Technology and architecture of HP ProLiant AMD-based 100 - series G6 (Generation 6) servers

Figure 1. Block diagram of Direct Connect 2.0 architecture in the AMD 2400-series processors
HyperTransport technology
HyperTransport is a point-to-point interconnect with two unidirectional links (see Figure 2) that is
designed to connect the processors directly and to connect each processor to its dedicated memory
banks, as well as to other I/O chipsets.
2
Compared to a shared, parallel front-side bus,
HyperTransport has the advantages of having no overhead for bus arbitration and easier signal
integrity maintenance, which results 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 (HT1) in 2001 to HyperTransport 3.0 in 2008, the maximum clock
speed and transfer rate increased from 800 MHz (1.6 MT/s
3
) to a maximum of 2.6 GHz (5.2 GT/s)
in each direction.
2
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.
3
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.
3