Talk:Bus (computing)

message: Does nobody else see the striking resemblance of the main article photo (https://en.wikipedia.org/wiki/Bus_%28computing%29#/media/File:PCIExpress.jpg) to an actual school bus?
I bring this up because at first glance, I thought I had navigated to the wrong wiki page and was about to hit the back button when I looked closer and realized that this was a photo of yellow card slots with capacitors as wheels.  I might suggest another photo is used as the landing image as silly as it sounds.  — Preceding unsigned comment added by 130.76.24.16 (talk) 22:19, 25 April 2017 (UTC)
thread_title:  main article picture 

message: Question about definition of bus width.  Is it just the bandwidth of the bus times the duration of a CPU cycle?  It would be nice if that were defined so I'd know for sure.
The "bus width" is the number of data bits that can be simultaneously transferred.
Usually that is identical to the number of data wires in the bus -- i.e., the number of wires in the data bus.
The memory bus to a typical memory chip includes 8 wires in the data bus, 15 wires in the address bus, and 3 wires in the control bus, giving a 8 bit bus width.
The various serial buses transmit 1 bit at a time, so they have a bus width of 1 bit (no matter if they transmit that bit on a single-ended wire, or differentially on 2 wires, and no matter whether or not there are other control wires associated with it).
--75.19.73.101 23:18, 11 November 2007 (UTC)
thread_title:  bus width 

message: Is RS-232 a bus? Surely, it is not, it is strictly point-to-point and hence not a bus in any sense. The same goes for RS-422 and probably a few others too -- Egil
: A bus should connect more than two elements. I agree that RS 232 is not reasonably a "bus" and is never described as such in the EIA standard (at least the Rev C that I have).  I'm taking it out. --Wtshymanski 15:57, 15 Apr 2005 (UTC)
replies: text: RS-422 is a bus. Serial Attached SCSI is not a bus (as mistakenly stated in the article). It is easier to understand topologies reading Network topology.  — Preceding unsigned comment added by 185.57.28.108 (talk) 14:30, 1 April 2017 (UTC)
thread_title:  RS-232 

message: Hello! I'm a newbie here and as I didn't find anything in Wikipedia about the controller area network (CAN) bus, I intended to create its entry. But I'm not sure if I should add a link to it in the Computer bus page or in the Electrical bus page. What do you suggest?
By the way, to have an idea about what is the CAN bus, look at: http://www.pcwebopedia.com/TERM/C/controller_area_network.html.
Thanks. -- Akira - Cleber Akira Nakandakare
:An article about CAN (controller area network) is a very welcome contribution. It definitely think it should be listed on the Computer bus page, under  Examples of External Computer Buses, Serial -- Egil 07:06 21 May 2003 (UTC)
:: done. --75.19.73.101 23:18, 11 November 2007 (UTC)
thread_title:  CAN bus 

message: I think that the view of RS-232 not being a bus is conceptual, as someone else suggested about CAT5 nework connections.  As a specific example, Centronics parallel connections are supposedly point-to-point, but parallel scanners and parallel ZIP drives (not to menion SCSI-via-parallel and IDE-via-parallel) have been out for years, which can daisy-chain between the computer and a printer.  There are multiplexers available to run several independent signals over a serial connection; these are litle different from USB hubs and the like. Scott McNay 01:43, 2004 Feb 26 (UTC)
: The PC-compatible world is full of stunts like that, but desparate work-arounds and expediencies in my opinion don't qualify the IBM PC parallel port as a "bus". It wasn't intended to be used as such, shucks, it wasn't even bidirectional till late in its evolution.  --Wtshymanski 16:27, 15 Apr 2005 (UTC)
thread_title:  RS-232 

message: The following was on the main page in a hidden (html) comment:
This is not a technical encyclopedia; this is a general-purpose encyclopedia.  Thus, I think we should make an effort to make things understandable by non-techs, if possible, without sacrificing correctness or details.
copied across and removed from article page by VampWillow 20:51, 12 Jun 2004 (UTC)
replies: text: A diagram is in order. I'll put it on my to-do list unless someone beats me to it. --Wtshymanski 16:27, 15 Apr 2005 (UTC)
thread_title:  readability 

