Talk:Parallel port

message: External links were filling up with commercial and advertising sites and were removed.  Please add new links that conform to WP guidelines and refrain from adding commercial links WP:EL. - Thanks Calltech 16:52, 18 December 2006 (UTC)
thread_title:  External links section removed 

message: All our information about the parallel port is split into various disconnected sections in at least four different articles, none of which is very useful. They need to be merged into one comprehensive article. --88.110.235.235 22:18, 13 January 2007 (UTC)
replies: text: That doesn't require separate articles. None of the separate articles are substantial enough that they couldn't be made into sections of this article. --88.109.83.157 23:11, 15 January 2007 (UTC)

text: I don't agree with the above suggestions.  IEEE 1284/Parallel Port/LPT pretty much cover the same thing, with different names.  I'd just ensure each name permutation is covered in the merged article, which I'd expect would be done automatically. - MSTCrow 05:57, 6 March 2007 (UTC)

text: Centronics should retain its own article focusing on the company; the information on the parallel port should probably be merged in though. Fourohfour 18:37, 18 March 2007 (UTC)

text: The Centronics article should retain all of the history on how the interface was developed and how it became the defacto standard for printers. This interface was a significant and historical development in the computer industry. The details of how the Centronics interface was developed; such as why a 36 pin Amphenol connector was selected, belong in the Centronics article not in the Parallel Port article. -- SWTPC6800 16:28, 30 April 2007 (UTC)
thread_title:  Merger? 

message: This article seems to be about the IBMoid PC implementation of the Centronics-style parallel port, rather than the port itself.
While this information can be useful, and may very well bear inclusion (along with other implementations), the article should discuss the particulars of the interface itself—including signaling, and the 36-pin micro ribbon connector that was originally used at both ends of the cable, before IBM began substituting the DB-25 at the host end.
:And the DEC DB-37 connector, TI 46-pin card-edge connector and Data General 50-pin AMP connector.  Tandy used a header connector, but I don't have a reference on that.  --— Gadget850 (Ed) talk -  19:42, 31 October 2007 (UTC)
thread_title:  Lots about IBMoid-PCs; not enough about the interface, itself 

message: If there is an unused LPTx slot, the port addresses of the others are moved up. (For example, if a port at 0x3bc does not exist, the port at 0x378 will then become LPT1.) The IRQ lines, however, remain fixed (therefore, 0x378 at LPT1 would use IRQ 7). The port addresses assigned to each LPTx slot can be determined by reading the BIOS Data Area (BDA) at 0000:0408.
Should this in fact read as follows? I'm not sure enough to make the edit.
If there is an unused LPTx slot, the port addresses of the others are moved up. (For example, if a port at 0x378 does not exist, the port at 0x278 will then become LPT1.) The IRQ lines, however, remain fixed (therefore, 0x278 at LPT1 would use IRQ 6). The port addresses assigned to each LPTx slot can be determined by reading the BIOS Data Area (BDA) at 0000:0408.
The current sentence implies that there will be no change, as 0x378 is LPT1 as standard.
:Be bold. This needs fixing and a citation added to nail down the right addresses, ports and interrupts.Cuddlyable3 (talk) 05:57, 23 May 2008 (UTC)
thread_title:  Port addresses 

message: A diagram like this would be nice. — Omegatron 22:19, 14 January 2008 (UTC)
replies: text: There is actually an infobox for this:   --— Gadget850 (Ed) talk -  02:47, 14 March 2008 (UTC)
thread_title:  Diagram 

message: I agree this would be nice to have. AFAIK there is no specification since the port can deliver much faster than a printer, the originally intended peripheral, requires. However the speed is relevant for other uses of the port such as
* input sensing e.g. some data logging uses
* data exchange between PCs
It may be difficult to find verfiable sources about speed rather than just OR. Cuddlyable3 (talk) 13:32, 24 May 2008 (UTC)
thread_title:  needs info on speed

message: how exactly did the PC variant differ from the original? Plugwash (talk) 03:20, 29 December 2008 (UTC)
thread_title:  PC variant 

message: What is this pins used for? Are they "reserved"? --MrBurns (talk) 08:51, 6 April 2009 (UTC)
thread_title:  Centronics pins 15, 18, 34 and 35 are missing 

message: Maybe it is important to note, that modern PC extension cards, like PCI Express parport cards use a logic high level of 3.3V.
I've seen pages linking to this Wikipedia-Topic: "but they say its 5V". Just to avoid problems, which I've stumbled.  — Preceding unsigned comment added by Jedzia (talk • contribs) 11:43, 30 March 2014 (UTC)
thread_title:  Logic Levels 

