The Model M keyboard is a class of computer keyboards manufactured by IBM, Lexmark and finally Unicomp, starting in the 1980s.
The Model M was considered a class of keyboards rather than a specific model, as the many different models of the keyboard had their own distinct characteristics. Model Ms have been prized by computer enthusiasts and heavy typists, because most models included convenient fully swappable keycaps and a sturdy and reliable buckling spring key design. The Model M is also remembered for its overall heavy and sturdy design, which allowed the keyboard to survive far longer periods of time, use, and abuse than practically any other personal computer component ever manufactured.
Many Model Ms manufactured in the mid 1980s are still in use today, while the computers and monitors of the day have long since been thrown out, recycled, or retired to museums.
In 1991, IBM divested a number of its hardware manufacturing operations to form Lexmark; the Model M keyboard group was subsequently sold to Lexmark in 1993. The Lexmark-produced keyboards are identifiable by the back label, which clearly says "Manufactured for IBM by Lexmark", and most had part number 42H1292. Widely regarded as somewhat inferior in build quality to the original Model M, the 42H1292 also featured internal drainage channels designed to minimize damage in case of a spill. These keyboards were produced until 1996.
After that, a company called Unicomp bought the Model M design from Lexmark. The design, the same as the 42H1292 design, is still in production. Different configurations can be purchased from Unicomp, including updated 104-key layouts, a "Linux" model (where the Ctrl and Caps Lock keys are swapped), and POS-specific models, such as those with built-in magstrip readers. Although current Unicomp models may be purchased for roughly 50 USD, original production models retain their value well among collectors as well as computer enthusiasts, and it is not uncommon to see them selling for upwards of 150 USD for a single, used unit.
There are numerous flavors of the Model M, but many of them are exceedingly rare. Sometimes it may be problematic to get them to communicate properly with a modern computer. A PS/2 to USB adapter would be necessary for computers without PS/2 ports, and the AT Model Ms additionally require an AT to PS/2 adapter.
Most fans of the Model M especially prize its feel and sound. Unlike the common (but cheaper) dome switch design in use today, the Model M's buckling spring design gives users obvious tactile (a distinctive resistance as the keys are depressed) and aural (a characteristic, loud "click-clack"ing) feedback while typing, in ways similar to that of the keyboards of the long-running IBM Selectric typewriter line. In addition, the Model M keyboard is less susceptible to dirt and wear and tear; while dirt will interfere with proper operation of a dome switch keyboard, the design of a buckling spring keyboard is such that any dirt that falls between the cracks usually fails to make it into the spring mechanism. Failure of the mechanism to operate properly would require a large amount of accumulation, which is unlikely to occur.
There are some drawbacks to the Model M design, however. Because the keyboard is so heavy, it is not as portable as many modern keyboards. The keys are very noisy and would be inappropriate in a situation (such as a public library) where noise is an issue. Also, any liquids spilled on the keyboard would cause a short circuit, immediately rendering the keyboard inoperable. The 42H1292 design, mostly made by Lexmark and Unicomp, includes drainage channels to prevent this, though it is done at the slight expense of the keyboard's quality.
| Model | Key Type | Key Caps | Cable | Drainage Channels | Manufacturer | Dates of Manufacture | Copyright |
| 1390120 | Buckling Spring | Separate | Detachable SDL to AT | No | IBM | 1986–1987 | IBM Corp. 1984 |
| 1390131 | Buckling Spring | Separate | Detachable SDL to AT | No | IBM | 1986–1987, 1993 | IBM Corp. 1984 |
| 1391401 | Buckling Spring | Separate | Detachable SDL to AT or PS/2 | No (yes for 1391401 made 1993 and after) | IBM | 1986–1994 | IBM Corp. 1984 |
| 1391402 (french AZERTY layout) | Buckling Spring | Separate | Detachable SDL to PS/2 | Yes ? | IBM UK | 1993 (at least) | IBM Corp. 1985 |
| 1391403 | Buckling Spring | Separate | Detachable SDL to AT or PS/2 | No | IBM | 1986–? | IBM Corp. 1985 |
| 1391406 | Buckling Spring | Separate | Detachable SDL to AT or PS/2 | No | IBM | <=1988-1996 | IBM United Kingdom |
| 1391411 (Swedish 102) | Buckling Spring | Separate | Detachable SDL to PS/2 (or AT?) | No | IBM UK | ?-1992-? | IBM Corp. 1985 |
| 1391472 | Buckling Spring | Separate | Detachable SDL to AT or PS/2 | No | IBM | 1991 | IBM Corp. 1984 |
| 1391506 | Buckling Spring | Separate | Detachable SDL to PS/2 | No | IBM de Mexico | 1990 | IBM Corp. 1984 |
| 42H1292, 82G2383, 92G7453 | Buckling Spring | Separate | Attached PS/2 | Yes | Lexmark | 1993–1999 | Lexmark International, Inc. 1984 |
| 52G9700 | Buckling Spring | Part of Keys | Attached PS/2 | Yes | Lexmark | 1993–1999 | Lexmark International, Inc. 1984 |
| 71G4644 | Dome switches | Part of Keys | Attached PS/2 | Yes | Lexmark | Unknown | Lexmark International, Inc. 1984 |
| 42H1292U | Buckling Spring | Part of Keys | Attached PS/2, optional AT/DIN adapter | Yes | Unicomp | 1996 - Present | Unicomp, Inc. 1984 |
| 82G3281 (white trackpoint) | Buckling Spring | Part of Keys | Attached PS/2, two connectors for keyboard and mouse | Yes | Lexmark | 1994-1995 | Lexmark International, Inc. 1984 |
| 13H6705 (black trackpoint) | Buckling Spring | Part of Keys | Attached PS/2, two connectors for keyboard and mouse | Yes | Lexmark | 1995-1998 | Lexmark International, Inc. 1984 |
| 06H4173 (industrial ps/2 trackpoint) | Buckling Spring | Part of Keys | Attached PS/2, two connectors for keyboard and mouse | Yes | Unicomp | 1998-1999 | Unicomp, Inc. 1984 |
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It uses material from the
"Model M Keyboard".
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