doubt. What followed after was 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