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The Model M keyboard is a class of computer keyboard
Computer keyboard
In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...

s manufactured by IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

, Lexmark
Lexmark
Lexmark International, Inc. is an American corporation which develops and manufactures printing and imaging products, including laser and inkjet printers, multifunction products, printing supplies, and services for business and individual consumers...

 and Unicomp
Unicomp
Unicomp is a manufacturer of computer keyboards and keyboard accessories based in Lexington, Kentucky. The company was founded in April 1996 when they purchased the license to the buckling-spring keyboard technology from Lexmark International, Inc.Unicomp's product line consists mostly of...

, starting in 1984. The many different variations of the keyboard have their own distinct characteristics, with the vast majority having a buckling spring
Buckling spring
A buckling spring is a type of keyswitch mechanism, popularized by IBM's keyboards for the PC, PC/AT, 5250/3270 terminals, PS/2, and other systems. It was used by IBM's Model F keyboard, and the more common Model M. It is described in ....

 key design and many having fully swappable keycap
Keycap
A keycap is a small plastic cover placed over the keyswitch of a computer keyboard. Keycaps are illustrated to indicate the key function or alphanumeric character they correspond to...

s. Model M keyboards 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 a timeless and durable piece of hardware. Many units manufactured since the mid 1980s are still in use today, while the computers and monitors of the day are obsolete. Unicomp
Unicomp
Unicomp is a manufacturer of computer keyboards and keyboard accessories based in Lexington, Kentucky. The company was founded in April 1996 when they purchased the license to the buckling-spring keyboard technology from Lexmark International, Inc.Unicomp's product line consists mostly of...

, which now owns the rights to the design, continues to sell Model M keyboards. Recently, the keyboards have made a comeback amongst writers and computer techs. Unicomp has had difficulty making them profitable because they rarely break, and most retailers will not stock such an expensive keyboard.

History

The Model M was designed to be a more cost effective keyboard than the Model F keyboards it replaced. Production for the original Model M began in 1985, and the keyboards were often bundled with new IBM computers in the 1980s. These keyboards were produced by IBM in their plants in Lexington
Lexington, Kentucky
Lexington is the second-largest city in Kentucky and the 63rd largest in the US. Known as the "Thoroughbred City" and the "Horse Capital of the World", it is located in the heart of Kentucky's Bluegrass region...

, Greenock
Greenock
Greenock is a town and administrative centre in the Inverclyde council area in United Kingdom, and a former burgh within the historic county of Renfrewshire, located in the west central Lowlands of Scotland...

 and Guadalajara
Guadalajara
Guadalajara may refer to:In Mexico:*Guadalajara, Jalisco, the capital of the state of Jalisco and second largest city in Mexico**Guadalajara Metropolitan Area*University of Guadalajara, a public university in Guadalajara, Jalisco...

. The most common Model M variant is the part number 1391401, which was the keyboard of the IBM PS/2. Until 1987, the keyboards featured a detachable AT
IBM Personal Computer/AT
The IBM Personal Computer AT, more commonly known as the IBM AT and also sometimes called the PC AT or PC/AT, was IBM's second-generation PC, designed around the 6 MHz Intel 80286 microprocessor and released in 1984 as machine type 5170...

 cable; after that, they were bundled with a detachable PS/2
PS/2 connector
The PS/2 connector is a 6-pin Mini-DIN connector used for connecting some keyboards and mice to a PC compatible computer system. Its name comes from the IBM Personal System/2 series of personal computers, with which it was introduced in 1987...

 cable. Cables came in both 5- and 10-foot lengths (1.5 and 3 metres). From about 1994 onwards, the majority of Model Ms were manufactured with non-detachable cables to cut down manufacturing costs.

In March 1991, IBM divested a number of its hardware manufacturing operations, including keyboard manufacturing, to the investment firm Clayton & Dubilier, Inc. in a leveraged buyout to form Lexmark International, Inc. The Model M keyboard continued to be produced by Lexmark in the United States and Mexico, and IBM in Scotland with IBM being Lexmark's major customer. Many of the keyboards had IBM assembly part numbers 52G9658, 52G9700, 82G2383, 42H1292, and others. Because of pricing pressures, many of these Model M keyboards were manufactured with a new lower-cost keyboard design to improve its competitiveness in the keyboard business. Lighter weight plastic, integrated keyboard cable, and uniform print color on the keys were some of the changes made.