message: The article says "All the equipment on the bus has to talk at the same speed, and thus shares a single clock." Surely this isn't true, since, for example the Motorola 68000 family implmeented asynchronous buses, where data transfer would vary in speed depending on how fast a peripheral chose to assert the "DTACK" (data transfer acknowledge) signal. --Wtshymanski 16:16, 15 Apr 2005 (UTC)
thread_title: Asynchronous vs synchronous buses

message: RCA Spectra machines did not run Multics...multics was in the GE and the Honeywell camp. Spectra was a pseudo IBM compatible system running operating systems TOS, TDOS and TSOS. I suspect the comments about the BUS could be correct...but for Spectra machines of those that ran Multics?
tg
I agree.  But with either answer, it would probably not be the first such system.  I don't know what the first would be, but I would guess that Burroughs D825 would be an early example. http://research.microsoft.com/~gbell/Computer_Structures__Readings_and_Examples/00000280.htm
Perhaps this is too obscure to be illustrative. DHR 23:40, 19 February 2006 (UTC)
thread_title:  Spectra and Multics 

message: Do you guys think it'd be worth mentioning the three-bus architecture? As I understand it, it's an important model and is used a lot in computer systems. I could write a little about it if it's a good idea. Haddock420 12:33, 13 January 2006 (UTC)
replies: text: Yes, please write about it. Are you talking about the 3 buses in a system bus architecture, or some other three-bus architecture? --DavidCary (talk) 16:34, 11 March 2014 (UTC)
thread_title:  Three Bus Structure 

message: As nobody really calls the subject of this article a "computer bus" (do they?) I propose a name change, to "Bus (computing)" to fit in better with standard Wikipedia naming.  Any comments? JulesH 09:50, 13 December 2006 (UTC)
replies: text: Ah, it seems expansion bus redirects to expansion card, which is somewhat a different topic. This topic is the architectural concept, which might be implemented in a number of different physical ways. One common way is to have cards that plug in, often some time after the other parts of the computer are assembled, which is what that article describes. There are many other computer buses that are not interfaces to plug-in cards; now days they are often even within the integrated circuit itself, so would only be visible under a microscope, and are fabricated when the integrated circuit is. Perhaps this could be explained better in these articles? W Nowicki (talk) 16:38, 18 July 2013 (UTC)
thread_title:  Article name 

message: Some processors, such as the 68000, have provision for slow devices on the memory/IO bus and have a line (DTAK, for "data transfer acknowledge") which the peripheral will assert to signify it's had enough time to read/write the bus. So it's not strictly true that increasing bus speeds required increasing peripheral speeds, at least in the case of asynchronous bus designs.  The whole world isn't an IBM PC, you know...or even an S100, for that matter. --Wtshymanski 18:53, 9 November 2007 (UTC)
thread_title: Bus speeds for different devices

message: The photograph nearest the top of the page states that the image is of a PCI Express bus... however the PCI Express article states that the PCI Express standard does not use a traditional bus, it uses lanes instead.  -- 71.207.13.141 (talk) 05:16, 6 December 2007 (UTC)
replies: text: Yes, but that's just on the electrical level. All the pins from different lanes are still arranged in a single strip. Hence why the connectors differ in size: they have a different number of lanes each. -- intgr [talk] 17:33, 6 December 2007 (UTC)

text: PCI Express is not a bus, neither is RS-232  —Preceding unsigned comment added by 70.55.0.135 (talk) 21:25, 8 June 2008 (UTC)
thread_title: PCI Express Bus Photo

message: I think the whole organization of "bus" articles related to data buses needs to be re-vamped. The way I think about it, a computing bus as described in this article is just a specific case of a data bus. For that matter, there is a whole family of data buses not addressed: those used to connect special-purpose computers in aircraft, cars, and probably lots of other applications. For example, RS-422, RS-485, ARINC 429, MIL-STD-1553, and CAN, to name a few. By the way, the term bus in my experience is commonly used to describe point-to-point (two device) communication networks. I would like to see a citation for the "must connect more than two devices" assertion.  —Preceding unsigned comment added by 63.114.24.9 (talk) 05:13, 9 February 2008 (UTC)
thread_title:  Generalization 

