Model M keyboard

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IBM Model M Keyboard, Part no. 1391401, Manufactured 1989
IBM Model M Keyboard, Part no. 1391401, Manufactured 1989

The Model M keyboard is a class of computer keyboards manufactured by IBM, Lexmark and finally Unicomp, starting in the 1980s.

The many different variations of the keyboard have their own distinct characteristics, with the vast majority having a buckling spring key design and many having fully swappable keycaps. Model Ms have been prized by computer enthusiasts and heavy typists because of the tactile and auditory feedback resulting from a keystroke.

The Model M is also regarded as an extremely durable piece of hardware. Many units manufactured since 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.

Contents

[edit] History

Production for the original Model M began in 1984, and the keyboards were often bundled with new IBM computers in the 1980s. These keyboards were produced by IBM, made in the United States, and had part number 1391401. Until 1987, the keyboards featured a detachable AT cable; after that, they were bundled with a detachable PS/2 cable. Cables came in both 5 foot and 10 foot lengths.

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.

Unicomp Customizer 104 (UNI0P46) keyboard, manufactured April 25, 2005.
Unicomp Customizer 104 (UNI0P46) keyboard, manufactured April 25, 2005.

After that, a company called Unicomp bought the Model M design from Lexmark. The design, the same as the 42H1292 design but renamed 42H1292U, is still in production (as of 2007). Different configurations can be purchased from Unicomp, including updated 104-key layouts, a "Linux" model (where the Ctrl and Caps Lock keys are swapped), models with integrated Trackpoint pointing sticks, 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. Some PS/2 to USB adapters are unreliable because the Model M tends to draw more power than some adapters expect. However, Unicomp has recently added USB models to their lineup.

[edit] Design

Illustration from original U.S. Patent 4118611 , issued to IBM in 1978
Illustration from original U.S. Patent 4118611 , issued to IBM in 1978

The model people commonly refer to when they mention "Model M" is Part No. 1391401, which was by far the most common. This enhanced keyboard model included the patented buckling spring design and swappable keycaps, as well as the heavy and sturdy design of the Model Ms in general. This keyboard is widely praised as being exceedingly well-built, and indeed one of the longest lived (and loudest) computer components ever made. Part of this can be attributed to the fact that keyboard design has changed little in the past twenty years, while the designs of everything from PCs to monitors to mice have changed dramatically. The sturdy design (including heavy steel backplates and a high-quality, strong plastic frame) of the keyboard allows even the most abused to survive these years with ease. The various models of the keyboard had small differences, while keeping the style of the key mechanism that makes the boards unique. The 1391472 model, for example, does not have a separate number pad, rather it incorporates a number pad into the body of the main keys as many laptop keyboards do. Likewise, the early 1390120 series did not feature LED indicators for the locking keys.

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 not drain out, and would remain in the keyboard with potential to cause a short circuit. The 42H1292 design and post-1993 1391401's, 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.

[edit] Identification

The square aluminium badge on a 1390131 series keyboard from 1986
The square aluminium badge on a 1390131 series keyboard from 1986

All model M keyboards manufactured by either IBM or Lexmark feature an ID label indicating the individual serial number, the model designation, and the date the keyboard was minted. There are other more obvious ways to distinguish between the range, namely the type of badge featured on the top of the board. The first model M's (series 1390120 or 1390131) featured a square aluminium IBM badge in the top right corner. The next series (1391401) featured an oval, white IBM logo with grey lettering in the top left of the board. The later IBM manufactured boards and subsequent Lexmark boards of the early 90's (52G9658, 92G7453 or 42H1292) featured a similar oval badge to the 1391401, only with a grey background and blue lettering. Aside from these badging differences, the easiest way to distinguish between an IBM manufactured keyboard and a Lexmark or Unicomp board is the original IBM boards all feature a detachable cable.

