Model M keyboard
The Model M keyboard called a computer keyboard genus, the "Model M" goes back to the millions produced 1984-1999 IBM keyboard. The Model M keyboard was designed by IBM for their IBM personal computer and got the "Enhanced Personal Computer Keyboard" key layout as a further development of the 84-key AT keyboard design and the IBM 122- key terminal keyboard design. Originally produced by IBM itself in its own factories, were later Model M keyboards from Lexmark, and manufactured to a lesser extent from other manufacturers, in order.
The vast majority of keyboards in this series is characterized by buckling springs and fully interchangeable keyboard caps, however, there are many different variants of this keyboard with partially differing characteristics. The Model M keyboards are very popular because of their precise pressure point and the associated tactile feedback for frequent writers. Furthermore, the Model M series is well known for its robustness: Many of these keyboards that are in use since the mid-1980s, still work and are still in use - in contrast to most other computer hardware from that time. Also, the Model M made the IBM " Enhanced" key layout in the PC area which is popular to this day, except for minor modifications and extensions used. Currently the company produces and sells Unicomp Model M keyboards with buckling spring keys under his own name.
Technical Details
A salient feature of the Model M keyboards is the "hard" keystroke with a pressure point (approx. 70 g key force ), in which the opposing force abruptly decreases (to about 50 g key force ). This tactile feedback to the user about the successful key operation is generated. This positive feature is the buckling spring technology (English buckling -spring technology) realized that in addition also a characteristic Tastaturanschlagton? / I produced (acoustic feedback). Through this significant twofold Feedback experienced writers can unnecessarily by pressing the button to the bottom and thus avoid potentially tap a little faster and error free. Located under each key of this a coil spring from buckling under the pressure finger of the operator, thereby triggering a hammer, compresses two electrically conductive plastic films / membranes, and thus produces the switching contact.
The keyboards are unusually heavy by today's standards, but also stable, which is achieved by a steel plate as an internal pad. Often the key caps are removable for easy cleaning, as well as the labeling as a permanent dye sublimation printing ( " dye sublimated " ) deep into the plastic cap. Also the keyboard caps made from high quality PBT plastic material are made and thus more resistant to wear and yellowing than other materials such as ABS ( common material in current keyboards). The IBM Model M keys were specified for 25 million keystrokes, which would mean at a prolific writer with 100 strokes a minute, eight- hour day, 250 working days, even for the button on the commonly used "E" more than 10 years service life. The motivation for this complicated technology was that at the time of the introduction of the Model M PCs and terminals even with high-quality typewriters ( esp. the IBM Selectric ) and competed users to switch should be simplified to the new technology with a like typing feel.
Using the model M and the IBM "Enhanced personal computer keyboard " layout has been introduced in the PC field, and had, in contrast to the previous IBM PC keyboard (such as the AT keyboard ), a significantly altered and extended key layout. For example, the F11 and F12 function keys and a remote block next to the numeric keypad have been added, important keys have been enlarged (Shift and Return) or arranged ergonomically on the keyboard. It is believed that with the " Enhanced " keyboard layout, IBM tried to konsolideren his keyboard production was (each with international variants) split between multiple terminal keyboard layouts and the PC keyboard layout. A keyboard design should be able to cover both use cases, for example, the terminals with terminal emulators. For IBM took over for the "Enhanced " -101/102-Tastenlayout primarily the terminal basic design ( only 12 instead of 24 F- keys) and from the AT keyboard LEDs. Also, the " Enhanced " design was typically 102- tastigen international keyboard layouts (like the German "AZERTY " ) integrated as assembly of the 101- tastigen basic design, which also helped reduce costs.
However, there are some disadvantageous properties of the model M-design. Model M keyboards are quite heavy (about 2.5 kg in the first generation ) and therefore less portable. For volume - sensitive areas, such as libraries or large offices, they are suited by the loud switching noise limited. Although keyboards are very robust against dry dirt, liquids remain in the keyboard stand and glue the membranes (later mitigated by drainage channels ). By a " 2 Key Roll Over" design can in the worst case scenario only two simultaneously pressed keys are correctly identified on scan codes ( However, through clever design all standard 3-button combinations were seized ). The implementation of scan codes is done by a Hitachi or Motorola 6805 microcontroller. Finally, also the model M has a film-based setup, no mechanical switches per key and is therefore not a true "mechanical keyboard " ( even if it is in many features such as a behavior ). It is also difficult to maintain and repair because the case with non-standard 7/32 inch ( 5.5 mm metric) hex bolts and the inner board is closed by plastic rivets. If the rivet heads are removed to have come to the keyboard slides they are inevitably replaced by consuming nuts and bolts. Also the Model- M more power than current keyboards requiring significantly usual, about 120 mA and 40 mA for the three LEDs. This becomes a problem when a passive PS2 - USB interface adapter is used which does not expect such a load or the USB 500 mA possible not sufficient for reliable operation. However, there are active PS2 -USB converter that works with the Model- M; also took later Unicomp Model Ms with native USB interface in the program.
History
The Model M was a cost- efficient replacement of the Model F designs ( used eg in AT keyboard ) developed. As the core of the Model M is a membrane - buckling spring key design was chosen ( engl. Membrane Buckling Spring), a patented IBM style. The precursor patent for capacitive buckling spring key ( as used in the Model F) had IBM employee Richard Hunter Harris on August 30, 1977 under the name buckling spring torsional snap actuator and the patent number 4,118,611 in the American USPTO requested that the patent was granted on October 3, 1978. based thereon Patent US4528431 that for the membranes - buckling spring key for the model M ( Rocking switch actuator for a low force membrane contact switch) has issued July 9, 1985.