message: Why does data bus redirect here? They are entirely separate things. You to combine a data, address and control bus (or multiplex them all) to make a bus that is described in this article. Rilak (talk) 11:12, 13 April 2008 (UTC)
replies: text: I agree with this, although I'm not sure if a control bus is necessary in every bus.  However there is a worse terminology problem here which is the circularity of the definition; if we say "A bus is composed of a data bus, an address bus and a control bus," it still leaves the question, "What is a bus?"  If allowable by quotation guidelines, I'd recommend quoting the definition here: http://searchstorage.techtarget.com/definition/bus  (I found that definition the most helpful in clearing this word up; I'm unaffiliated with that site.) 99.193.239.11 (talk) 23:27, 10 June 2016 (UTC)
thread_title:  Data bus redirect? 

message: The article's lead explicitly rules out point-to-point links as being a "bus". Yet that is what HyperTransport is, and it's listed as a bus further down in the article. Furthermore, I think this is mostly semantics. You can add a discussion about the strictness (or lack thereof) for the dictionary definition of "bus", or even "not a bus", but by and large the common usage is that "bus" refers to whatever connects the various components of a computer together and vice versa (nobody actually calls HT a "point to point link" except in formal papers). If anyone objects to this and cannot reconcile it with a separate paragraph about the meaning of "bus", please discuss further. Ham Pastrami (talk) 04:38, 21 February 2009 (UTC)
replies: text: IEEE Std. 100 says a bus in the context of a microcomputer system connects "a number of devices" - that is, more than two. I don't think it's useful or appropriate to describe a point to point link as a "bus" since a bus implies that multiple devices can connect to it. I'm all in favor of common useage defining usage but not at the cost of ambiguity. Otherwise the word "bus" is meaningless.  --Wtshymanski (talk) 15:36, 21 February 2009 (UTC)
replies: text: A "number" is not "more than two", unless you are referring to another normative definition. The dictionary provides: (1b) an indefinite usually large total and (3) a distinction of word form to denote reference to one or more than one. The 1b definition rules out point-to-point links and traditional buses equally; neither kind of bus is typically built for a "usually large" number of devices. In practice, there are also several high-profile precedents: front side bus and back side bus connect only 2 devices, unless you also want to count the clock; the "AGP bus" would also be a misnomer. Again, the article as-is mentions HyperTransport in several places anyhow (really, as it should) and using a conflicting, interpreted definition (correct me if I'm wrong, but IEEE does not actually say "Point-to-point is not a bus") is what leads to ambiguity. You have the lead and the body claiming different things. Also, I'm not at all sure what is meant by the word "bus" becoming meaningless. Aside from that one sentence, the article provides a solid background on what a computing bus is. It's not like this creates the ability for someone to add "a computer bus is a monkey". Please keep in mind that Wikipedia is not a technical manual (see point 5 especially), and things like IEEE or dictionary definitions are not necessarily appropriate to define the scope of an article. Ham Pastrami (talk) 07:48, 27 February 2009 (UTC)
replies: text:  Why does the IEEE definition not then say "two or more" instead of "a number"? That would be clear and would have shown an intent by the IEEE to include point-to-point links. Dictionaries often don't define things by exclusion because dictionaries (unlike Wikipedia) have to worry about space.  A point-to-point link and a bus have significantly different properties - bus contention doesn't exist in a point to point link, for example. ( Recall all those desparate stunts in the 5 1/4 disk days for "networking" a classroom using nothing but the RS 232 ports and a bunch of diodes, pull up resistors, clever software, and optimism. RS 232 is not a bus and will bite the hand of anyone who treats it like one.)  What is the difference between a point to point link and a bus?  If they are synonymous, why are their two different terms? Personal computer users have long taken the Humpty Dumpty attitude towards words and definitions, starting with the murky idea of "formatting" a hard drive. I'm of the opinion that our technical vocabulary is the poorer for this practice. --Wtshymanski (talk) 14:59, 27 February 2009 (UTC)
replies: text: Perhaps the IEEE definition is intentionally vague for the express purpose of not locking down the concept to specific electrical implementations? Again, if you want to make a more specific distinction between the general idea of a bus and the difference between traditional and point-to-point, you can, you just need to be more clear that there is a wider context and not narrow the article's purported scope. Within its common English usage, the difference between a point-to-point link and a "bus" is the same between an apple and a fruit. One is a specific type of the other. Ham Pastrami (talk) 16:41, 27 February 2009 (UTC)
thread_title:  Contradiction and apparent attempt to exclude HyperTransport 

