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Released in late 1997 by Nvidia, the RIVA 128, or "NV3", was one of the first consumer graphics processing units to integrate 3D acceleration in addition to traditional 2D and video acceleration. Its name is an acronym for ''Real-time Interactive Video and Animation accelerator''.〔(RIVA 128 Brochure ), Nvidia, accessed October 9, 2007.〕 Following the less successful "NV1" accelerator, RIVA 128 was the first product to gain Nvidia widespread recognition. It was also a major change in technological direction for Nvidia. ==Architecture== Nvidia's "NV1" chip had been designed for a fundamentally different type of rendering technology, called quadratic texture mapping, a technique not supported by Direct3D. The RIVA 128 was instead designed to accelerate Direct3D to the utmost extent possible. It was built to render within the Direct3D 5 and OpenGL API specifications. The graphics accelerator consists of 3.5 million transistors built on a 350 nm fabrication process and is clocked at 100 MHz.〔 RIVA 128 has a single pixel pipeline capable of 1 pixel per clock when sampling one texture. It is specified to output pixels at a rate of 100 million per second and 25-pixel triangles at 1.5 million per second.〔 There is 12 KiB of on-chip memory used for pixel and vertex caches.〔 The chip was limited to a 16-bit (Highcolor) pixel format when performing 3D acceleration and a 16-bit Z-buffer. The 2D accelerator engine within RIVA 128 is 128 bits wide and also operates at 100 MHz. In this "fast and wide" configuration, as Nvidia referred to it, RIVA 128 performed admirably for GUI acceleration compared to competitors.〔(STB VELOCITY 128 REVIEW (PCI) ), Rage's Hardware, February 7, 1998.〕 A 32-bit hardware VESA-compliant SVGA/VGA core was implemented as well. Video acceleration aboard the chip is optimized for MPEG-2 but lacks full acceleration of that standard. Final picture output is routed through an integrated 206 MHz RAMDAC.〔 RIVA 128 had the advantage of being a combination 2D/3D graphics chip, unlike Voodoo Graphics. This meant that the computer did not require a separate 2D card for output outside of 3D applications. It also allowed 3D rendering within a window. The ability to build a system with just one graphics card, and still have it be feature-complete for the time, made RIVA 128 a lower-cost high-performance solution. Nvidia equipped RIVA 128 with 4 MiB of SGRAM, a new memory technology for the time, clocked at 100 MHz and connected to the graphics processor via a 128-bit memory bus.〔 This provides memory bandwidth of 1.60 gigabytes per second. The memory was used in a unified memory architecture that shared the whole RAM pool with both framebuffer and texture storage. The main benefit of this, over a split design such as that on Voodoo Graphics and Voodoo², was support for 3D resolutions of 800×600 and 960×720, higher than Voodoo's 640x480.〔(Review AGP Graphic Cards ), Tom's Hardware, October 27, 1997.〕 RIVA 128 was one of the early AGP 2X parts, giving it some more marketing headroom by being on the forefront of interface technology. The graphics processor was built around Intel's AGP specification targeting the Intel 440LX chipset for the Pentium II. Nvidia designed the RIVA 128 with a maximum memory capacity of 4 MiB because, at the time, this was the cost-optimal approach for a consumer 3D accelerator.〔http://developer.nvidia.com/object/RIVA_128_FAQ.html RIVA 128/ZX/TNT FAQ], Nvidia, accessed October 9, 2007.〕 This was the case partly because of the chip's capability to store textures in off-screen system RAM in both PCI or AGP configurations.〔 In early 1998, Nvidia released a refreshed version called RIVA 128 ZX. This refreshed design of NV3 increased memory support to 8 MiB and increased RAMDAC frequency to 250 MHz. These additions allowed RIVA 128 ZX to support higher resolutions and refresh rates.〔Covey, Alf. (STB Velocity 128 vs STB Velocity 128zx What is the difference? ), STB Technical Support, June 3, 1998.〕 The next major chip from Nvidia would be the RIVA TNT. 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「RIVA 128」の詳細全文を読む スポンサード リンク
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