Editing Serial interface

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A '''serial interface''' is a computer interface that delivers data down a single wire or single pair of wires.
Serial interfaces are a concept, for which there are numerous implementations, and numerous connectors.

The most widespread is the '''RS-232''' standard, using DB-25 and later DE-9 connectors<ref group="footnote">DE-9 is very often mislabelled as "DB9". 'E' and 'B' stand for the ''size'' of the [https://en.wikipedia.org/wiki/D-subminiature D-subminiature port]. DE-9 is smaller than DB-25, whereas an actual DB-9 port (if one existed) would be the same size as a DB-25 but have fewer pins</ref>, both male on the host/device and female on the cable (both ends).

Older Macintosh computers had often two female mini-DIN-8 sockets, using RS-422 signals to Apple-specific peripherals such as printers, and RS-232 signals (with adapter) to third-party peripherals such as modems.

RS-232 and RS-422 serial interfaces are now mostly superseded by [[USB]]; laptops in particular typically omit the serial port now.

==IBM PC==
On PCs the serial port is also called the '''COM''' port.

Desktop PCs may still have a 9-pin RS-232 port present, if not on the back I/O panel more often as a IDC-10 socket on the motherboard for connecting to an optional I/O bracket with the DE-9 port. Note that there exist two types of wiring to IDC-10 socket: AT/Everex ("Straight Through": same numbered pin) and DTK/Intel ("Cross over")<ref name="bodenzord">Bodenzord—[http://www.bodenzord.com/archives/117 RS-232 PC Serial Port Pinout Conventions]. Dated 2013-10-03. Retrieved 2018-12-04</ref>.

==PC mouse==
Among its many uses, the PC's "COM" port was used for [[mouse|mice]], especially before the [[PS/2 interface]] was widely adopted.
[[Mouse Systems]] and [[Microsoft]] had different protocols over RS-232 and other mouse manufacturers supported either (or both with a switch on the mouse). Microsoft's protocol was extended for a third mouse-button and later for a [[scroll wheel]].<ref name="e2">Everything2.com—Mouse protocol. [https://everything2.com/title/Mouse+protocol Archived from http://www.hut.fi/~then/mytexts/mouse.html]. Dated 2003-01-12. Retrieved 2018-12-04</ref>

Be aware that some [[Bus mouse|bus mice]] did also use DE-9 connectors but are incompatible with serial mice.

==Gallery==
===Connectors===
<gallery widths=250 heights=187>
File:Serial interface -- DE-9 socket.jpg       | DE-9 male socket on a Dell desktop PC
File:Serial interface -- DE-9 plug.jpg         | DE-9 female plug from a Key Tronic serial mouse
File:Serial interface -- Macintosh sockets.jpg | Mini-DIN-8 female sockets on a Macintosh Classic
</gallery>

===Examples===
<gallery widths=250 heights=187>
File:Datalux POGUC -- top.jpg                  | [[Datalux SpaceSaver]] POGUC, with the curious combination of PS/2 for keyboard, and serial for the [[trackpad]]
</gallery>

==Footnotes==
<references group="footnote"/>

==References==
<references/>

[[Category:General-purpose protocols and interfaces]]
[[Category:Pointing device protocols and interfaces]]