All transactions originate and terminate via a host port. The tunnel and single ended slave are considered peripherals or slaves. A switch passes data to and from one HyperTransport chain to another. Data Management One of the more complex data management tasks in a system is tracking a resource and mapping the available resource so the host can effectively utilize it. When the host writes to that address range, the HyperTransport logic transfers and then writes that data into the target device's memory without host processor intervention.
Commands are four bytes long and begin with a six-bit command type field.
The most common commands are Read Requests, Read Responses, and Writes. The remaining four bytes are command specific. When the command requires an address, the last byte of the command is concatenated with an additional four bytes to create the 40-bit address. As an example, it is possible to construct a fabric with a two bit wide physical link up-stream and an eight bit wide link down stream. The variable asymmetric width capability gives the designer the ability to allocated bandwidth specific to the needs of the system, simplifying PCB layout and reducing pin-count on ASICs.