Editing Model M keyboard (section)

== History ==
[[File:Capuchon.jpg|thumb|Keycap in a French Model M]]

The Model M keyboard was designed to be less expensive to produce than the [[Model F keyboard]] it replaced. Principal design work was done at IBM in 1983{{En dash}}1984, drawing on a wide range of user feedback, ergonomic studies, and examination of competing products. Its key layout, significantly different from the Model F's, owed much (including notably the inverted-T arrangement of its arrow keys) to the LK-201 keyboard shipped with the [[VT220]] serial terminal.<ref>{{cite web |last=Edwards |first=Ben J |date=2020-04-15 |title=Why I Still Use a 34-Year-Old IBM Model M Keyboard |url=https://www.howtogeek.com/661430/why-i-still-use-a-34-year-old-ibm-model-m-keyboard/ |access-date=2021-04-19}}</ref>

Production of Model M keyboards began in 1985. They were often bundled with new IBM computers. While today primarily associated with the IBM PC and its successors, it actually first shipped with the [[IBM 3101|3161 terminal]]<ref>{{cite web|url=https://deskthority.net/wiki/IBM_Enhanced_Keyboard|title=IBM Enhanced Keyboard (Deskthority)|access-date=2021-05-16}}</ref> and was deployed across several other IBM product lines as well, notably including the [[IBM 5250|5250 terminal]] and the [[IBM RS/6000|RS/6000]].

They were produced at IBM plants in [[Lexington, Kentucky]]; [[Greenock|Greenock, Scotland]]; and [[Guadalajara|Guadalajara, Mexico]]. The most common variant is the IBM Enhanced Keyboard identified by IBM assembly part number 1391401, the U.S. English layout keyboard bundled with the [[IBM Personal System/2]]. Until around 1993, most Model Ms included a coiled, detachable cable, with either an [[IBM Personal Computer/AT|AT]] (pre-1987) or [[PS/2 connector]], in 5- and 10-foot lengths (1.5 and 3 meters). From about 1994 onwards, flat non-detachable cables were used to reduce manufacturing costs; however, IBM retained its 101-key layout, never implementing the [[Microsoft Windows]] keys common on other keyboards from that time. Unicomp later designed a 104-key Model M with Windows keys.

On March 27, 1991, IBM divested a number of its hardware manufacturing operations, including keyboard production, forming [[Lexmark|Lexmark International]].<ref>{{cite news|url=http://newsroom.lexmark.com/newsreleases?item=30894|title=Lexmark celebrates history of excellence, innovation at 20-year anniversary|work=PR Newswire|date=March 27, 2011|access-date=2019-08-31}}</ref><ref>{{cite web|url=http://rulings.cbp.gov/detail.asp?ru=544887&ac=pr|title=Customs Ruling HQ 544887|publisher=U.S. Customs and Border Protection|date=October 2, 1992|access-date=October 12, 2014|archive-url=https://web.archive.org/web/20160321192516/http://rulings.cbp.gov/detail.asp?ru=544887&ac=pr|archive-date=March 21, 2016|url-status=dead}}</ref><ref>{{cite web|url=http://ibm.com/ibm/history/history/year_1991.html|title=IBM Archives: 1990s|date=23 January 2003|publisher=IBM|access-date=2008-09-16}}</ref><ref>{{cite news|url=http://query.nytimes.com/gst/fullpage.html?res=9D0CE2D9173CF931A15751C1A967958260|title=The Executive Computer; Can IBM Learn From a Unit It Freed?|work=The New York Times|first=Peter H.|last=Lewis|date=December 22, 1991|access-date=2008-09-16}}</ref> Lexmark continued manufacturing Model M keyboards in the United States, United Kingdom, and Mexico, with IBM as their major customer.<ref>{{cite news|url=http://findarticles.com/p/articles/mi_m0EKF/is_n1891_v37/ai_11677212|title=Keyboard vendors punched on prices|work=Electronic News|first=Bernard|last=Levine|date=1991-12-16|access-date=2008-09-16|archive-url=https://web.archive.org/web/20111112165632/http://findarticles.com/p/articles/mi_m0EKF/is_n1891_v37/ai_11677212/|archive-date=2011-11-12}}</ref> Many of these keyboards are identified by IBM assembly part numbers 52G9658, 52G9700, 71G4644, 82G2383, and 42H1292, which were bundled with [[IBM PS/ValuePoint]] and [[IBM PC Series]].

