PCI, PCI-X, PCI-E and PCI 2.2 again

PCI: Peripheral Component Interconect.

//===

• PCI-X可能可以向下相容33MHz PCI32的界面卡 ...　
  PCI-X是3.3V的,早期的33MHz/PCI32的卡需要5V
• PCI-E跟PCI-X/PCI是不相容的？？？
• PCI的插槽長度約 8.5 cm
• PCI-X的插槽長度最長
• 將PCI 64-bit 介面卡安裝到 PCI 32-bit 的插槽內　還能正常運作
• 反之未必？
• 32-Bit/66MHz PCI 2.2 介面卡 可工作於66MHz或33MHz,　
• 支援66MHz其電壓必定要工作在3.3V.
• 新的PCI 64bit　一般支援3.3V
• "插不進去別硬插就是"

//===　傳統的PCI
"...
* PCI 1.0, which was merely a component-level specification, was released on June 22, 1992.
* PCI 2.0, which was the first to establish standards for the connector and motherboard slot, was released on April 30, 1993.
* PCI 2.1, released on June 1, 1995, allows for 66 MHz signaling at 3.3 volt signal voltage (peak transfer rate of 533MB/s), but at 33 MHz both 5 volt and 3.3 volt signal voltages are still allowed. It also added transaction latency limits to the specification.
* PCI 2.2 Power rails to provide 3.3 volt supply voltage are now mandatory.

* PCI 2.3 permits use of 3.3 volt and universal keying, but does not allow 5 volt keyed add in cards.

# PCI 3.0 is the final official standard of the bus, completely removing 5-volt capability.
# Mini PCI is a form factor of PCI 2.2 for use mainly inside laptops
# CardBus is a PC card form factor for 32-bit, 33 MHz PCI
# CompactPCI uses Eurocard-sized modules plugged into a PCI backplane.
# PC/104-Plus is an industrial bus that uses the PCI signal lines with different connectors.

..."




//=== nVidia nforce3

"... Integrates a fast PCI-to-PCI bridge running at 33 MHz. It includes an arbiter that supports six external master PCI slots. Features of the PCI interface include:

• PCI 2.3-compliant, 5 V tolerant???
• Supports six external PCI slots at 33 MHz
• Supports six bus master arbitration
• PCI master and slave interfaces
• Supports both master-initiated and slave-initiated terminations
• Bidirectional write posting support for concurrency
• Flexible routing of all four PCI interrupts
• Supports read ahead: memory read line (MRL) and memory read multiple (MRM)

..."


[ref]
http://en.wikipedia.org/wiki/Conventional_PCI#Card_keying
http://www.nvidia.com/page/pg_20030918437537.html
http://www.pczone.com.tw/vbb3/thread/14/125494/
http://www.pcgamma.com/showthread.php?t=5274
http://blog.sina.com.tw/kio_orz/article.php?pbgid=30830&entryid=596632
http://en.wikipedia.org/wiki/File:PCI_Keying.png