HP Professional 8000 Highly Parallel System Architecture for Compaq Profession - Page 13

ECG066/1198 TECHNOLOGY BRIEF (cont.) ... The LX chipset supports an early version of AGP graphics. AGP provides a dedicated 66-MHz PCI bus connection between the graphics card, processor bus, and main memory. Full-AGP graphics systems are able to store texture and Z-buffer information into non-cacheable system memory. Additionally, future versions of AGP will support AGP bus master cycles that will allow the AGP card to transfer data on both clock-edges, providing a theoretical 533-MB/s graphics bandwidth. However, operating system support for AGP bus master cycles will not be available until mid-1998. AGP systems provide a 66-MHz PCI bus connection to the processor, while Highly Parallel System Architecture systems provide only a 33-MHz connection to the PCI buses. This increases the graphics bandwidth from 133 MB/s to 267 MB/s in current AGP systems, but this advantage can be deceiving. As Compaq testing shows, this increased bandwidth represents performance improvement of only about a one percent in most graphics-intensive applications. This very small increase occurs because graphics performance is limited mostly by CPU and graphics processor capability and only rarely by bus bandwidth. Compaq workstation engineering measurements show that the highest-end 3D-graphics cards typically require no more than 20 percent of a PCI bus, with peaks of up to 40 percent. Thus, PCI graphics cards still have headroom to double performance without saturating the PCI bus. The dual PCI buses in the Highly Parallel System Architecture in some cases provide more bandwidth than even a full AGP implementation. For example, in video editing, the dual PCI buses allow the application to manage three video streams, something that would not be feasible using only a single PCI bus implementation. Compaq Professional Workstations using the Highly Parallel System Architecture support industry-standard PCI-based 2D- and 3D-graphics solutions. In conjunction with dual-peer PCI buses, the Highly Parallel System Architecture graphics solutions provide highly competitive performance for workstation applications. For a more detailed comparison of the LX chipset and the Highly Parallel System Architecture, please refer to the technology brief Highly Parallel System Architecture vs. the Intel 440LX AGPset in the Workstation Market, document number ECG049/1097. CONCLUSION As business-critical applications become more demanding, the need for more bandwidth becomes increasingly important to customers. The new Highly Parallel System Architecture provides high performance and expansion capability plus unprecedented levels of bandwidth for X86 systems running Windows NT and very demanding applications. As the first computer company to implement this new architecture, Compaq once again demonstrates its technology leadership in providing innovative computing solutions to meet the needs of all its customers. 13