Overview of PCI-express bus standard from 1.0 to 3.0

PCI-Express is the latest bus and interface standard. Its original name is "I/O", which was proposed by Intel, obviously, Intel stands for the next generation of I/O interface standards. Changed to "PCI-Express" only after being certified by the PCI-SIG (pCI special interest organization ". This new standard will completely replace the current PCI and AGP, and ultimately achieve unified bus standards. Its main advantage is its high data transmission rate, which can reach a maximum of 10 Gb/s at present, and has considerable development potential. PCI Express also has multiple specifications, from PCI Express 1x to PCI Express 16x, which can meet the needs of low-speed devices and high-speed devices that may appear at present and in the future. Intel i915 and i925 series chipsets support PCI Express. Of course, a long process is also required to fully replace PCI and AGP. Just like PCI replacing Isa, there will be a transitional process.

PCI Express (hereinafter referred to as PCI-E) uses the current industry's popular point-to-point serial connection, compared to PCI and more early computer bus shared parallel architecture, each device has its own dedicated connection, you do not need to request bandwidth from the entire bus, and you can increase the data transmission rate to a high frequency to achieve the high bandwidth that PCI cannot provide. Compared with the traditional PCI bus, only one-way transmission can be implemented in a single time period, the dual-ticket connection of PCI-E can provide higher transmission rate and quality, and the difference between them is similar to that of half-duplex and full-duplex.

PCI-E interfaces vary based on bus bit width, including X1, X4, X8, and x16, while X2 mode will be used for internal interfaces instead of Slot Mode. The PCI-E specification is connected from one channel to 32 channel connections, with very strong scalability to meet different system equipment for different data transmission bandwidth needs. In addition, the shorter PCI-E card can be inserted into a longer PCI-E slot for use, the PCI-E interface can also support hot plugging, which is not small leap. The 250 Mb/s transmission speed of PCI-E X1 can meet the requirements of mainstream sound effect chip, Nic chip and storage equipment for data transmission bandwidth, however, it is far from able to meet the data transmission bandwidth requirements of graphics chips. Therefore, the PCI-E interface used to replace the AGP interface is x16 in width and can provide 8 Gbit/s bandwidth, far exceeding the 2.1 Gbit/s bandwidth of the AGP 8x.

Although the PCI-E specifications allow for x1 (250 Mbit/s), X2, X4, X8, X12, x16, and x32 channel specifications, as currently, PCI-E X1 and PCI-E x16 has become the mainstream specification of PCI-E, while many chipset manufacturers in the south bridge chip to add support for PCI-E X1, in the North Bridge Chip to add support for PCI-E x16. In addition to providing extremely high data transmission bandwidth, since the PCI-E transmits data in a serial packet mode, each pin of the PCI-E interface can obtain more bandwidth than the traditional I/O standard, this can reduce the production cost and volume of PCI-E equipment. In addition, the PCI-E also supports High-Order Power Management, supports hot swapping, supports synchronous data transmission, bandwidth optimization for priority transmission data.

PCI-E 1.0 specifications:

PCI-E 1x (1.0 standard) using one-way 2G baud rate for transmission, because each word segment is 10 bits (one start bits, eight bits, one second bits ), therefore, the transmission rate is 2.5g/10 = 250 Mb/s (250 MB per second), it can be calculated that the one-way transmission rate of PCI-E 16 X is 250 MB/S * 16 = 4 Gb/s, the bidirectional transmission rate is 8 Gb/s. Currently p43 below motherboard (excluding p43) adopts PCI-E 16x (1.0 standard), PCIe-104 express and PCIe-104 adopts PCI-E 1.0 specification.

PCI-E 2.0 specifications:

PCI-E 1x (2.0 standard) uses a one-way 5g baud rate for transmission, because each word segment is 10 bits (one start bits, eight bits, one second bits ), therefore, the unidirectional transmission rate is 5g/10 = 500 Mb/s (500 mb per second), which can calculate the PCI-E 16x(2.0 standard) the one-way transmission rate is 500 Mb/s * 16 = 8 Gb/s, the two-way transmission rate is 16 Gb/s, The PCI-E 32x (2.0 standard) speed is 32 Gb/s, p43, P45, p55 and above motherboard With PCI-E 16x (2.0 standard) slot

PCI-E 3.0 specifications:

PCI-E 1x (3.0 standard) uses a one-way 10g baud rate for transmission, because each word segment is 10 bits (1 start bits, 8 bits, 1 percentile bits ), so the one-way transmission rate is 10g/10 = 1000 Mb/s (1000 MB per second), which can calculate the PCI-E 16x(3.0 standard) the one-way transmission rate is 1000 Mb/s * 16 = 16 Gb/s, the two-way transmission rate is 32 Gb/s, the two-way transmission rate of PCI-E 32x (3.0 standard) is as high as 64 Gb/s, this specification will be officially released in 2010.

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Overview of PCI-express bus standard from 1.0 to 3.0