In 1996, Lexmark's contract to produce keyboards for IBM ran out, and Lexmark sold the keyboard manufacturing equipment to some of their employees, who formed Unicomp
Unicomp
Unicomp is a manufacturer of computer keyboards and keyboard accessories based in Lexington, Kentucky. The company was founded in April 1996 when they purchased the license to the buckling-spring keyboard technology from Lexmark International, Inc.Unicomp's product line consists mostly of...

. The Model M, similar to part number 42H1292 but first renamed 42H1292U and subsequently the "Customizer", is still in production. Different configurations can be purchased from Unicomp, including updated 104/105-key layouts, a "Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

" model (where the Ctrl and Caps Lock keys, and the ESC and tilde keys, are swapped), models with integrated Trackpoint pointing stick
Pointing stick
The pointing stick is an isometric joystick used as a pointing device . It was invented by research scientist Ted Selker...

s or integrated trackball
Trackball
A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a cursor...

s, and POS-specific models, such as those with built-in magstripe readers. When Lexmark stopped producing the Model M designs for IBM, IBM continued manufacture in their Scottish plant, and subcontracted production of the Model M13 Trackpoint II keyboard to Maxiswitch. Production of Model Ms by these companies ended in 1999 and 1998 respectively. Although current Unicomp models may be purchased for roughly 79 USD
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....

, 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 variations 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
Universal Serial Bus
USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....

 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. In response to these complaints, Unicomp added USB models to their lineup.

Design

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 well-built. Evidence of this can be seen in the fact that keyboard design has changed little in the past twenty years, while the designs of everything from PCs
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

 to monitors
Computer display
A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...

 to mice have changed dramatically. The sturdy design (including heavy steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 backplates and a high-quality, strong plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

 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, 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") feedback. Many users report that they can type faster and more-accurately on the Model M than other keyboards.

In addition, the Model M keyboard is less susceptible to dirt and wear and tear
Wear and tear
Wear and tear is damage that naturally and inevitably occurs as a result of normal wear or aging. It is used in a legal context for such areas as warranty contracts from manufacturers, which usually stipulate that damage due to wear and tear will not be covered.Wear and tear is a form of...

; 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. Because the keyboard is so heavy, it is not as portable as many modern keyboards. The keys are noisy enough to be inappropriate in a location (such as a public library
Library
In a traditional sense, a library is a large collection of books, and can refer to the place in which the collection is housed. Today, the term can refer to any collection, including digital sources, resources, and services...

) where noise is an issue. Also, liquids spilled on the keyboard do not drain out, and remain in the keyboard with potential to cause a short circuit
Short circuit
A short circuit in an electrical circuit that allows a current to travel along an unintended path, often where essentially no electrical impedance is encountered....

. The 42H1292 design and post-1993 1370477s and 1391401s, mostly made by Lexmark and Unicomp, include drainage channels to prevent this.

Identification

All Model M keyboards manufactured by either IBM or Lexmark feature an ID label on the underside indicating the assembly part number, individual serial number, and date the keyboard was manufactured. There are other more obvious ways to distinguish between the range, namely the type of badge featured on the top of the keyboard. The first model Ms (part numbers 1390120 or 1390131) featured a square aluminum IBM badge in the top right corner. Part number 1391401 featured an oval, white IBM logo with grey lettering in the top left of the board. The later IBM manufactured keyboards and subsequent Lexmark keyboards of the early 1990s (IBM assembly part numbers 1370477, 52G9658, 52G9700, 92G7453, 82G2383, 42H1292, and others) featured a similar oval badge to part number 1391401, but instead with a grey background and blue lettering.

Features by part number



Note: The manufacture dates are approximate. Click "Show" to display the uncollapsed table.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
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