Radeon 8000 series
The R200 is the second generation of GPUs used in Radeon graphics cards and developed by ATI Technologies. This GPU features 3D acceleration based upon Microsoft Direct3D 8.1 and OpenGL 1.3, a major improvement in features and performance compared to the preceding Radeon R100 design. The GPU also includes 2D GUI acceleration, video acceleration, and multiple display outputs. "R200" refers to the development codename of the initially released GPU of the generation. It is the basis for a variety of other succeeding products. Architecture. R200's 3D hardware consists of 4 pixel pipelines, each with 2 texture  sampling units. It has 2 vertex shaders and a legacy Direct3D 7 TCL unit, marketed as "Charisma Engine II". It is ATI's first GPU with programmable pixel and vertex processors, called "Pixel Tapestry II" and compliant with Direct3D 8.1. R200 has advanced memory bandwidth saving and overdraw reduction hardware called "HyperZ II" that consists of occlusion culling (hierarchical Z), fast z-buffer clear, and z-buffer compression. The GPU is capable of dual display output ("HydraVision") and is equipped with a video decoding engine ("Video Immersion II") with adaptive hardware deinterlacing, temporal filtering, motion compensation, and iDCT. R200 introduced  pixel shader version 1.4 (PS1.4), a significant enhancement to prior PS1.x specifications. Notable instructions include "phase", "texcrd", and "texld". The phase instruction allows a shader program to operate on two separate "phases" (2 passes through the hardware), effectively doubling the maximum number of texture addressing and arithmetic instructions, and potentially allowing the number of passes required for an effect to be reduced. This allows not only more complicated effects, but can also provide a speed boost by utilizing the hardware more efficiently. The "texcrd" instruction moves the texture coordinate values of a texture into the destination register, while the "texld  instruction will load the texture at the coordinates specified in the source register to the destination register. Compared to R100's 2x3 pixel pipeline architecture, R200's 4x2 design is more robust despite losing one texture unit per pipeline. Each pipeline can now address a total of 6 texture layers per pass. The chip achieves this by using a method known as 'loop-back'. Increasing the number of textures accessed per pass reduces the number of times the card is forced into multi-pass rendering. The texture filtering capabilities of R200 are also improved over its predecessor. For anisotropic filtering	Radeon 8000 series
19059340	, Radeon 8500 uses a technique similar to that used in R100, but improved with trilinear filtering and some other refinements. However, it is still highly angle-dependent and the driver sometimes forces bilinear filtering for speed. NVIDIA's GeForce 4 Ti series offered a more accurate anisotropic implementation, but with a greater performance impact. R200 has ATI's first implementation of a hardware-accelerated tessellation engine (a.k.a. higher order surfaces), called Truform, which can automatically increase the geometric complexity of 3D models. The technology requires developer support and is not practical for all scenarios. It can undesirably round-out models	Radeon 8000 series
19059341	. As a result of very limited adoption, ATI dropped TruForm support from its future hardware. Performance. Radeon 8500's biggest disappointment was its early driver releases. At launch, the card's performance was below expectations and it had numerous software flaws that caused problems with games. The chip's anti-aliasing support was only functional in Direct3D and was very slow. To dampen excitement for 8500, competitor nVidia released their Detonator4 driver package on the same day as most web sites previewed the Radeon 8500. nVidia's drivers were of better quality, and they also further boosted the GeForce 3	Radeon 8000 series
19059342	's performance. Several hardware review sites discovered that the performance of the Radeon 8500 in some actual game tests was lower than benchmarks reflected. For example, ATI was detecting the executable Quake3.exe" and forcing the texture filtering quality to much lower than normally produced by the card. HardOCP was the first hardware review web site to bring the issue to the community, and proved its existence by renaming all instances of "Quake" in the executable to "Quack." The result was improved image quality, but lower performance. However, even with the Detonator4 drivers, the Radeon 8500 was able to outperform the  GeForce 3 (which the 8500 was intended to compete against) and in some circumstances its faster revision, the Ti500, the higher clocked derivative Nvidia had rolled out in response to the R200 project. Later, driver updates helped to further close the performance gap between the 8500 and the Ti500, while the 8500 was also significantly less expensive and offered additional multimedia features such as dual-monitor support. Though the GeForce 3 Ti200 did become the first DirectX 8.0 card to offer 128 MiB of video memory, instead of the common 64 MiB norm for