HP ProLiant 300-series AMD-based G6 server technology

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 (Figure 2). It directly
connects the processors to each other and connects 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 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 (4.8 GT/s)
in each direction. This gives each HyperTransport 3.0 (HT3) link a maximum data rate of
4.8 GT/s × 2 bytes per transfer, or 9.6 GB/s.
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.
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