System information

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Altos R380 F2 FAQ (Frequently Asked Questions)
17. PCI & PCI-Express
1. Does Altos R380 F2 support PCI-Express Gen 3?
ANSWER:
ANSWER:ANSWER:
ANSWER: Yes.
2. Does Altos R380 F2 support PCI Express Base Spec 3.0?
http://www.pcisig.com/specifications/pciexpress/
ANSWER:
ANSWER:ANSWER:
ANSWER: Yes.
3. Is PCI-Express 3.0 backward compatible with PCI-Express 2.x and 1.x?
ANSWER:
ANSWER:ANSWER:
ANSWER: Yes.
4. What is the bit rate for PCIe 3.0 and how does it compare to prior generations of PCIe?
ANSWER:
ANSWER:ANSWER:
ANSWER: The bit rate for PCIe 3.0 is 8GT/s. This bit rate represents the most optimum tradeoff between
manufacturability, cost, power and compatibility.
The PCI-SIG analysis covered multiple topologies and configurations, including servers. All of these studies
confirmed the feasibility of 8GT/s signaling with low-cost enablers and with minimal increases in power, silicon
die size and complexity.
5. How does the PCIe 3.0 8GT/s “double” the PCIe 2.0 5GT/s bit rate?
ANSWER:
ANSWER:ANSWER:
ANSWER: The PCIe 2.0 bit rate is specified at 5GT/s, but with the 20 percent performance overhead of the
8b/10b encoding scheme, the delivered bandwidth is actually 4Gbps. PCIe 3.0 removes the requirement for
8b/10b encoding and uses a more efficient 128b/130b encoding scheme instead. By removing this overhead,
the interconnect bandwidth can be doubled to 8Gbps with the implementation of the PCIe 3.0 specification.
This bandwidth is the same as an interconnect running at 10GT/s with the 8b/10b encoding overhead. In this
way, the PCIe 3.0 specifications deliver the same effective bandwidth, but without the prohibitive penalties
associated with 10GT/s signaling, such as PHY design complexity and increased silicon die size and power. The
following table summarizes the bit rate and approximate bandwidths for the various generations of the PCIe
architecture:
PCIe architecture
PCIe architecturePCIe architecture
PCIe architecture Raw bit rate
Raw bit rateRaw bit rate
Raw bit rate
Interconnect
Interconnect Interconnect
Interconnect
bandwidth
bandwidthbandwidth
bandwidth
Bandwidth p
Bandwidth pBandwidth p
Bandwidth per
er er
er
lane per direction
lane per directionlane per direction
lane per direction
Total bandwidth
Total bandwidth Total bandwidth
Total bandwidth
for x16 lnk
for x16 lnkfor x16 lnk
for x16 lnk
PCIe 1.x 2.5GT/s 2Gbps ~250MB/s ~8GB/s
PCIe 2.x 5.0GT/s 4Gbps ~500MB/s ~16GB/s
PCIe 3.0 8.0GT/s 8Gbps ~1GB/s ~32GB/s
6. Where could I find more information about PCI-Express 3.0?
ANSWER:
ANSWER:ANSWER:
ANSWER: Please go to PCISIG web site.
http://www.pcisig.com/specifications/pciexpress/
7. Is PCI-Express compatible with PCI or PCI-X?
ANSWER:
ANSWER:ANSWER:
ANSWER: No. PCI-Express is a different technology. PCI-Express adapters cannot be installed on PCI or PCI-X
slots. PCI or PCI-X adapters cannot be installed on PCI-Express slots.
8. Does Altos R380 F2 support PCI-X?