Advanced Interconnect Standards Blend Serial and Parallel Techniques for Best Performance and Scalability
Mario Cavalli General Manager HyperTransport Consortium
Executive Summary As modern computer architectures have pushed processor clock frequencies to 4 GHz, advanced I/O link technologies have embraced a number of new technologies and approaches to enable I/O data streams to keep up with processor speeds. It has become commonplace in the industry to think that parallel buses are old, slow and limited in bandwidth, and serial buses are newer, faster and enable higher bandwidth capabilities. But a new breed of interconnect technologies featuring the best of both serial and parallel bus features have emerged. This paper compares and contrasts serial and parallel bus characteristics and describes how these characteristics have come together in the HyperTransport and PCI Express interconnects.
Comparing Parallel and Serial Bus Characteristics In the past, common on-board computer bus architectures were purely parallel and off-board communication links were more often serial, better suited for signal shielding and long haul data transmission. The PCI (Peripheral Component Interconnect) bus, for example