Over the next four years, cost pressure led to several minor design changes intended to lower the part and fabrication costs of Lexmark Model Ms.<ref>{{cite news|url=http://findarticles.com/p/articles/mi_m0EIN/is_1994_Dec_12/ai_15970392|title=Lexmark International Reports Best Year Ever Since Independent of IBM|work= Business Wire|date=December 12, 1994|access-date=2008-09-16|archive-url=https://web.archive.org/web/20081204111137/http://findarticles.com/p/articles/mi_m0EIN/is_1994_Dec_12/ai_15970392|archive-date=2008-12-04}}</ref> The case and metal backplate were repeatedly lightened. The cable jack and detachable SDL cable were replaced with a fixed cable. Some variants were made with a single color for key legends.

In 1995 Lexmark made the most sweeping design change in the Model M's history, altering the size and location of the internal controller board. While the new "press-fit" design successfully lowered manufacturing costs by eliminating the two ribbon cables and separate LED daughterboard of older versions, the controller's new card-edge connector proved to be a failure point that shortened the keyboard's average lifetime. The classic era of the Model M is generally considered to have ended with this change, though a few on the older pattern continued to be made at Greenock and Guadalajara until 1999. Relatively few press-fit model Ms have survived.

During the Lexmark years, a few Model M variants were manufactured with rubber-dome key switches rather than buckling springs. Due to these switches' comparatively short durability, few of these variants have survived. Despite their rarity, today's enthusiasts and collectors do not value them nearly as highly as the more common buckling-spring variants.

A five-year agreement obligating IBM to purchase nearly all of its keyboards from Lexmark expired on March 27, 1996.<ref>{{cite web|url=http://getfilings.com/o0001001288-97-000006.html|title=Lexmark International Group 1996 annual report, SEC Form 10-K|publisher=Advameg|date=March 24, 1997|access-date=2014-10-12}}</ref> Lexmark exited the keyboard business, selling related assets to IBM and Maxi Switch.<ref>{{cite news|url=http://plasticsnews.com/article/19951204/NEWS/312049998/lexmark-exits-keyboards-targets-printers-firm-to-outsource-more-molding|title=Lexmark exits keyboards, targets printers: firm to outsource more molding|work=Plastics News|first=Clare|last=Goldsberry|date=December 4, 1995|access-date=2018-09-23}}</ref> When Lexmark discontinued keyboard production in April 1996, IBM continued producing buckling-spring Model M's in Scotland until 1999. Maxi Switch purchased assets for rubber-dome keyboards and the Lexmark Select-Ease Keyboard (model M15), including a buckling-spring switch patent.<ref>{{cite web|url=http://plasticsnews.com/article/19951211/NEWS/312119984/maxi-switch-obtains--rights-to-keyboards|title=Maxi Switch obtains rights to keyboards|work=Plastics News|first=Clare|last=Goldsberry|date=December 11, 1995|access-date=2018-09-23}}</ref> They continued to manufacture the IBM Enhanced Keyboard with [[TrackPoint]] II (model M13) in Mexico until 1998.

Some of Lexmark's keyboard manufacturing assets were also sold to a group of Lexmark employees, who formed [[Unicomp]]<ref name=verge /> whose basic version of the Model M was similar to part number 42H1292, first renamed 42H1292U and later the Customizer. There have been other configurations, including updated 104- and 105-key layouts; a [[Unix]] layout (where the [[Control key|Ctrl]], [[Caps Lock]], [[Esc key|Esc]], and [[tilde]] keys are transposed); models with integrated [[pointing stick]]s and [[trackball]]s; and [[point of sale|POS]]-specific models such as those with built-in [[magstripe]] readers. All used the press-fit controller characteristic of late Lexmarks.

Unicomp continued to use the original IBM machinery to produce Model Ms, leading to a gradual decline in quality as the tooling became worn. This, and various problems with their USB controllers<ref name=MTFAQ>{{cite web|url=http://catb.org/esr/faqs/model-m-troubleshooting.html|title=Model M Troubleshooting FAQ|access-date=2021-04-19}}</ref> helped keep a market for vintage Model Ms thriving. In 2020 Unicomp replaced its tooling and shipped a "New Model M" with noticeably improved<ref>{{Cite web |author1=Reece Bithrey |date=2021-08-03 |title=Unicomp New Model M review |url=https://www.pcgamer.com/unicomp-new-model-m-review/ |access-date=2022-11-12 |website=pcgamer |language=en}}</ref><ref>{{Cite web |last=Porter |first=Jon |date=2021-04-07 |title=Unicomp New Model M review: back to brilliant basics |url=https://www.theverge.com/22369731/unicomp-mechanical-keyboard-new-model-m-review-price |access-date=2022-11-12 |website=The Verge |language=en-US}}</ref> build quality that more closely resembles the classic 1391401 (though with a 104- or 103-key layout and USB); many older variants are no longer sold on Unicomp's website and some still on sale have been deprecated.