Talk:Serial port

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Moving stuff here, needs work. I get the impression that the FOLDOC material mentions the PC as a special case, and at any rate USB / Firewire are the current standards.

Usually, the expression "serial port" refers to the old PC "serial port" used for mice. (what's the proper name for this?)

connected to peripherals which communicate using a serial (bit-stream) protocol. The most common type of serial port is a 25-pin D-type connector carrying EIA-232 signals. Smaller connectors (e.g. 9-pin D-type) carrying a subset of EIA-232 are often used on personal computers. The serial port is usually connected to an integrated circuit called a UART which handles the conversion between serial and parallel data.

The serial port can be used to connect terminals (VDUs or teletypewriters, TTYs), printers, modems and other serial peripherals. Two computers can also be connected together directly via their serial ports.

combine with serial communications

Please see the discussion at serial communications on whether these two pages should be combined. Fpahl 14:56, 14 Sep 2004 (UTC)

Line disciplines

Can anyone tell me what is meant by line discipline? Maybe this can be reworked into the article? —The preceding unsigned comment was added by Bvankuik (talk • contribs) 04:42, 23 February 2006 (UTC).[reply]

A "line discipline" is a concept on many Unix-like systems. On a serial port, or something such as a pseudo terminal or the system console of a personal computer or workstation, there's a low-level driver that controls the hardware (for a serial port) or the other entity (for a pseudo-terminal or console), which supplies a sequence of bytes received from the port or device and accpets a sequence of bytes to be sent to the port or device; it doesn't do any formatting, line-editing (erase, kill, etc. characters), and so on. A "line discipline" module can be installed on that device; it's another piece of operating system kernel code that implements formatting (converting line feed to carriage return/line feed on output, expanding tabs, etc.), and input processing (converting carriage return to line feed on input, line-editing, etc.) for the standard "tty" line discipline, and that can implement other things if the serial port isn't being used for a terminal. For example, on older Sun workstations, the keyboard and mouse were attached to serial ports, and a special line discipline was used to implement the protocols the keyboard and mouse used, and SLIP and the Point-to-Point Protocol (PPP) are often implemented as line disciplines if they're being run on a serial port.

Some systems, such as derivatives of UNIX System V, use pushable STREAMS modules rather than line disciplines for this purpose.

This information doesn't belong in this article, as it's a software concept specific to a particular family of operating systems. Guy Harris 00:38, 12 October 2006 (UTC)[reply]

Could we please have some more pictures?

I'm just a reader and I'm finding it a bit difficult to tell the difference between a parallel and series port, and I thought Wikipedia would be better off with some better/more pics (there isn't any picture of a parallel port, to distinguish the two).

I think maybe diagrams would be more useful than pictures - you can't tell by looking at a connector on the back of a box if the connector is used for a serial port or a parallel port - and the ever-loving IBM PC confounded the issue by using the same family of connectors for serial, parallel, video, joystick and network connectors - so appearances were less than useful. There's a bit-serial diagram at Asynchronous start-stop but we need a diagram showing both together, I suppose.. --Wtshymanski 03:20, 14 April 2006 (UTC)[reply]

For PC's it's almost guaranteed that a male D-25 or D-9 is a serial port, while a female DE-25 is a parallel port. The Joystick port on typical PC's was always D-15, and video the D-9 size but with 15 pins.--Bert490 05:49, 15 July 2006 (UTC)[reply]

Added a better image, I suggest the old one be removed, it's very hard to see what it is. --DuLithgow 14:10, 24 May 2006 (UTC)[reply]

You are right: can't see the pins on the old one. I removed it after transferring the DE-9 link.--Bert490 05:49, 15 July 2006 (UTC)[reply]

I added a picture of my PCI-E card but I have used that picture on 2 articles already. Towel401 22:11, 11 November 2007 (UTC)[reply]