The production for the original Model M was added in 1985 and the keyboards were often sold through the entire 1980s in a bundle with new IBM computers. These keyboards were manufactured by IBM in its factories in Lexington (USA), Greenock (Scotland) and Guadalajara ( Mexico). By 1987, the keyboard had a absteckbares AT cable, after which they were provided with a absteckbaren PS/2-cable. The flexible spiral cable, there were 5 and 10 feet long (about 1.5 to 3 m). It was produced in greater numbers three color options: white-beige ( undyed ), industrial gray and black.
In March 1991, IBM began its hardware parts manufacturing plants to the investment firm Clayton & Dubilier outsource to Lexmark International to set up, including the keyboard production. The Model M keyboard was further made by Lexmark ( for IBM in particular ) in the United States and Mexico and IBM even in Scotland. Many of these keyboards have the IBM production numbers 52G9658, 52G9700, 82G2383, 42H1292.
The price of a Model -M ( with Track Point) in 1993 was $ 159, which equals $ adjusted for inflation in 2012 about 253 ( about 193 € end of 2012).
As of 1994, the majority of Model Ms was easier to manufacture to increasing price pressure to meet the market: the simplifications included lighter-weight plastic parts, a fixed cable, a thinner steel plate and only one color keycap. Small improvements were also made , however, such as the adding of liquid flow channels on the housing bottom. Overall, changes in the structure were carried out in four generations in the classical model M. The model most widely produced variant of M, denoted by the production number 1391401, is a U.S. English keyboard with key layout for the IBM PS / 2 interface in white- beige.
On 3 October 1995, the buckling spring Patent US4118611 ran out, the patent for the membrane - kink spring button on 9 July 2002, each 17 years after the grant. The last patent, the Model M in question was probably 2004.
1996 ran from Lexmark's contractual obligation on the production of keyboards for IBM and Lexmark discontinued the production. However, Lexmark sold the production machines and patents on some of their employees, which Unicomp founded in Lexington and production continued led. The Unicomp variant of the Model M, which is similar to the IBM 42H1292 model and was first described as 42H1292U and later referred to as the " Customizer ", is still produced (as of 2013). As Lexmark finished production for IBM, IBM made on keyboards in their own remaining Scottish factory and awarded the production of the M13 Trackpoint II keyboard model to Maxi Switch. The production by Maxi Switch ended in 1998, by IBM in 1999.
Remained the only model M- producer from the 2000s led Unicomp modernized versions with native USB port, as well as enhancements to the IBM Enhanced keyboard layouts for Microsoft Windows which had become customary now buttons.
Reception
The contemporary reception was overwhelmingly positive, even if the AT PC keyboard significantly altered keyboard layout was criticized in comparison to the previous 84-key. For example, John C. Dvorak InfoWorld criticized in 1986, although the introduced as "Enhanced Personal Computer Keyboard" IBM new layout completed but positively with "It's still the best " feeling "keyboard in the world. " The system introduced by IBM " Enhanced" -101/102-Tasten-Layout prevailed with the Model- M in the PC sector and defined all of the following PC keyboard layouts until today, which only gradually different variants are typically of this layout.
The IBM Model M was retrospectively praised by many recipients as timeless and enduring hardware design and also referred to as the "Best Keyboard ever built ". For example, Eric S. Raymond outed himself as a great model M fan and called it a " classic".
Also, the model M is still considered a reference against which to measure current mechanical keyboards or the design oriented, such as tactile Cherry MX Green button in the introduction.
An extensive community exists at enthusiasts dedicated to the behavior, care and Adaptation ( Modding ) Model- Ms busy. Typical modifications start with simple color adjustments on replace the plastic rivets by bolts on noise reduction up to complete rebuilds of the case eg in the steampunk style.
Although Unicomp continue to produce replicas, the original IBM and Lexmark variants were able to get their value under Keyboard enthusiasts and are used trading at prices as new high-quality keyboards (about 80 € ). In the 14 years with IBM -driven production of the Model M is a large number of variants were produced, with some variants are now extremely rare and valuable.
The mid-2000s, some commentators spoke in connection with the Unicomp buckling spring keyboards of a (small ) comeback of the Model M keyboard.
Functions by Item Number
Gallery
A model M of 1994, Part No. 1394542 with blue logo at the top left of Lexmark production. German 102-key QWERTY layout.
Back of a Model M 1994, Item No. 1394542 Lexmark production. Can be seen on top of the keyboard, the four unusual and deeply recessed 5.5 mm hex screws. In the middle of the identification label.
Label with part number and serial number 1994, Art No. 1394542 Lexmark production. Listed at the bottom of the signatures of Lexmark employees after assembly and functional testing.
IBM Model M Space Saver (without numeric keypad ) of the page to see the clearly curved, ergonomically designed keyboard area of all the model M.
IBM Model M Space Saver Interior view, back: the steel plate in the center and the scan code above board. Also see the 50 Plastiknietköpfe connecting distributed on the steel plate, keyboard keys foils and housing.
IBM Model M industrial version in gray. " Space Saver " version without numeric keypad with 84 keys.
Unicomp " Customizer " version of the IBM Model M keyboards.
Closeup view of a current black colored Unicomp "Space Saver" Model M keyboard.
A to a Dvorak layout vice infected Model -M, easily performed by the removable keycaps.