Talk:Peripheral Component Interconnect

5V PCI cards

Does anyone have a picture of a 5V PCI card? These must be quite rare. I assume they won't work in modern boards? Drutt (talk) 06:57, 5 June 2009 (UTC)

I have this back-to-front: it's 3.3V cards that seem to be rare (these have the notch on the side nearest the backplate). This standard is also newer than the 5V one. Drutt (talk) 07:05, 5 June 2009 (UTC)

Both 5V and universal (dual notch) cards are common, I don't think i've ever seen a 3.3V only card, it would be an niche market if it did exist since it wouldn't be compatibile with the vast majority of machines. I've only seen a 3.3V 32 bit slot once (on a mips devboard), 3.3V 64 bit slots are quite common because of the higher speeds possible (66 mhz PCI and higher PCI-X). Plugwash (talk) 00:52, 7 June 2009 (UTC)

I have a board here with two 3.3V PCI-X slots, two 5V PCI-X slots and two 5V PCI slots. However, the two 3.3V slots have removable notches which can be moved to the 5V position to enable the slot to take 5V cards as well. Strange arrangement. Danceswithzerglings (talk)

very strange since unless those removable notches are some clever electrical device there is afaict no way for a motherboard to detect the voltage of a card. Of course the manufacturer may be just assuming that even cards notched for 5V can in fact cope with 3.3V. Plugwash (talk) 11:15, 1 October 2009 (UTC)

Power ratings ?

Can someone please provide the power ratings for PCI slots ? Thanks ! --Xerces8 (talk) 07:18, 24 April 2009 (UTC)

From the PCI specification 3.0, section 4.3.4.1 (Power Requirements):

• No limit on 3.3 or 5 V rails except for 25 W per card total. (That's 7.6A on 3.3V or 5A on 5V.)
• At most 0.5 A from the +12 V rail
• At most 0.1 A from the −12 V rail

Systems may impose lower limits on the 3.3V and 5V rails. It is recommended that cards use at most 10 W at boot time, and enable higher-power modes only when the device is in use. See also section 4.4.2 (Power Supply).

71.41.210.146 (talk) 09:30, 16 July 2009 (UTC)

Compatible ?

I see in the article that "PCI-X adapters and slots are backward-compatible with 32-bit PCI slots and adapters". Does this mean all PCI-X adapters will work in a PCI slot (at reduced speed obviously on the 32 bit bus)?

If the card supports the boards voltage (most will) and there isn't anything blocking the overhanging connector then it should work fine. 130.88.108.187 (talk) 13:13, 9 October 2009 (UTC)

Comments on PCI protocol sections recently added to article

This is a discussion area for beating the above sections into shape for inclusion in the article. NOTE that as concerns here are addressed, the text above will change and so the comments might be out of date. (The inclusion has since happened; the sections have been moved into the main article.)

Comments by User:JMiall (talk)

• This was a solicited review of the section.
  • Interleaved responses by User:71.41.210.146 (talk)

(please post these to the talkpage there if you wish):

• You asked first of all if it read well to someone unfamiliar with the specs. I think that basically it does.
• I'm a bit worried though that there is too much detail, I'm not sure where is a good place to draw the line though. Possibly all this information should be split off to (an)other article(s) and summarised within this one?
  • Perhaps. Creating new articles is a pain for me, so maybe I'll leave that to someone else.
• I've not looked at everything you have put on the talkpage yet, I'll come back with some more comments if you found these useful.

Specific questions/issues to be going on with:

• Why is "asserted" in quotes?
  • That was for emphasis, because that was where asserted was defined. Should be italics, thanks.
• 'controlled by 5 main control signals' etc - is signal the right word here? ie are FRAME# etc the name of a particular line or the signals that are present on that line?
  • Yes, they are physical wires. You can see them in Conventional PCI#Connector pinout. (E.g. FRAME# is 34A.) Er... what is the distinction between "line" and "signal" you're making here? Generally, I think of them as synonymous, except that "signal" emphasizes information-carrying capacity. "+5V supply line", but "clock signal". I suppose that "signal" is more abstract, and e.g. two signals could be multiplexed onto the same wire...
• Also the when the lines/signals are mentioned they sometimes are put in brackets, sometimes commas and sometimes nothing.
  • I don't understand this one. [brackets]? Or (parentheses)? Can you give me an example?
• 'will remain high' - add 'voltage', also voltage needs linking in the main article
  • H'm... probably.
• 'each bus line be undriven' - given the potential for confusion for someone not too familiar with English is it possible to reword?
  • Okay. I tried to clarify.
• Link Pull-up resistor
  • Good point. Sorry.
• 'Signals nominally change on the falling edge of the clock' - should this be 'nominally' or 'normally'? Is the spec not specific about precisely when they should change?
  • Nominally, and no the spec is not. To be precise, they must change within a specific time window relative to the leading edge of the clock, so the signal has time to arrive at the receiver. This window is close to the falling edge of the clock, and I felt that the details of setup and hold times and clock jitter was definitely something that didn't below in Wikipedia; see the spec if you care about that level of detail.
• The wording rather implies at that all the PCI devices are concious intelligent beings. It is probably worth toning this down a bit. ie 'decides', 'promise', 'generally attempt', 'desire'
  • H'm... this is because the actual function of the PCI device is not relevant here and the reason why it "wants to talk" to the PCI bus is not discussed. The language sort of follows naturally from that. I can try a bit, e.g. promise can be changed to "guarantee," but does anything particularly grate?
• '(There are rules for how it is supposed to behave, but they will be mysterious to any single device.)' - is this necessary?
  • In the middle of emphasizing that the GNT# signal might go away at any time for no obvious reason, it occurred to me that that isn't the same as no reason at all.
• link 'bus master'?
• 'but may not start one unless it observes GNT# asserted the cycle before it begins a transaction' - unclear 'it's
• 'so there are actually three signals' - fairly colloqial language
• 'Actually, it has 2.5 cycles' - 'they' not 'it'?
  • Perhaps "each target".
• 'On the fifth cycle...' - I'm unsure what this paragraph means.
  • Okay, I'll work on it. See the figure below with numbered
• 'Access to PCI configuration space is a special case' - of what?
  • Of address decoding; many address bits are ignored, and IDSEL matters. Thanks, I'll tweak it.
• 'enables' - link or explain?
  • Don't the following sentences do it adequately?
• 'In case of a write' - missing 'the'
• 'more purely'?
  • Arrgh.
• Several times you use 'read' or 'write' when it would probably be clearer to use 'read signal' or something similar
  • I can't find an example. Can you point one out?
• 'line turns around during' - what does turns around mean here?
  • This is the undriven cycle discussed above. I expanded that section, because it becomes important later.