[edit] Features by part number

Part Number Key Type Detachable Interface Drainage Channels Label Type/Position Manufacturer Dates of Manufacture Copyright Misc features
Key Caps Cable
1390120 Buckling Spring Yes Yes AT No Silver, Right Corner IBM 1986–1987 IBM Corp. 1984
1390131 Buckling Spring Yes Yes AT No  ? IBM 1986–1987, 1993 IBM Corp. 1984
1390133 Buckling Spring Yes Yes AT No Silver, Right Corner IBM  ?-1986-? IBM Corp. 1984 German QWERTZ layout
1391401 Buckling Spring Yes Yes AT or PS/2 No (Yes For 1993 and After) Grey (Blue 1993 and After), Left Corner IBM 1984–1994 IBM Corp. 1984
1391402 Buckling Spring Yes Yes PS/2 Yes ?  ? IBM UK  ?–1993–? IBM Corp. 1985 French AZERTY layout
1391403 Buckling Spring Yes Yes AT or PS/2 No  ? IBM 1986–? IBM Corp. 1985 German QWERTZ layout
1391405 Buckling Spring Yes Yes AT or PS/2 No  ? IBM 1986–? IBM Corp. 1985 Spanish QWERTY layout
1391406 Buckling Spring Yes Yes AT or PS/2 No Grey, left corner IBM ≤1988–1996 IBM United Kingdom UK 102-key variant
1391407 Buckling Spring Yes No PS/2 (or AT?) No ?  ? IBM  ?–1996-? IBM United Kingdom Icelandic 102-key
1391409 Buckling Spring Yes Yes PS/2 No Gray, left corner IBM 11/06/1992 IBM Corp. 1985 Norwegian 102-key
1391410 Buckling Spring Yes Yes PS/2 (or AT?) No  ? IBM UK  ?–1992–? IBM Corp. 1985 Portuguese 102-key
1391411 Buckling Spring Yes Yes PS/2 (or AT?) No  ? IBM UK  ?-1988–1992–? IBM Corp. 1985 Swedish 102-key
1391414 Buckling Spring Yes Yes PS/2 (or AT?) No  ? IBM UK  ?–1996–? IBM Corp. 1985 Dutch AZERTY layout
1391412 Buckling Spring Yes Yes PS/2 (or AT?) No  ? IBM UK  ?-1990-? IBM Corp. Swiss French QWERTZ layout
1391472 Buckling Spring Yes Yes AT or PS/2 No  ? IBM 1991 IBM Corp. 1984 Space saver; no numeric keypad or lights
1391506 Buckling Spring Yes Yes PS/2 No  ? IBM de Mexico 1990 IBM Corp. 1984
1394064 Buckling Spring Yes Yes PS/2 No  ? Lexmark  ?–1996–? Lexmark International, Inc. 1984
1395300 Buckling Spring No No PS/2 No  ? IBM 1990-1993 IBM Corp. 1984 Model M2; Shipped with IBM PS/1
1397599 Buckling Spring Yes Yes PS/2 Yes Gray, Left Corner IBM  ?–1993–? IBM Corp. 1984
42H1292, 82G2383, 92G7453, 92G7483 Buckling Spring Yes No PS/2 Yes  ? Lexmark 1993–1999 Lexmark International, Inc. 1984
51G8572 Buckling Spring Yes Yes PS/2 Yes oval blue, left corner Lexmark, IBM UK 1993-1996 IBM Corp. 1984/Lexmark International, Inc. 1984 Model M; shipped with IBM RS/6000; speaker on bottom of unit
52G9700 Buckling Spring No No PS/2 Yes  ? Lexmark 1993–1999 Lexmark International, Inc. 1984
71G4644 Dome switches No No PS/2 Yes  ? Lexmark Unknown Lexmark International, Inc. 1984
42H1292U Buckling Spring Yes No PS/2 Yes  ? Unicomp 1996–Present Unicomp, Inc. 1984 Optional AT/DIN adapter
82G3281 Buckling Spring No No PS/2 Yes  ? Lexmark 1994–1995 Lexmark International, Inc. 1984 White trackpoint, two connectors for keyboard and mouse
13H6705 Buckling Spring No No PS/2 Yes  ? Lexmark 1995–1998 Lexmark International, Inc. 1984 Black trackpoint, two connectors for keyboard and mouse
06H4173 Buckling Spring No No PS/2 Yes  ? Unicomp 1998–1999 Unicomp, Inc. 1984 Industrial PS/2 trackpoint, two connectors for keyboard and mouse

Note: The manufacture dates are approximate.

[edit] See also

[edit] References

[edit] External links

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