Infobox cruft

I really really hate the infobox. Just what articles are encrufted by this...thing? What purpose does it serve? Why must we spend so much time cluttering up pages with things like this when 1,000,000 articles don't even have *references*? --Wtshymanski 17:52, 11 October 2006 (UTC)[reply]

Look at the inaccuracy of this specimen. Invented 1969? Don't think so, computers had serial ports before Revision C of RS-232. Superseeded? Maybe "Superceded" ? Or are we talking about wheat? Anyway, a USB port is incompatible with RS 232 and so the two are not interchangeable. Width 5-9 bits? In a serial port? That's a character frame, anyway - and often 10 bits, or more, depending on how you count the start/stop bits. Speed 115 kbits? That's not RS-232 - some IBM PC serial ports do this, but it's hardly standard. "Style Serial" conveys *nothing* to the reader. Hotplugging is a PC-centric concept and unexplained in the article. What does "external" mean in this context? Horrible, horrible...away with it. --Wtshymanski 17:58, 11 October 2006 (UTC)[reply]

Picture with a numbered pins

Suggestion, one can add more information on this article by replacing the current pictures with one that have numbered pins —The preceding unsigned comment was added by Wk muriithi (talk • contribs) 10:55, 27 January 2007 (UTC).[reply]

Address and IRQ

Eh? This information used to be here. Where's the link that says where it went? Jim.henderson 22:56, 3 February 2007 (UTC)[reply]

A list of port addresses and IRQs for ONE possible computer type does not belong here. And, as anyone who ever tried to get two serial cards to share an IRQ (in an IBM-compatible machine with the so-called "ISA" IO bus), serial ports can't share the same IRQ if you actually expect to use both at the same time. Where are the port addresses for, oh, say, a Kaypro 10 or a Power Mac? And are these even meaningful in the context of PCMCIA adapters and "virtual" ports? --Wtshymanski 15:36, 11 February 2007 (UTC)[reply]

Thank you; the former is an excellent question. Kindly include this information in the section, or links to Wikipedia pages or external sites that answer the question. So far, we have found a small table with information useful for dealing with the majority of serial ports, but yes, this is a matter in which more would be better. If it gets to be a lot of data, then the section should be broken out into its own article with a link, but thus far it is small. As for the latter question, alas, I do not understand the relevance, but assuming it is relevant it should also be included in this article or a linked one. Jim.henderson 02:01, 12 February 2007 (UTC)[reply]

"Byte" versus "Word"

It is my humble view that it would be more appropriate to refer to the smallest unit of data as "word" rather than "byte", as bytes intuitively indicates the smallest data unit in computers, which can be individually addressed and which typically has a fixed size for a specific computer setup, whereas "word" sets it aside for data communication devices, where the smallest data unit may assume different sizes for different communiaction sessions. Alan Turing 13:02, 7 March 2007 (UTC).

Trying to clean this up

There is a lot of technical stuff here that sort of belongs to the RS-232 article, this article seems to have covered the role in modern personal computers fairly well, so I am tempted to move all the technical stuff over to RS-232 but keeping the 'settings' section might be useful for people trying to configure their serial port. Also there is a lot of duplicated information between the Serial port, serial cable and RS-232 article that could be gotten rid of Towel401 (talk) 22:28, 23 November 2007 (UTC)[reply]

Agree. The stuff that is actually discussed in the standard should be in the RS 232 article. Not all serial ports are RS 232! How start/stop communications works in general, and history, should be in asynchronous communication. The serial cable article ought not to exist since it overlaps RS 232, serial port, and asynchronous communications - part it out over all three and save anything that belongs. Port addresses and IRQs belong in the IBM PC article, if talking about the specific example of an IBM PC serial port. This article should be careful to distinguish between "serial ports" in general and details which are specific to one particular type, such as the IBM PC and its descendants. --Wtshymanski (talk) 22:45, 23 November 2007 (UTC)[reply]

Networking configuration

 I tought it should be mentioned that this port is used for initial configuration of networking devices such as routers or switches. I don't know about all the manufacturers of this sort of product, but Cisco uses this method.