PCI Shared Bus Technology
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PCI uses a shared bus technology which allows communication among the different devices on the bus; the different PCI devices, such as the network card, a sound card, RAID card etc., are all attached to the same bus through which they communicate with the CPU, and there is an arbitration scheme in place for deciding which device gets access to the bus when (Stokes). The advantages of this arrangement are that it is simple, cheap and easy to implement. However, the more devices attached, the more noise on the bus and the harder it is to get a clear signal through. PCI-X doubled the bandwidth and therefore the data transmission capability. PCI Express, the newest technology, has point-to-point bus topology, with a shared switch replacing the shared bus, and the switch routes the traffic between devices. By centralizing traffic routing and resource-management functions, PCI Express allows improved quality of service. PCI Express is the new I/O technology from Intel Corporation which was designed to replace the Peripheral Component Interconnect expansion bus in PCs and servers, and to eliminate I/O bottlenecks when using video graphics, 10Gbit/sec and other devices (Mitchell)). The first PCI Express motherbpards and chip sets were released last summer and the system was available last August. A few adapters are now also available. The system was developed through the PCI Special Interest Group, and PCI Express, also known as PCIe, replaces the PCI bus with a serial arc
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strict (Stokes). Because the bus is wider, it consists of more wires, which leads to more noise from crosstalk, and because all the wires are connected to multiple PCI devices at their endpoints, placing an even larger load on the bus and even more noise. Also, the PCI devices themselves need 32 extra pins, increasing the manufacturing cost of each individual device and of the connectors and motherboards.
PCI Express has already been used to replace the accelerated graphics port for high-end graphics on PCs (Mitchell). PCI Express is considered overkill for most other I/O needs. Early PCI Express adapters on servers focus on technologies which will most likely max out the current 1GB/sec. PCI-X bus, and this includes Gigabit Ethernet, RAID controllers and Fibre Channel, but as long as PCI-X is not a bottleneck problem, this is still the preferable solution because it has bee proven over time to be successful. PCI-SIG is working on a server I/O module specification that is described by the group's chairman, Tony Pierce, as "an external, hot-pluggable form factor designed specifically for servers" and a revised specification with double the data rate was due out in 2005. The transition to PCI Express slots will begin slo
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Some common words found in the essay are:
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Approximate Word count = 1249
Approximate Pages = 5 (250 words per page)
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