Radeon R100

Radeon 7000 Series

Codename(s)	Rage 6C
Created in year	2000
Entry-level cards	7000/VE, SDR, LE
Mid-range cards	32 DDR, 7200
High-end cards	64 DDR VIVO (SE), 7500
Direct3D support	7.0

The Radeon R100 is the first generation of Radeon graphics chips from ATI Technologies. The line features 3D acceleration based upon Direct3D 7.0 and OpenGL 1.3, a major improvement in features and performance compared to the preceding Rage design. The processors also include 2D GUI acceleration, video acceleration, and multiple display outputs. "R100" refers to the development codename of the initially released GPU of the generation. It is the basis for a variety of other succeeding products.

Development

Architecture

The first-generation Radeon GPU was launched in 2000, and was initially code-named Rage 6 (later "R100"), as the successor to ATI's aging Rage 128 which was unable to compete with the GeForce 256. ATI called Radeon the first Visual Processing Unit (VPU) and it was built on a 180 nm semiconductor manufacturing process.

With respect to the 3D hardware within Radeon, the processor can write 2 pixels to the framebuffer and sample 3 texture maps per pixel per clock. This is commonly referred to as a 2x3 configuration. Of Radeon's competitors, the 3dfx Voodoo 5 5500 is a 4x1 design and the GeForce2 GTS is 4x2. Unfortunately, the third texture unit did not get much use in games during the card's lifetime because software was not frequently performing more than dual texturing.

Radeon also introduced a new memory bandwidth optimization and overdraw reduction technology called HyperZ. It basically improves the overall efficiency of the 3D rendering processes. Consisting of 3 different functions, it allows the Radeon to perform very competitively compared to competing 2 and 4 pipeline designs.

ATI's "Radeon's Ark" real-time demo

ATI produced a real-time demo for their new card, to showcase its new features. The "Radeon's Ark" demo presents a science-fiction environment with heavy use of features such as multiple texture layers for image effects and detail. Among the effects are environment-mapped bump mapping, detail textures, glass reflections, mirrors, realistic water simulation, light maps, texture compression, planar reflective surfaces, and portal-based visibility.[1]

In terms of performance, Radeon scores lower than the GeForce2 in most benchmarks, even with HyperZ activated. The performance difference was especially noticeable in 16-bit color, where both the GeForce2 GTS and Voodoo 5 5500 were far ahead. However, the Radeon could close the gap and occasionally outperform its fastest competitor, the GeForce2 GTS, in 32-bit color.

Aside from the new 3D hardware, the also Radeon introduced per-pixel video-deinterlacing to ATI's HDTV-capable MPEG-2 engine.

R100's pixel shaders

R100-based GPUs have programmable shading capability in their pipelines; however, the chips are not flexible enough to support the Microsoft Direct3D specification for Pixel Shader 1.1. A forum post by an ATI engineer in 2001 clarified this:

“ ...prior to the final release of DirectX 8.0, Microsoft decided that it was better to expose the RADEON's and GeForce{2}'s extended multitexture capabilities via the extensions to SetTextureStageState() instead of via the pixel shader interface. There are various practical technical reasons for this. Much of the same math that can be done with pixel shaders can be done via SetTextureStageState(), especially with the enhancements to SetTextureStageState() in DirectX 8.0. At the end of the day, this means that DirectX 8.0 exposes 99% of what the RADEON can do in its pixel pipe without adding the complexity of a "0.5" pixel shader interface. Additionally, you have to understand that the phrase "shader" is an incredibly ambiguous graphics term. Basically, we hardware manufacturers started using the word "shader" a lot once we were able to do per-pixel dot products (i.e. the RADEON / GF generation of chips). Even earlier than that, "ATI_shader_op" was our multitexture OpenGL extension on Rage 128 (which was replaced by the multivendor EXT_texture_env_combine extension). Quake III has ".shader" files it uses to describe how materials are lit. These are just a few examples of the use of the word shader in the game industry (nevermind the movie production industry which uses many different types of shaders, including those used by Pixar's RenderMan). With the final release of DirectX 8.0, the term "shader" has become more crystallized in that it is actually used in the interface that developers use to write their programs rather than just general "industry lingo." In DirectX 8.0, there are two versions of pixel shaders: 1.0 and 1.1. (Future releases of DirectX will have 2.0 shaders, 3.0 shaders and so on.) Because of what I stated earlier, RADEON doesn't support either of the pixel shader versions in DirectX 8.0. Some of you have tweaked the registry and gotten the driver to export a 1.0 pixel shader version number to 3DMark2001. This causes 3DMark2001 to think it can run certain tests. Surely, we shouldn't crash when you do this, but you are forcing the (leaked and/or unsupported) driver down a path it isn't intended to ever go. The chip doesn't support 1.0 or 1.1 pixel shaders, therefore you won't see correct rendering even if we don't crash. The fact that that registry key exists indicates that we did some experiments in the driver, not that we are half way done implementing pixel shaders on RADEON. DirectX 8.0's 1.0 and 1.1 pixel shaders are not supported by RADEON and never will be. The silicon just can't do what is required to support 1.0 or 1.1 shaders. This is also true of GeForce and GeForce2.”

