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The GeForce2 (NV15) is the second generation of NVIDIA's GeForce graphics processing units. Introduced in early 2000, it is the successor to the GeForce 256. The GeForce 2 family comprised a number of models: ''GeForce 2 GTS'', ''GeForce 2 Pro'', ''GeForce 2 Ultra'', ''GeForce 2 Ti'', ''GeForce 2 Go'' and the ''GeForce 2 MX'' series. In addition, the GeForce 2 architecture is used for the Quadro series on the Quadro 2 Pro, 2 MXR, and 2 EX cards with special drivers meant to accelerate computer-aided design applications. ==Architecture== The GeForce 2 architecture is similar to the previous GeForce 256 line but with various improvements. Compared to the 220 nm GeForce 256, GeForce 2 is built on a 180 nm manufacturing process, making the silicon more dense and allowing for more transistors and a higher clock speed. The most significant change for 3D acceleration is the addition of a second texture mapping unit to each of the four pixel pipelines. Some say the second TMU was there in the original Geforce NSR (NVIDIA Shading Rasterizer) but dual-texturing was disabled due to a hardware bug; NSR's unique ability to do single-cycle trilinear texture filtering supports this suggestion. This doubles the texture fillrate per clock compared to the previous generation and is the reasoning behind the GeForce 2 GTS's naming suffix: GigaTexel Shader (GTS). The GeForce 2 also formally introduces the NSR (Nvidia Shading Rasterizer), a primitive type of programmable pixel pipeline that is somewhat similar to later pixel shaders. This functionality is also present in GeForce 256 but was unpublicized. Another hardware enhancement is an upgraded video processing pipeline, called ''HDVP'' (high definition video processor). HDVP supports motion video playback at HDTV-resolutions (MP@HL). In 3D benchmarks and gaming applications, the GeForce 2 GTS outperforms its predecessor by up to 40%. In OpenGL games (such as Quake III), the card outperforms the ATI Radeon DDR and 3dfx Voodoo 5 5500 cards in both 16 bpp and 32 bpp display modes. However, in Direct3D games running 32 bpp, the Radeon DDR is sometimes able to take the lead. The GeForce 2 architecture is quite memory bandwidth constrained. The GPU wastes memory bandwidth and pixel fillrate due to unoptimized z-buffer usage, drawing of hidden surfaces, and a relatively inefficient RAM controller. The main competition for GeForce 2, the ATI Radeon DDR, has hardware functions (called HyperZ) that address these issues. Because of the inefficient nature of the GeForce 2 GPUs, they could not approach their theoretical performance potential and the Radeon, even with its significantly less powerful 3D architecture, offered strong competition. The later NV17 revision of the NV11 design, used for the GeForce 4 MX, was more efficient; although the GeForce 4 MX 460 was a 2x2 pipeline design, it could not outperform the GeForce 2 Ultra. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「GeForce 2 series」の詳細全文を読む スポンサード リンク
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