Model M keyboard

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

Unicomp Classic 104 (UNI044A) keyboard, manufactured April 23, 2012.

Comparison of different versions of IBM and Unicomp keyboards

The Model M keyboard, colloquially called a clicky keyboard, is a class of computer keyboard manufactured by IBM, Lexmark and Unicomp, starting in 1984. 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 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.^{[citation needed]} Many units manufactured since the mid-1980s are still in use today, while the computers and monitors of the day are obsolete. Unicomp, which now owns the rights to the design, continues to sell Model M keyboards. Recently, the keyboards have made a comeback among 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

Keycap in a French Model M

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, Greenock and Guadalajara. 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 cable; after that, they were bundled with a detachable PS/2 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, as well as the Microsoft Windows keys for the then-upcoming MS Windows 95 operating system.

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. 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" model (where the Ctrl and Caps Lock keys, and the ESC and tilde keys, are swapped), models with integrated Trackpoint pointing sticks or integrated trackballs, 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 still be purchased, original production models retain their value well among collectors as well as computer enthusiasts.^{[citation needed]}

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 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

Illustration from original U.S. Patent 4,118,611, 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 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 to monitors to mice have changed dramatically. The sturdy design (including heavy steel backplates and a strong plastic frame) of the keyboard allows even the most abused to survive for years. 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.

The Buckling Spring design gives the keyboard a unique 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; 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.^{[citation needed]}

There are some drawbacks to the Model M design. Because the keyboards are so heavy (over 3 lbs, heavier than some modern laptops) 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 or office) 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. The 42H1292 design and post-1993 1370477s and 1391401s, mostly made by Lexmark and Unicomp, include drainage channels to prevent this.

Identification

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 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

