HP Professional AP500 Compaq Professional Workstation AP500 Key Technologies W - Page 9

WHITE PAPER (cont'd) Compaq Workstations - Key Technologies ACCELERATED GRAPHICS PORT (AGP) Today's three-dimensional graphic applications consume large amounts of memory bandwidth. Consequently, the proliferation of 3D applications is increasing the need for high-speed access to larger amounts of graphics memory. AGP is an industry standard solution to improve the bandwidth between the graphics accelerator and the system memory so that a portion of the 3D rendering data structures can be shifted into main memory. The higher bandwidth of AGP (compared to PCI) also improves sharing rendering tasks between the system processor and the graphics accelerator. AGP improves system performance by establishing pipelined access to the system's main memory and effectively reducing latency. AGP also transfers data up to four times faster than PCI, utilizing the bandwidth of a 100-MHz system memory bus more efficiently. The maximum data transfer rate of AGP is 533 MB/s, compared to 133 MB/s for PCI. CUSTOMER BENEFITS Some specific applications that can benefit from AGP include: • Video applications, like conferencing or DVD playback, where a steady stream of images must be sent from system memory to the graphics frame-buffer for display. • Graphics command lists, such as lengthy data sets defining vertices for 3D objects. • Texture memory for 3D rendering, where textures are overlaid on 3D objects for realistic effects. To improve realism, texture sizes will grow to 32 MB and beyond in 1999. Note: 3D texture data is the most immediate and important target opportunity for AGP. By shifting texture data to system memory, bandwidth load and memory size can be balanced between system and local graphics frame-buffer memory. The bandwidth and space required for textures are split between the heavily loaded frame-buffer and the (comparatively) lightly loaded system memory. Since texture data is not persistent (unlike display buffers), system memory used for texture data is returned to the free memory heap when a 3D application concludes. To gain the full benefit of AGP performance, the system must have the following features: • Pentium II class microprocessors Note: While AGP could be adapted to Pentium-class processors, the floating point and processing power of the Pentium II class products are a better fit. • AGP Sideband and Pipeline functions in the core logic, which improve data transfer efficiency • 100-MHz system memory architecture to meet system processor and AGP bandwidth demands • Microsoft Windows® 95 OSR2.1, Windows 98, or Windows NT® 5.0 operating systems to provide necessary memory management services Note: Windows NT 4.0 can operate AGP subsystems as PCI 66MHz-type devices only. 9