General
| HyperTransport provides a point-to-point interconnect that can be extended to support a wide range of devices. Figure 2-1 on page 21 illustrates a sample HT system with four internal links. HyperTransport provides a high-speed, high-performance, point-to-point dual simplex link for interconnecting IC components on a PCB. Data is transmitted from one device to another across the link. Figure 2-1. Example HyperTransport System The width of the link along with the clock frequency at which data is transferred are scalable:
This scalability allows for a wide range of link performance and potential applications with bandwidths ranging from 200MB/s to 12.8GB/s. At the current revision of the spec, 1.04, there is no support for connectors implying that all HyperTransport (HT) devices are soldered onto the motherboard. HyperTransport is technically an "inside-the-box" bus. In reality, connectors have been designed for systems that require board to board connections, and where analyzer interfaces are desired for debug. Once again referring to Figure 2-1, the HT bus has been extended in the sample system via a series of devices known as tunnels. A tunnel is merely an HT device that performs some function, but in addition it contains a second HT interface that permits the connection of another HT device. In Figure 2-1, the tunnel devices provide connections to other I/O buses:
The end device is termed a cave, which always represents the termination of a chain of devices that all reside on the same HT bus. Cave devices include a function, but no additional HT connection. The series of devices that comprise an HT bus is sometimes simply referred to as an HT chain. Additional HT buses (i.e. chains) may be implemented in a given system by using a HT-to-HT bridge. In this way, a fabric of HT devices may be implemented. Refer to section entitled, "Extending the Topology" on page 33 for additional detail.  |
EAN: 2147483647
Pages: 182