Part Number	Key Type	Detachable		Interf.	Drainage Channels	Label Type, Position	Maker	Years	Copyright	Miscellaneous Features
		Keycaps	Cable
71U4623 / 1378706 EC 1387530	Rubber Dome	No	No	PS/2	Yes	blue IBM and grey label, upper left corner	Lexmark	?–1995–?	Lexmark International, Inc. 1985	Removable keys, Speaker grill & holder w/o speaker, Swedish QWERTY-layout.
1370477	Buckling spring	No	Yes	PS/2	Yes	Blue, left corner	Lexmark	?–1995–?	Lexmark International, Inc. 1984
1370478	Buckling spring	Yes	Yes	PS/2	Yes	Blue, left corner	Lexmark	1993	Lexmark Int'l. Inc. 1984	M-5, trackball. Left and right click, and L/R "drag" buttons.
1397735	Buckling spring	Yes	Yes	PS/2	No	Oval, left corner, blank	IBM	?–1992–?	IBM Corp. 1984	US 101-key
1386085	Buckling spring	Yes	Yes	AT	No	Grey, left corner	IBM	1988	IBM Corp. 1984	English layout.
1388032	Buckling spring	Yes	Yes	PS/2	No{?}	Silver logo on black metal, right corner	IBM	1985	IBM Corp. 1984	English layout.
1389979	Buckling spring	Yes	Yes	AT	No	Silver, right corner	IBM	1986–87	IBM Corp. 1984	No LED lights for Num/Caps/Scroll lock. Swedish layout.
1390120	Buckling spring	Yes	Yes	AT or PS/2	No	Silver, right corner	IBM	1986–87	IBM Corp. 1984	No LED lights for Num/Caps/Scroll lock
1390131	Buckling spring	Yes	Yes	AT or PS/2	No	Silver, right corner	IBM	1986–88, 1993	IBM Corp. 1984
1390132	Buckling spring	Yes	Yes	AT or PS/2	No	Silver, right corner	IBM	1986–?	IBM Corp. 1986	French AZERTY layout
1390133	Buckling spring	Yes	Yes	AT or PS/2	No	Silver, right corner	IBM	?–1986–87	IBM Corp. 1984	German QWERTZ layout
1390148	Buckling spring	Yes	Yes	XT	No	Silver, right corner	IBM	?–1986–87	IBM Corp. 1984	No LED lights for Num/Caps/Scroll lock. German QWERTZ layout
1390639	Buckling spring	Yes	No	XT	Yes	Silver, right corner	IBM	?–1987–?	IBM Corp. 1985	Spanish QWERTY layout
1391401	Buckling spring	Yes	Yes	AT or PS/2	No (yes 1992 and after)	Grey (Blue 1992 and after), left corner	IBM	1986–96	IBM Corp. 1984
1391402	Buckling spring	Yes	Yes	PS/2	Yes ?	Grey (Blue 1992? and after), left corner	IBM UK	1991–96–?	IBM Corp. 1985	French AZERTY layout
1391403	Buckling spring	Yes	Yes (no 1995 and later)	AT or PS/2	Yes	Grey, left corner and also Blue, left corner	IBM UK, Lexmark International	1986–97	IBM Corp./Lexmark International Inc. 1985	German QWERTZ layout
1391404	Buckling spring	Yes	Yes	AT or PS/2	No	Grey, left corner	IBM UK	1986–?	IBM Corporation (no year on label)	Italian QWERTY layout
1393395	Buckling spring	Yes	Yes	PS/2	No	Grey, left corner	IBM UK	1985–?	IBM Corporation 1985	Italian QWERTY layout
1391405	Buckling spring	Yes	Yes	AT or PS/2	No	Black/Blue, left corner	IBM	1986–?	IBM Corp. 1985	Spanish QWERTY layout
1391406	Buckling spring	Yes	Yes	AT or PS/2	No	Grey, left corner	IBM	≤1985–99	IBM United Kingdom	UK 102-key variant
1391407	Buckling spring	Yes	Yes	PS/2	Yes	Grey, left corner	IBM	?–1994–96–?	IBM United Kingdom	Danish/Icelandic 102-key
1391409	Buckling spring	Yes	Yes	PS/2	No	Gray, left corner	IBM	1987?–94?	IBM Corp. 1985/Lexmark Int. 1985	Norwegian 102-key
1391410	Buckling spring	Yes	Yes	PS/2 (or AT?)	No	Gray, left corner	IBM UK	?–1992–?	IBM Corp. 1985	Portuguese 102-key
1391411	Buckling spring	Yes	Yes	AT or PS/2	No	Gray/blue, left corner	IBM UK	?–1987–97–?	IBM Corp. 1985	Swedish 102-key
1391414	Buckling spring	Yes	Yes	PS/2	No	Gray, left corner	IBM UK	?–1996–?	IBM Corp. 1985	Belgian AZERTY layout
1391412	Buckling spring	Yes	Yes	PS/2	No	Gray, left corner	IBM UK	1987–96	IBM Corp.	Swiss French/German QWERTZ layout, 102-key
1391472	Buckling spring	Yes	Yes	AT or PS/2	No	Gray, left corner	IBM	1987–91	IBM Corp. 1984	Space saver; no numeric keypad or lights
1391506	Buckling spring	Yes	Yes	PS/2	No	Gray/blue, left corner and also grey left corner	IBM de Mexico	1990	IBM Corp. 1984	Spanish QWERTY layout
