4) PCI-X Bus

The PCI-X interface is the updated version of the connected PCI Bus (peripheral components Interconnect), still using the traditional bus technology, just there are a lot of other number of wiring pins, at the same time, as mentioned above, all the connected devices share all available bandwidths.

 

1 What is the PCI-X and the original PCI interface is different: a change to the past 32-bit, PCI-X swap with 64-Bit Width to transmit data, so the bandwidth of their own initiative to multiply twice, the length of the expansion slot will inevitably increase. In addition, the rest include the communication protocols, signals, and standard connector formats, the advantage is that the 3.3 volt 32-bit PCI adapter can be used in the PCI-X expansion slot, of course, if you want to, can also be connected to the 64-bit PCI-X adapter on the 32-bit PCI expansion slot,, the bandwidth speed will be greatly reduced. The improved version number of this bus doubling applies to some specialized storage controllers, such as SCSI, iSCSI, fiber channel, 10gbit Ethernet, and InfiniBand, still unable to provide enough bandwidth, So introduce the PCI-SIG (Special Interest Group) interface to provide several different speed levels that are able from PCI-X 66 (rev. 1.0b) all the way to PCI-X 533 (rev. 2.0) specifications, the following table of these technical details: bus width frequency speed function bandwidth PCI-X 66 64-bit 66 MHz hot ging Ging, 3.3 V 533 MB/spci-x 133 64-bit 133 MHz hot ging Ging, 3.3 V 1.06 GB/spci-x 266 64-bit/16-bit options 133 mhzdouble data rate hot plugging, 3.3 & 1.5 V, ECC supporte D 2.13 GB/spci-x 533 64/16-bit option 133 mhzquad data rate hot ging Ging, 3.3 & 1.5 V, ECC supported 4.26gb you can see that when the frequency speed reaches 13 3 MHz of PCI-X 133, in order to multiply the bandwidth, the technology of the primary storage and the front-end bus is not enough. Therefore, PCI-X 266 uses double data rate technology, so that every rise and fall of the clock pulse edge can be data transmission, so there is a more than doubled the opportunity to data transmission, while the PCI-X 533 specification goes further by using the technology that uses every clock pulse capable of delivering four (quad data rate), Intel uses these technologies as early as the front-end bus of all Pentium 4 and Xeon processors.

 

2via PCI-X bus structure interpretation when the industry standard ISA and VLB bus has gradually become one of the important reasons for limiting system performance, because ISA (Industry Standard Architecture) the bus can only provide 5-8 Mb/s bandwidth, so the new bus architecture of PCI (Peripheral Component Interconnect) is published. PCI is a 32bit bus architecture that works at 33 MHz, at the same time, the 64bit/66 MHz solution is also available. For peripherals with high bandwidth requirements, such as SCSI raid, PCI is proposed as a timely rain. Later, PCI began to become the mainstream architecture, but some years later, new problems emerged. When server and high-end PC users once again find that the 533 Mb/s bandwidth provided by the 64bit/66 MHz PCI bus is still insufficient, this requires the industry to announce a new bus architecture. PCI-X, an extended architecture of the PCI bus, is now known as PCI-X. This year officially announced the 1.0 specification, so some manufacturers began to add support for PCI-X in their design, we are expected to see the fourth quarter of this year, based on the PCI-X bus products listed. What is the improvement in the bandwidth of PCI-X compared to the PCI 2.2 specification? The following is a detailed description of PCI-X. Performance unlike the PCI bus, the PCI bus must frequently exchange data between the target device and the bus, while the PCI-X agrees that the target device is only visible to a single PCI-X device for exchange, at the same time, assuming that the PCI-X device does not transmit any data, the bus proactively removes the PCI-X device to reduce the wait cycle between PCI devices. Therefore, at the same frequency, the PCI-X will be able to provide 14-35% higher performance than PCI. [64bit/66 MHz] Another advantage of the bus frequency PCI-X is that it has a scalable frequency, that is, the frequency of the PCI-X will not be as fixed as PCI, it can change with the change of the device. For example, if a device works at 66 MHz, it will work at 66 MHz. If the device supports MHz, the PCI-X will work at MHz. PCI-X can support 66,100,133 MHz of these frequencies, and in the future, may provide many other frequencies. [66 MHz PCI-X] A PCI-X controller working at 66mhz will be able to hack up to 4 PCI-X devices, of course, assuming that a bridge chip that adds a PCI-X to a PCI-X can support many other devices. The 66 MHz PCI-X has a bandwidth of 533 Mb/s [100 MHz PCI-X] All PCI-X devices are working at MHz, at which point the PCI-X bus will be able to manage up to two PCI-X devices, with 64bit bus and 800 MHz frequency, with 133 Mbit/s of bandwidth [MHz PCI-X] The most luxurious version of The PCI-X, the PCI-X working at 133mhz will be able to provide an astonishing 1066 Mbit/s band width, of course, at this time only one PCI-X device works. But for some devices that require a lot of bandwidth, such as fiber interfaces, Gigabit Ethernet interfaces, etc., PCI-X 133 will be able to improve a lot of advantages.