Main article:

• 'However, they are not wired in parallel as are the other traces' - this needs explaining. Traces have not been mentioned yet and it is unclear what this means any way due to the 'are not...as are...'
  • Thanks, will fix.

JMiall₰ 23:16, 2 August 2009 (UTC)

• 71.41.210.146 (talk) 01:44, 3 August 2009 (UTC)

Conventional PCI vs. PCI Local Bus

The lead says "Conventional PCI (part of the PCI Local Bus standard...)". My questions are:

• Is Conventional PCI an industry term or just something made up by Wikipedians to distinguish the original PCI from newer versions (PC-X, PCIe).
• If Conventional PCI is part of the PCI Local Bus standard, what else is in that standard? --Kvng (talk) 21:47, 1 September 2010 (UTC)

OFFICE action

The following were removed as a result of a DMCA takedown notice, per the office action policy. Please do not readd these. The article remains open for editing, with the exception of any links to these specifications. If you'd like to appeal, please email your notice to me at philippewikimedia.org.

PCI Local Bus Specification, Revision 2.1

PCI Local Bus Specification, Revision 2.2

PCI Local Bus Specification, Revision 3.0

Office actions may not be reversed except through the Wikimedia Foundation office. The pertinent policy lives at WP:OFFICE. Philippe Beaudette, Wikimedia Foundation (talk) 01:42, 4 January 2011 (UTC)

This is quite pointless because you can still see it in the article history. --Hinata talk 15:46, 21 January 2011 (UTC)

Seconding the previous' posters finding. Also, are you <censored by myself>? The original Document is still online, publicly available and a top hit on google. I bet this DMCA Notice was automatically generated. Furthermore, completely removing the reference is just stupid - wouldn't it suffice to just remove the link? Effin' lawyers.. --Roeme (talk) 11:12, 23 January 2011 (UTC)

Since PCIe is quickly replacing Conventional PCI, and PCI-SIG should release the Conventional PCI spec for a reasonable price to non-members. • Sbmeirow • Talk • 15:15, 23 January 2011 (UTC)

For those who are interested, I've posted the DMCA take-down notice at this location on the Foundation's wiki. It specifically mentions the reference section and requires that we remove the specifications. At this point, until or unless we receive a DMCA counter-notice, those standards can not be reposted. If we were to allow that to happen, we threaten the immunity under which we operate through the Safe Harbor provisions of the Digital Millenium Copyright Act. I'd be happy to provide someone with instructions regarding where to send a counter-notice if someone has a valid couter-claim, but be aware that it would be a statement under penalty of perjury that you have a valid copyright counter-claim. Philippe Beaudette, Wikimedia Foundation (talk) 01:24, 24 January 2011 (UTC)

Don't you see that the one writing this notice didn't understand that it's not wikipedia that's hosting that PDF?! From my understanding of this notice and the DMCA in general, it would be completely okay to CITE the specification - without linking to it. Someone readded the reference in the mean time (even with a link to the pci sig), so further discussion is moot. Next time, I'd recommend just to break/remove the link. Removing the ref alltogether in my opionion is just excessive and feels like censorship. --Roeme (talk) 10:07, 24 January 2011 (UTC)

I will execute a DMCA take-down exactly as instructed by legal. Anything else compromises our position. Your understanding may or may not be correct, but I will not follow your interpretation - I am duty bound to follow the interpretation of our legal team. Philippe Beaudette, Wikimedia Foundation (talk) 02:08, 25 January 2011 (UTC)

Roeme, see Wikipedia:OFFICE#DMCA_compliance, particularly "the Foundation is required to comply with validly formulated notices even if they are spurious". I'm not saying this one is spurious. The point is that the Foundation complies to keep its safe-harbor status, not because it has independently assessed the merits of the claim (although they may do that anyway).--Chaser (talk) 01:57, 1 February 2011 (UTC)

Well this kinda depends. It can be argued that linking to copyrighted material in this way is not a copyright violation, and thus usage of DMCA for this purpose (getting a website to remove a link) is abuse of the DMCA system. The question of linking to copyrighted material is FAR from settled. While what the foundation is doing, is acting on the safe side, it is (as with the caving in to another user who didn't understand copyright [alexander liptek]) a dangerious precedent that we should keep a close eye on. I don't want to arrive at a place where the foundation always acts on the safe side, and leaving this battles of DMCA abuse entirely to its editors. 93.111.234.204 (talk) 16:51, 1 February 2011 (UTC)