1391511	Buckling spring	Yes	Yes	PS/2	No	Blue, left corner	IBM UK	1990–93	IBM Corp. 1985	Dutch 102-key
1392565	Buckling spring	Yes	No	8P5C (RJ-45)	Yes	Grey, left corner	Lexmark (for IBM)	?–1995	Lexmark International, Inc. 1984	Keyboard for terminals such as IBM 3151. Line drawing characters on the numeric keypad. "Page Up"/"Page Down" replaced with "Clear"/"Erase EOF". Bottom row consists of "Ctrl", "Reset", spacebar, "Ctrl", "Send". Speaker grill on bottom of unit.
1392934	Buckling spring	Yes	Yes	AT or PS/2	No	Gray, left corner	IBM	?–1987–90–?	IBM Corp. 1984	Space saver; no numeric keypad or lights
1393464	Buckling spring	Yes	Yes	PS/2	No{?}	Grey, left corner	IBM	?–1989–92–?	IBM Corp. 1984	Same as 1391401, with special key-caps: Used for airline reservations
1393669	Buckling spring	Yes (no after ????)	Yes (no after 1994)	AT or PS/2	partial after 1995, yes after ????	Gray label, left corner / Blue label, left corner / IBM sign, below LEDs	Lexmark UK, IBM UK / Unicomp	198?–200?	Lexmark International Inc. 1985 / IBM Corp. 1985 / Unicomp 1996	Slovenian / Croatian (former YU) QWERTZ layout; with or without speaker grill on bottom of unit
1394064	Buckling spring	Yes	Yes	PS/2	No	?	Lexmark	?–1996–?	Lexmark International, Inc. 1984
1394540	Buckling spring	Yes	Yes	PS/2	No	Gray, left corner	IBM	1990–91?	IBM Corp. 1984	Made for IBM RS/6000 computer. Contains real speaker.
1398601	Buckling Spring	Yes	Yes	AT 5-din or Ps/2	Yes	Lexmark logo, left corner	Lexmark	?–1993–?	Lexmark Int'l Inc 1984
1394542	Buckling spring	Yes	Yes	PS/2	Yes	Gray/blue, left corner	IBM UK	1991–94?	IBM Corp. 1985	German QWERTZ layout
1394545	Buckling spring	Yes	Yes	PS/2	No	Gray/Blue, left corner	IBM UK, Lexmark	1990–96?	IBM Corp. 1985 / Lexmark International Inc. 1985	Made for IBM RS/6000 computer. Contains real speaker. Swedish/Finnish 102-key QWERTY layout.
1394958	Buckling spring	Yes	Yes	PS/2	Yes	Silver on black, left corner	IBM UK	?–1998–?	IBM Corp. 1985	German QWERTZ, dark gray industrial version
1394966	Buckling spring	Yes	Yes	PS/2	?	Silver on black, left corner	IBM UK	1992	IBM Corp. 1985	Swedish 102-key, dark gray industrial version
1395300	Buckling spring	No	No	PS/2	No	Blue, top right right	IBM	1990–93	IBM Corp. 1984	Model M2; Shipped with IBM PS/1
1396790	Buckling spring	Yes	Yes	PS/2	Yes (no 1991)	Grey (Blue 1992 and after), left corner	IBM	?–1991–95?	IBM Corp. 1985	Made in UK by IBM; North American layout
1397003	Buckling spring	Yes	Yes	PS/2	?	Blue, top left	IBM	?–1993–99?	IBM Corp. 1985	Made in UK by IBM; German QWERTZ; 122 Keys
1397000	Buckling spring	Yes	Yes	PS/2	?	Blue, top left	Lexmark (for IBM)	?	Lexmark International, Inc. 1984	122-key terminal emulation keyboard: Home/Rule key with arrow keys in a "plus" layout, 24 function keys, 10-key left cluster with terminal commands (Attn, Clear, Pause, ErEOF, etc.)
1397599	Buckling spring	Yes	Yes	PS/2	Yes	Gray, left corner	IBM	?–1993–?	IBM Corp. 1984
1397681	Buckling spring	No	Yes	PS/2 (or AT?)	Yes	Gray, left corner (later Blue)	IBM	?–1991–93–?	IBM Corp. 1984	Space saver; no numeric keypad or lights
1399625	Buckling spring	Yes	No	PS/2	Yes	Blue, left corner	Lexmark, IBM UK	?–1994–?	Lexmark International Inc. 1985	Terminal keyboard; speaker grill on bottom of unit; no lights
13H6705	Buckling spring	No	No	PS/2	Yes	Silver, left corner	Lexmark, Maxi Switch	1994–98	Lexmark International, Inc. 1984, or None (on Maxi Switch models)	Trackpoint, two connectors for keyboard and mouse, the only Model M to come in Black
42H1292, 92G7453, 92G7483	Buckling spring	Yes	No	PS/2	Yes	Blue, left corner	Lexmark, IBM UK	1993–99	Lexmark International, Inc. 1984
42H1292U	Buckling spring	Yes	No	PS/2	Yes	Blue, left corner	Unicomp	1996–	Unicomp, Inc. 1984	Optional AT/DIN adapter