message: "Almost always, there was one bus for memory, and another for peripherals"
This is a contradiction with text later in the article and also false. While a separate I/O space existed on Intel processors, this is only true for them and derived CPUs such as the Zilog Z80. On the other hand, Motorola processors, MOS CPUs etc. mapped hardware registers in the same memory space with RAM and ROM. They were accessed using the same instructions and only one data bus existed on the majority of 1980s computers. --213.130.252.119 (talk) 11:17, 18 April 2010 (UTC)
replies: text: (replying two years late...) No, this is not false. The statement is discussing much older systems, the mainframes and minicomputers of the 1950s and 1960s. These generally had completely separate memory and I/O buses. Digital's PDP-11 of 1969 was one of the first systems to unify memory and I/O into a single bus. --Colin Douglas Howell (talk) 00:48, 21 August 2012 (UTC)
thread_title:  BS detected 

message: Hi guys,
I think it would make sense to merge the Address bus article into a section within this article. It's a very small, barely maintained article, and its content seems very similar to that of this article. Or is there some big distinction between the two concepts I'm overlooking?
InternetMeme (talk) 21:58, 12 January 2018 (UTC)
replies: text: There's no "data bus" article, for example, so just mentioning that some particular CPUs have separate address and data buses, possibly of different sizes and discussing that in this article makes sense to me. Guy Harris (talk) 23:38, 12 January 2018 (UTC)

text: Support merger; Address bus is a disaster of an article, probably because there isn't enough content for a stand-alone article. power~enwiki (π, ν) 19:38, 12 February 2018 (UTC)

text: Support - better not to waste the reader's time with a jump to an article that provides little additional content, which could be non-redundantly incorporated here. --Wtshymanski (talk) 02:01, 13 February 2018 (UTC)
replies: text:  Klbrain (talk) 05:17, 14 April 2019 (UTC)
thread_title:  Merger discussion 

message: :The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion. 
The result of the move request was: No consensus to move. There is dispute whether "computer bus" is a common enough name for the article content that it works as an article title. (non-admin closure)  (t · c) buidhe 01:12, 29 January 2022 (UTC)
replies: text: Bus (computing) →  – Per WP:NATURALDISAMBIG and WP:CONCISE. Rublov (talk) 17:19, 14 January 2022 (UTC)
replies: text: I think using "Car axle" as a naturally disambiguated title would be perfectly acceptable too. And a quick Google search for "computer bus" yields over a quarter of a million search results. Seems common enough to me. Rreagan007 (talk) 01:06, 17 January 2022 (UTC)
replies: text: Well, I get 323k hits for "computer bus", which seems like it should be enough, except "data bus" produces 3.6 million hits, which demonstrates how relatively uncommon "computer bus" is in relevant context. --В²C ☎ 01:24, 17 January 2022 (UTC)
replies: text: Are you proposing that the article be moved to Data bus? Rreagan007 (talk) 02:05, 17 January 2022 (UTC)
replies: text: No, I think the current disambiguated title meets criteria the best, certainly better than the proposed title. My point about data bus is that it’s a type of “computer bus”, and yet it’s far more commonly used in the relevant context. Again, it shows that “computer bus” is a relatively uncommon term. —В²C ☎ 21:24, 17 January 2022 (UTC)
replies: text: WP:NATURALDISAMBIG covers (in fact, was written to cover) this exact case, though:  (emphasis mine) As you yourself observe, the term is used hundreds of thousands of times on the web. It's even used in the article where ambiguity isn't an issue, because it's a natural way to refer to the article's topic. Rublov (talk) 22:01, 17 January 2022 (UTC)
replies: text: I’m well aware of that wording and my interpretation is that it discourages natural disambiguation in a case where the natural disambiguation candidate is not merely “not as commonly” used as the preferred-but-ambiguous title (in this case, “bus”), but it’s less commonly used by more than an order of magnitude. I don’t think you can ascertain whether the WP:NATURALDISAMBIG “also commonly called” hurdle is met by a raw count of number of ghits.  To be “commonly called” something it has to be relative to how often it’s referenced. The ghit count for “data bus” gives ″us an idea of the order of that.  And it overwhelms the hit count for “computer bus”.  A term that is used an order of magnitude less often is not used sufficiently often to say the subject is “commonly called” that.  —В²C ☎ 00:32, 18 January 2022 (UTC)

