HyperTransport is a point-to-point interconnect with two unidirectional links (see Figure 1) that
directly connect the processors to each other and connect each processor to its dedicated memory
banks, as well as to other I/O chipsets.
HyperTransport has the advantages of no overhead for bus arbitration and easier signal integrity
maintenance, resulting in a scalable, high-bandwidth architecture.
Each16-bit (2-byte) HyperTransport link is double-pumped, performing two data transfers per clock
cycle. From HyperTransport 1.0 in 2001 to HyperTransport 3.0 in 2008, the maximum clock
speed and transfer rate increased from 800 MHz (1.6 MT/s
(4.8 GT/s) in each direction. This gives each HyperTransport 3.0 link a maximum data rate of
4.8 GT/s × 2 bytes per transfer, or 9.6 GB/s (19.2 GB/s aggregate data rate).
Figure 1. The HyperTransport interconnect separates memory and I/O traffic and directly attaches memory to
each processor, allowing memory capacity to scale with the number of processors.
HyperTransport Technology was invented at AMD with contributions from industry partners and is managed and licensed by the
HyperTransport Technology Consortium, a Texas non-profit corporation.
MT/s, or megatransfers per second, equals the speed of the link in millions of cycles per second times the number of transfers per cycle.
Compared to a shared, parallel front-side bus,
) to a maximum of 2.4 GHz