51G8572	Buckling spring	Yes	Yes	PS/2	Yes	Gray/Blue, left corner	IBM, Lexmark, IBM UK	1993–96	IBM Corp. 1984, Lexmark International, Inc. 1984	Model M; shipped with IBM RS/6000; speaker on bottom of unit
52G9658	Buckling spring	Yes	No	PS/2	Yes	Blue, left corner	Lexmark	?–1993–?	Lexmark International, Inc. 1984	Model M; speaker grill on bottom of unit
52G9700	Buckling spring	Yes	No	PS/2	Yes	Blue, left corner	Lexmark	1993–99	Lexmark International, Inc. 1984	Model M; speaker grill on bottom of unit
70G8638	Rubber Dome	No	No	PS/2	Yes	Square, top right	Lexmark	?–1994–?	Lexmark International. Inc. 1984	Speaker grill on bottom of unit, silkscreen keycaps
71G4621	Dome switches	Yes	No	PS/2	Yes	Blue, left corner	Lexmark (for IBM)	?–1996–?	Lexmark International, Inc. 1984	Danish QWERTY layout
71G4622	Dome switches	No	No	PS/2	Yes	Blue, left corner	Lexmark (for IBM)	?–1995–?	Lexmark International, Inc. 1984	Dutch QWERTY layout, 1378705, EC1391461
71G4625	Dome switches	No	No	PS/2	Yes	Grey, left corner	Lexmark (for IBM)	?–1993–96–?	Lexmark International, Inc. 1985	German QWERTZ layout
71G4630	Dome switches	No	No	PS/2	Yes	Blue, left corner	Lexmark (for IBM)	?–1994–?	Lexmark International, Inc. 1984	Italian QWERTY layout
71G4643	Dome switches	Yes	No	PS/2	Yes	Blue, left corner	Lexmark	?–1995–?	Lexmark International, Inc. 1985
71G4644	Dome switches	No	No	PS/2	Yes	Blue, left corner	Lexmark	?–1993–95–?	Lexmark International, Inc. 1984
8131276	Buckling spring	No	No	RJ25	Yes	Blue, Upper-right corner	IBM UK	?–1997	IBM Corp.
82G2383	Buckling spring	Yes	No	PS/2	Yes	Blue, left corner	Lexmark	1993–99	Lexmark International, Inc. 1984
82G3281	Buckling spring	No	No	PS/2	Yes	?	Lexmark	1994–95	Lexmark International, Inc. 1984	White trackpoint, two connectors for keyboard and mouse
82G3295	Buckling spring	Yes	No	PS/2	Yes	Blue "IBM", top left corner	Lexmark	?–1995–?	Lexmark International, Inc. 1984
06H4173	Buckling spring	No	No	PS/2	Yes	?	Unicomp	1998–99	Unicomp, Inc. 1984	Industrial PS/2 trackpoint, two connectors for keyboard and mouse
UB40R46	Buckling spring	No	No	PS/2	Yes	?	Unicomp	?–	Unicomp, Inc. 1984	104 key, customizable layout.
UB4044A	Buckling spring	No	No	USB	Yes	None	Unicomp	?–	Unicomp, Inc. 1984	104 key, customizable layout (USB version).
02K3817	Buckling spring	Yes	No	PS/2	Yes	None	Unicomp	?–	Unicomp, Inc. 1984	German layout unicomp keyboard
UNI0T56	Buckling spring	No	No	PS/2	Yes	None	Unicomp	?–2003–?	?	122 key, laid out for use with PC/5250 emulators; produces standard 101-key scancodes with keys that are not present on a standard keyboard mapped to standard keys with modifiers (e.g., F24 appears to the PC as shift+F12)
1386887	Buckling spring	Yes	No	Terminal DIN-5	No	Square metal, black on silver. Upper right.	IBM	?–1986–?	IBM Corp. 1985	122 key 3179 terminal keyboard
1389194	Buckling spring	Yes	No	Terminal DIN-5	No	Square metal, black on silver. Upper right.	IBM	?–1986–?	IBM Corp. 1984	122 key 3179/3192 terminal keyboard, APL keycaps
1369182	Buckling spring	No	No	PS/2	Yes	"DELL" logo, grey on white, upper left corner	Lexmark "Made in the USA"	?–1993–?	Lexmark International, Inc. 1984	Latin American QWERTY Layout
1369050	Buckling spring	No	No	PS/2	Yes	"DELL" logo, grey on white, upper left corner	Lexmark "Made in the USA"	?–1995–?	Lexmark International, Inc. 1984	US Standard QWERTY Layout
Part Number	Key Type	Detachable		Interface	Drainage Channels	Label Type/Position	Manufacturer	Dates of Manufacture	Copyright	Misc features
		Key Caps	Cable

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

External links

• PC keyboard, Unicomp  – current Model M manufacturer.
• Clicky keyboards  – distributor of refurbished and never used Model M keyboards.
• "Inside the World's Greatest Keyboard", PC World .
• Care and feeding of an IBM Model M keyboard, Preater  – a Model M restoration guide.
• Cramer, Ryan, "The IBM Model-M Keyboard", Timeless Tools, RCD .