text: The standard for WP:RECOGNIZABILITY in our article titles is "The title is a name or description of the subject that someone familiar with, although not necessarily an expert in, the subject area will recognize." I highly doubt that someone familiar with the subject matter of this article would be confused by the proposed title as you have suggested. Rreagan007 (talk) 01:27, 22 January 2022 (UTC)
replies: text: I’m a computer engineer and am opposed precisely because I don’t recall ever encountering the term proposed for title here. For a sanity check I verified with ngrams. Again, compared to other bus terms commonly used in the context of computing, “computer bus” is relatively obscure.  —В²C ☎ 06:15, 24 January 2022 (UTC)
thread_title:  Requested move 14 January 2022 

message: In this edit, User:Chagropango added a reference for the claim in the first paragraph in .
I downloaded the paper from its ResearchGate page.  It appears to "support" that claim by having copied a huge amount of text from this article; the date of the paper is January 2016 (it's from the Consumer Electronics Show, which is held in January), and a version of this article from 2016-10-30 appears to contain most of the text that appears in the paper (starting with the first paragraphs of both), so I'm guessing the author of the paper copied from this article, rather than somebody copying from the paper into this article.
The good news is that it means this article isn't a huge copyright violation; the bad news is that it means that paper can't be used as a reference for anything in the article. Guy Harris (talk) 20:04, 27 June 2022 (UTC)
replies: text: The reference should be removed, because using it would be a case of citogenesis, but I already did that.  Nothing else needs to be done - this article isn't copying from the paper, the paper is copying from the article. Guy Harris (talk) 07:56, 29 June 2022 (UTC)
thread_title:  The "Computer Busses, Ports and Peripheral Devices" reference appears to have copied from this page 

message: I don't agree with #Implementation details statement that "An attribute generally used to characterize a bus is that power is provided by the bus for the connected hardware." For contrary examples, Power over Ethernet devices get their power from the central hub, but are not considered a "bus". And as the article mentions, USB devices are often but not always powered by the USB bus's power supply pin but are considered a "bus", and avionics buses don't.
Sometimes "buses" are distingushed in that that a "bus" is for localized communication, while a "network" is for more widespead communication.  But then there are things like "Controller-area network bus" which is called both a "network" and a "bus", it is localized to within a vehicle. And there are Network on a chip which are localized but is a network but not called a "bus".
Maybe that paragraph can be dramatically shortened to just be that a "bus" resembles a busbar. Em3rgent0rdr (talk) 18:27, 21 July 2023 (UTC)
replies: text: That whole section is largely unsourced. Perhaps editors are just making stuff up. The busbar connection is also not properly supported by a source. ~Kvng (talk) 03:51, 25 July 2023 (UTC)
thread_title:  Claimed distinction that buses provide power is not necessarily true 

message: The article says, in , that
What CPUs have those pins, and what are they?  The list of examples includes UARTs and "Ethernet", but does this mean that the pins in question would be pins from an on-CPU-chip UART to go to a serial port and pins from an on-CPU-chip Ethernet adapter to go to a PHY or to an Ethernet network, or does it mean that they would be pins that connect either to a support chip, such as a northbridge, that's an I/O bus (ISA, EISA, PCI, PCIe, etc.) interface, or that directly connect to the I/O bus?
If it's the former, then the examples are examples of the types of pins.  However, if it's the latter, the UART and Ethernet examples are examples of peripherals that attach to the I/O bus to which the CPU pins connect.
(And the answer might depend on which type of CPU/SoC chip is being discussed.) Guy Harris (talk) 00:41, 30 July 2023 (UTC)
replies: text: There are no citations in this section. I would thin this material to remove unnecessary detail and ambiguity. ~Kvng (talk) 02:34, 30 July 2023 (UTC)
thread_title:  CPUs with a second set of pins