high-end cards of the time , it turned out that the GeForce 3's limitations prevented it from taking full advantage of it, while the Radeon 8500 was able to more successfully exploit that potential. In early 2002, to compete with the cheaper GeForce 3 Ti200 and GeForce 4 MX 460, ATI launched the slower-clocked 8500LE (known as 9100 in Europe) which became popular with OEMs and enthusiasts due to its lower price, and overclockability to 8500 levels. Though the GeForce 4 Ti 4600 took the performance crown, it was a top line solution that was priced almost double that of the Radeon 8500 (MSRP  of US$350–399 versus US$199), so it did not offer direct competition. With the delayed release of the potentially competitive GeForce 4 Ti 4200, plus ATI's initiative in rolling out 128 MiB versions of the 8500/LE kept the R200 line popular among the mid-high performance niche market. The greater features of the All-In-Wonder (AIW) Radeon 8500 DV and the AIW Radeon 8500 128 MB proved superior to Nvidia's Personal Cinema equivalents which used the faster GeForce 4 Ti 4200. Implementations. Radeon 8500/8500LE. ATI's first R200-based card was the "Radeon 8500", launched  in October 2001. In early 2002, ATI launched the "Radeon 8500LE" (re-released later as the "Radeon 9100" in Europe), an identical chip with a lower clock speed and slower memory. Whereas the full 8500 was clocked at 275 MHz core and 275 MHz RAM, the 8500LE was clocked more conservatively at 250 MHz for the core and 200 or 250 MHz for the RAM. Both video cards were first released in 64 MB DDR SDRAM configurations; the later 128 MB Radeon 8500 boards received a small performance boost resulting from a memory interleave mode. In November 2001 was the  release of the "All-In-Wonder Radeon 8500 DV", with 64 MB and a slower clock speed like the 8500LE. In 2002, three 128 MB cards were rolled out, the Radeon 8500, 8500LE, and the "All-In-Wonder Radeon 8500 128 MB", which was clocked at full 8500 speeds but had fewer video-related features than the AIW 8500 DV. ATI claimed that the lower clock speed for the 8500DV was due to the FireWire interface. Radeon 8500XT (canceled). An updated chip, the "Radeon 8500XT" (R250) was planned for a mid-2002 release, to compete against the GeForce 4 Ti line , particularly the top line Ti 4600 (which retailed for an MSRP of $350–399 USD). Prerelease information touted a 300 MHz core and RAM clock speed for the "R250" chip. A Radeon 8500 running at 300 MHz clock speeds would have hardly defeated the GeForce 4 Ti4600, let alone a newer card from NVIDIA. At best it could have been a better performing mid-range solution than the lower-complexity Radeon 9000 (RV250, see below), but it would also have cost more to produce and would have been poorly suited to the Radeon 9000's dual laptop/desktop roles due  to die size and power draw. Notably, overclockers found that Radeon 8500 and Radeon 9000 could not reliably overclock to 300 MHz without additional voltage, so undoubtedly R250 would have had similar issues because of its greater complexity and equivalent manufacturing technology, and this would have resulted in poor chip yields, and thus, higher costs. ATI, perhaps mindful of what had happened to 3dfx when they took focus off their "Rampage" processor, abandoned the R250 refresh in favor of finishing off their next-generation DirectX 9.0 card which was released as the Radeon 9700. This proved to be a wise  move, as it enabled ATI to take the lead in development for the first time instead of trailing NVIDIA. The new Radeon 9700 flagship, with its next-generation architecture giving it unprecedented features and performance, would have been superior to any R250 refresh, and it easily took the performance crown from the Ti4600. Drivers. Unix-related operating systems. The open-source drivers from X.org/Mesa support almost all features provided by the R200 hardware. They are shipped by default on most BSDs and Linux systems. Newer ATI Catalyst drivers do not offer support for any R500 or older architecture product. Windows  drivers. This series of Radeon graphics cards is supported by AMD under Microsoft Windows operating systems including Windows XP (except x64), Windows 2000, Windows Me, and Windows 98. Other operating systems may have support in the form of a generic driver that lacks complete support for the hardware. Driver development for the R200 line ended with the Catalyst 6.11 drivers for Windows XP. Mac OS and Mac OS X. Apple never shipped a Radeon 8000 series graphics card with any Power Mac, either stock or BTO, preferring to jump directly from the Radeon 7000 series (which was only available as  a BTO option on the Power Mac G4 "Digital Audio") to the Radeon 9000 (as the default graphics card on most Power Mac G4 "Mirrored Drive Doors" models). Instead, various Nvidia cards filled the gap. However, ATI themselves released a retail 8500 Mac Edition, compatible with Mac OS 9.2.2 and Mac OS X and targeted at Mac gamers, but despite the name the card was actually based on the 8500LE with a 250 MHz clock and 64MB of memory. MorphOS. The R200 series of Radeon graphics cards is supported by MorphOS.