message: The article contains the following information ( by Uwezi ):
:Pin 25 on the DB25 connector might not be connected to Ground on modern computers.
Well, this IMHO just does not make any sense why something like this should become the norm. I can, however, see one reason for this to occur, but that is by a design error only and should be regarded as a bug. If someone knows of any legitimate reason for the pin 25 to be left unconnected or knows a particular example of common hardware with this property, please feel free to add a citation and/or further clarification. I have just verified the parallel port wiring on a couple of motherboards and on 1 LPT card (some of which could hopefully be considered modern by the 2011) and found none having the pin 25 not connected to ground. Meanwhile, I'm thus marking this information with .
As for the above hinted possible reason for the pin 25 to remain unconnected, I have recently discovered a possibility for this to occur with Gigabyte motherboards. Gigabyte motherboards seem to be using a slightly modified pin-out for the LPT header (pin 24 swapped with key/pin 26) which, if used with a generic-wired (and unkeyed) bracket cable, would leave the pin 25 unconnected. Unfortunately, it seems even Gigabyte themselves are selling brackets with the  generic wiring only that are not compatible with their own modified pin-out. I have recently discovered this myself (Czech Republic, as of 2015 – unsuitable bracket bought from one e-shop and the very same being confirmed by another e-shop to be the only available; in both cases the bracket was described along with Gigabyte's part numbers), but this has already been reported as early as in 2009 on Tom's Hardware. However, as noted above, this is a design error in the bracket cable and the pin 25 would be correctly connected to ground with the appropriately wired cable, so this might not have been the reason for putting this information in the article.
And if this was the original reason for putting the information there, the statement should be at least rephrased to reflect the fact this is by a wiring error only. (Which I might do myself some time in the future, if no objections arise...)
--JITR (talk) 15:58, 7 October 2015 (UTC)
replies: text: @JITR I am inclined to agree that this is a fault / wiring error and not the norm.
My big issue though is why a 25-pin connector had so many pins connected to Ground when these pins could have been put to better use, for example, as additional data lines making the parallel interface capable of 16-bit transfer when it began being used for more than just a printer interface. 81.108.186.222 (talk) 12:55, 6 March 2022 (UTC)
thread_title:  Pin 25 not connected? 

message: There is a significant gap in the history section between the earliest use of this connector, which per the text here (it's news to me) required the host computer to convert character data into dot matrix bit patterns, and the slightly later usage wherein the 7 data bits in the connector were used to send ASCII characters and the character generation was done in the printer. Certainly the first printers I dealt with that used this interface (on CP/M machines) just took ASCII data. More sophisticated dot-matrix printers did have a "binary" mode that could be used for graphics. Jeh (talk) 14:24, 9 October 2016 (UTC)
replies: text: Looks like  has changed the text to the effect that the original Centronics-interface printers did take ASCII data. Thanks. Jeh (talk) 18:53, 9 October 2016 (UTC)
replies: text: Lots more to come... Maury Markowitz (talk) 20:26, 9 October 2016 (UTC)
replies: text: Thnaks veru mach Dian Nikolow (talk) 11:06, 6 March 2024 (UTC)
thread_title:  Missing history info - transition from really dumb printer to ASCII input? 

message: It might be worth mentioning that the DataProducts interface was more different than just a different connector. The handshaking was different. I built a couple of interfaces to these back in the 70s. I can probably dig out details on the differences. Jeh (talk) 21:13, 9 October 2016 (UTC)
thread_title:  DataProducts interface 

message: The table "Bit-to-pin mapping for the Standard Parallel Port (SPP)" uses the tilde (~) to specify inverted signals.
In the good old days of computers, the slash forward was usually used in writing, when the line above was not feasible, e.g. /Strobe, /Busy.
The table designates pins, not signals, but it might nevertheless be more common to use the slash instead of the tilde.
--Stefanhanoi (talk) 18:12, 30 September 2021 (UTC)
thread_title:  Writing Convention for Inverted Signals 

message: What was the idea behind the original IBM hardware assigning an IRQ to the parallel port?
Does a parallel port/printer combination actually generate interrupts, and if so, under what conditions?  There's only a few lines like ACK and PAPER OUT that go back into the port in the computer and surely these don't generate an interrupt?  Valgrus Thunderaxe (talk) 17:09, 27 June 2022 (UTC)
thread_title:  Parallel port IRQ 

message: Is this manufacturer important enough to be included in this page? Their Wikipedia page has no parallel ports mentioned anywhere. 2A01:112F:90C:BD00:5E44:E0F9:CA35:8335 (talk) 14:53, 21 March 2024 (UTC)
replies: text:  The manufacturer is important, but the sentence makes no sense. I'll remove it. ;) --Eliza Winterborn (talk) 16:28, 12 May 2024 (UTC)
thread_title:  Biostar