LSI Logic For more than a decade the PCI bus has been the backbone of personal computers. Other systems, such as telephony and networking, adopted the technology for its cost and performance advantages. But now the PCI bus is reaching its performance limits. No longer able to scale in either clock frequency or bus width, PCI bus has no more bandwidth gains to make. It is time for a replacement. Personal computer (PC) clock speeds have pushed to multiple GigaHertz. Networking and telephony applications are merging and demanding system throughputs in the hundreds of Megabytes per second. Meanwhile, the PCI bus that connects processors and their I/O resources is dragging along at a mere 133MHz. Something must change, yet the large installed base of hardware and software for PCI bus-based systems prevents designers from simply switching to a faster bus architecture. Systems need more bandwidth, but it must come with backward compatibility. The PCI Special Interest Group (PCI SIG) has solv