Implementations

Radeon DDR box (R100)

Radeon 7500 (RV200)

R100

The first versions of the Radeon (R100) were the Radeon DDR, available in Spring 2000 with 32 MB or 64 MB configurations; the 64 MB card had a slightly faster clock speed and added VIVO (video-in video-out) capability. These cards were produced until mid-2001, when they were essentially replaced by the Radeon 7500 (RV200).

A slower and short-lived Radeon SDR (with 32 MB SDRAM memory) was added in mid-2000 to compete with the GeForce2 MX.

Also in 2000, an OEM-only Radeon LE arrived. It is a feature-reduced variant made by Athlon Micro. The card runs at a lower 143 MHz clock rate for both RAM and GPU, and it lacks Hyper Z functionality. It is possible to enable HyperZ through a system registry alteration to regain the lost performance. Later drivers do not differentiate the Radeon LE from other Radeon R100 cards and the HyperZ hardware is enabled by default, causing visual anomalies on cards with HyperZ hardware that is defective.

In 2001, a short-lived 64 MB SDR Radeon called the Radeon 7200 was released. After the older Radeon cards were discontinued, they also became known as Radeon 7200.

RV100

A budget variant of the R100 hardware was created and called the Radeon VE, later known as the Radeon 7000. RV100 has only one pixel-pipeline, no hardware T&L, a 64-bit memory bus, and no HyperZ. It did however add "Hydravision" dual-monitor support and integrated a 2nd RAMDAC into the core (for "Hydravision").

From the 3D performance standpoint, RV100 did not fare well against the GeForce2 MX of the same era. Its multi-display support and was a clear advantage, however. RV100 was later used as a Mobility Radeon notebook solution.

RV200

The Radeon 7500 (RV200) is based on a newer 150 nm manufacturing process. The increased density and various tweaks to the architecture allowed the GPU to function at higher clock speeds. It also allowed the card to operate with asynchronous clock operation, whereas the original "R100" was always clocked synchronously with the RAM. It was ATI's first Direct3D 7-compliant GPU to include dual-monitor support (Hydravision). Radeon 7500 launched in the second half of 2001 alongside the Radeon 8500. A Mobility Radeon 7500 for mobile applications launched later.

The desktop Radeon 7500 board frequently came clocked at 290 MHz core and 230 MHz RAM. It competed with the GeForce2 Ti and GeForce 2 Pro, and later on, the GeForce4 MX440.

Models

Competing chipsets

• NVIDIA GeForce 256 and GeForce2
• PowerVR Series 3
• 3dfx Voodoo 5

See also

• ATI Technologies
• Comparison of ATI Chipsets

References

• "ATI Radeon 256 Preview" by Anand Lal Shimpi, AnandTech.com, April 25, 2000, retrieved January 17, 2006
• "ATI Radeon 32MB SDR" by Anand Lal Shimpi, AnandTech.com, October 13, 2000, retrieved January 17, 2006
• "ATI Radeon 64MB DDR" by Matthew Witheiler, AnandTech.com, July 17, 2000, retrieved January 17, 2006
• "Beyond3D 3D Tables" Beyond3D.com, retrieved January 17, 2006
• Vlachos, Alex. Radeon's Ark demo, 2000.