Editing Model M keyboard (section)

== Design ==
{{More citations needed section|date=April 2012}}

The variant most commonly referred to as "Model M" is Part No. 1391401,<ref>{{Cite web |title=IBM Enhanced Keyboard - Deskthority wiki |url=https://deskthority.net/wiki/IBM_Enhanced_Keyboard#1391401 |access-date=2022-11-12 |website=deskthority.net}}</ref> on which many other variants were based. This model, known as the Enhanced Keyboard, included IBM's patented [[buckling spring]] design<ref>{{US patent reference | number = 4528431 | y = 1985 | m = 07 | d = 09 | inventor = Edwin T. Coleman III | title = Rocking switch actuator for a low force membrane contact sheet}}</ref> and swappable keycaps.

The Model M's design has been widely described as reliable, and the design has not changed significantly over time.<ref>{{Cite web |last=Wain |first=Sarah |date=2019-12-30 |title=How Technology Has Changed In The Last 20 Years |url=https://www.mymemory.co.uk/blog/how-technology-has-changed-in-the-last-20-years/ |access-date=2022-11-12 |website=MyMemory Blog |language=en-GB}}</ref> Thanks to the M's design, including its heavy [[steel]] backplate and strong [[plastic]] frame, many early Model M Keyboards are still functional four decades past release.

The Model M's buckling spring key design specification<ref>{{Cite web |last=SharktasticA |title=IBM buckling spring {{!}} Shark's Wiki |url=https://sharktastica.co.uk/wiki?id=ibmbucklingspring |access-date=2024-01-03 |website=Admiral Shark's Keyboards |language=English}}</ref> gives it a unique feel and sound. Unlike more common and lower-end rubber dome designs, buckling springs give users a notable tactile and auditory feedback. Because of its more defined touch, some users report they can type faster and more accurately on the Model M than on other keyboards.<ref>{{cite web | url= http://weblogs.asp.net/dreilly/archive/2005/05/04/405591.aspx | title = My Clickety IBM Keyboard – RIP|last=Reilly|first=Doug | work=Doug Reilly's Weblog| publisher = Microsoft | date = May 4, 2005 |access-date=2011-01-24| archive-url=https://web.archive.org/web/20060217231454/http://weblogs.asp.net/dreilly/archive/2005/05/04/405591.aspx|archive-date=2006-02-17}}</ref><ref>{{cite web | url = http://www.ryancramer.com/journal/entries/model-m-keyboard/ | title = IBM Model-M Keyboard | publisher = Ryan Cramer Design | last = Cramer | first = Ryan | date = 2008-05-05 | access-date = 2008-05-13 | archive-date = 2020-10-23 | archive-url = https://web.archive.org/web/20201023055019/http://www.ryancramer.com/journal/entries/model-m-keyboard/ | url-status = dead }}</ref> Additionally, many model M enthusiasts believe that tactile-feedback keyboards like the Model M reduce stress on the hands, preventing or even reversing [[repetitive strain injury]].<ref>{{cite web|url=http://catb.org/esr/faqs/tactile-keyboard-faq.html|title=Tactile Keyboard FAQ|access-date=2021-04-21}}</ref> Significant pressure is required to press the keys, and a pronounced sound results to help typists previously trained on typewriters who had become accustomed to that level of feedback.<ref name=":0" /> This resulted in the Model M sometimes being referred to as the "clicky keyboard."<ref name=":0" />

Until the late fourth-generation variants, most Model Ms were manufactured with a 1.25" slotted, circular speaker grille in their bottom surfaces. Relatively few contain an actual speaker, however, which was useful only for sounding beep codes on older terminal systems. The most common P/Ns with speakers are 1394540 and 51G872, made for RS/6000 UNIX workstations.

Model Ms have been manufactured to quite a number of different interface and connector standards, some of which (such as the 5-pin DIN used on 5250 terminals) are poorly documented and have had to be reverse-engineered by enthusiasts. Early variants shipped with the [[PC XT]] and [[PC AT|AT]] used connectors specific to those systems.  After the introduction of the PS/2 most shipped with a connector for a [[PS/2 port]]; these included the 1391401. Unicomp introduced support for [[Universal Serial Bus|USB]].

Older model Ms used a detachable cable utilizing [[Shielded data link connector|SDL]]. Later Lexmark and Unicomp variants used a fixed cable.

[[File:Model M Logo Comparison.jpg|thumb|The square aluminium badge on a 1390131 series keyboard compared to other variants]]