The new G5 powered Macs are smokini, but it is not just because of the IBM made processors that the aluminum-clad Macs are fast; a lot of work went into designing the computeris system architecture so that data moving from processor to memory to other chips do so as quickly as possible. Speed up the bus that handles the data transport, and you speed up the computer. To get at least some of the speed it needs, Apple currently uses a HyperTransport bus to connect heavily used subsystems like the controllers for the hard drives, the Gigabit Ethernet card, and FireWire, in the G5 Power Mac.
Whatis HyperTransport? From HyperTransport.org:
HyperTransport universal chip-to-chip communications technology is an advanced high-speed, high-performance, point-to-point link for integrated circuits. HyperTransport provides a universal connection that is designed to reduce the number of buses within the system, provide a high-performance link for embedded applications, and enable highly scalable multiprocessing systems. Originally designed to optimize high performance personal computers, it has been extended by the HyperTransport Consortium to provide significant benefits to desktop and mobile personal computers, networking equipment, servers, consumer products and embedded applications.
Apple and other computer industry heavyweights, like Sun, AMD, IBM, and Cisco, are members of the non-profit Hypertransport Consortium, a group dedicated to, "...promoting HyperTransport technology as an open, freely available industry specification for high bandwidth chip-to-chip communications."
C|Net is reporting the The HyperTransport Consortium will announce a specification for a new, faster HyperTransport architecture that will enable computers to boost inter-chip data rates to a blistering theoretical limit of 40 gigabytes per second. Hereis more details from the C|Net article, New standard to speed chip connections:
The HyperTransport Consortium, which controls the specifications for the chip-to-chip connection technology behind Advanced Micro Devicesi upcoming Opteron processor, expects to release the new specification, HyperTransport 2.0, a year from now. HyperTransport is an effort initiated by AMD to define a new high-speed technology for connecting PC components.
HyperTransport 2.0 will provide data transfers between chips at 20 gigabytes to 40 gigabytes per second, depending on the system architecture. Such speeds will greatly increase the performance and versatility of servers or desktops, said Gabriele Sartori, president of the consortium and director of strategic alliances at AMD.
The 2.0 specification will come out late this year or early next year, he (Sartori) added. The 2.0 version will provide 3 gigabits to 5 gigabits per second for each pair of pins, the electrical contacts that physically transfer data. Assuming a rate of 5 gigabits per second, a 16-bit HyperTransport link--incorporated onto a microprocessor or other chip--would provide data transfer rates of 20 gigabytes per second, while a 32-bit link will switch data at 40 gigabytes. Current HyperTransport links exchange data at 1,600mbps per pin pair, topping out at 12.8 gigabytes for 32-bit devices.
C|Net is also reporting that HyperTransport 1.0.5, un update to the current technology, has been announced. Stop by C|Net for the full article. For more information about HyperTransport, stop by the HyperTransport Consortium Web site.