HP Professional 8000 Highly Parallel System Architecture for Compaq Profession - Page 12

ECG066/1198 TECHNOLOGY BRIEF (cont.) ... AGPset Architecture The 440LX AGPset (LX chipset) from Intel is designed primarily for the commercial desktop and consumer desktop markets. However, some workstation vendors are deploying the LX chipset in machines targeted for workstation applications. Key features of the LX architecture include • Single PCI bus • Single memory bus • 66-MHz SDRAM memory • Advanced graphics port (AGP) bus for graphics cards • Support for up to two Intel Pentium II processors Figure 9 illustrates the LX chipset architecture. The microprocessor, memory, and AGP graphics buses operate with a peak bandwidth of 533 MB/s, while the peak bandwidth of the PCI bus is 133 MB/s. This contrasts with the 1.07-GB/s peak memory bandwidth and the 267-MB/s PCI bus bandwidth of the Highly Parallel System Architecture. A single memory controller provides maximum bandwidth of 533 MB/s. CPU CPU A single PCI bus provides 133 MB/s bandwidth for all attached I/O devices Memory Controller AGP Controller PCI Controller Disk Graphics Controller The AGP bus provides a dedicated path for the graphics controller to communicate with main memory and processors. The AGP-to-memory bus provides bandwidth of 533 MB/s. Figure 9. Block diagram of the LX architecture. PCI Slots and other Devices SCSI Controller The Highly Parallel System Architecture supports industry-standard EDO memory arranged in 2:1 interleaved banks. The LX architecture uses 66-MHz SDRAM technology, which Compaq projects to be a very short-lived technology, based on imminent microprocessor and system architecture advancements. Specifically, Compaq expects that 100-MHz SDRAM will be available as soon as 100-MHz host-bus systems are available-sometime in the first half of 1998. Since dual-processor LX workstations are not expected to be generally available until sometime during the fourth quarter 1997, the 66-MHz SDRAM for workstations may have a useful life of only about four to six months. Large purchases of 66-MHz SDRAM could result in large obsolescence costs as early as next year, when users migrate to higher performance 100-MHz SDRAM technology. This can be a significant expense for customers, as most workstation applications require large memory configurations. The Highly Parallel System Architecture, on the other hand, uses proven EDO memory technology that is supported by other Compaq enterprise products. Customers who plan to migrate to 100-MHz SDRAM next year will be able to protect and fully amortize their investment in EDO memory by redeploying the EDO memory into other systems, such as ProLiant servers and other workstations. 12