Editing IBM 122-key terminal keyboards (section)

==Types==
Like the Enhanced Keyboard, the M122 went through many design changes during its life. The case, keycaps, controllers, membrane layouts, lock lights (or lack thereof), and other small details all changed at some point. There are no designations of the differences in M122s in any official IBM, Lexmark, or Unicomp literature, so the "Type" classification was invented by enthusiasts to keep track of the major changes. It should be noted that "Types" are not the same as "Generations" - for example, some types were produced long enough to have different backplate thicknesses despite the outward appearance not changing<ref name="shark122typecomp" />, unlike Enhanced Keyboards. The types are in approximately chronological order.

===Type I===
The first type of M122, the Type 1, is the earliest observed. It strongly resembles the IBM Model F 122 keyboard. From the top and sides, a Type I M122 is indistinguishable from an F122. It shares the F122’s top case, large 2-level flip-down feet, and square metal badge. The top case of the F122 is made of more brittle, painted plastic, and the M122’s case is made of the same plastic used in the Enhanced Keyboard. However, it is impossible to accurately distinguish between the two from photos. The biggest external difference is the bottom case. An F122 has a black stamped-metal bottom case with a separate plastic piece on the back, while the Type I M122 has a one-piece beige plastic bottom case. There is a blanking plate on the bottom case to which dip switches are sometimes fitted.

The top case of a Type I M122, with a little modification to the inside, can be fitted to replace the top case of an F122. Many F122 owners do this because the Type I M122’s case is made of a much more durable plastic.

The Type I M122 is generally the earliest version of M122, but some examples were produced by Lexmark in the 1990s. These Lexmark-produced examples have a unique bottom case with cutouts for drainage channels not seen on early IBM-produced Type I M122s.

Type I M122s usually have the thick, rainbow-colored backplate also found on early Enhanced Keyboards. Type I M122s also feature fixed, coiled cables with 240 degree 5-pin DIN connectors.

<gallery widths=250 heights=147>
File:IBM_1389262_31MAR94.jpg|Type I M122, P/N 1389262, made by Lexmark in 1994.
File:IBM_1389262_31MAR94_back.jpg|Back view, showing large flip-down feet
</gallery>

===Type II===
The second type, the Type II, represents a cost-saving simplification of the Type I. The overall shape of the case is the same, but the F122-style flip-down feet are replaced with small Enhanced-Keyboard style feet integrated into the bottom case. Virtually everything else about the keyboard remained the same.
Type II M122s generally feature fixed, coiled cables with right-angle 240 degree 5-pin DIN connectors.

One of the most common Type II M122 part numbers was 1390702, a typewriter keyboard associated with the 3192 Display Station.<ref name="3192announcement" />

<gallery widths=250 heights=147>
File:IBM_1390702_08AUG89.jpg|Type II M122, P/N 1390702, made by IBM in 1989.
File:IBM_1390702_08AUG89_back.jpg| Back view, showing the small flip-down feet.
</gallery>


===Type III===
The third type, the Type III, included a major redesign of the case. The new case for the Type III M122 was strongly influenced by the Enhanced Keyboard, with sharp corners, small bezels, and an oval-shaped grey or blue plastic IBM badge. The bottom case has a slot running across the back allowing the user to route the cable closer to the left or ride side. Most Type III M122s have thinner, fixed, coiled cables with RJ45 connectors. Some Type III M122s have blanking plates for a lock light sticker, similar to terminal versions of the Enhanced Keyboard.


Many Type III M122s came with with IBM's Infowindow line of terminals.<ref name="3477announcement" />

<gallery widths=250 heights=147>
File:IBM_1394308_03OCT89.jpg|Type III IBM M122, P/N 1394308, made by IBM in 1989.
File:IBM_1394308_03OCT89_back.jpg|Type III IBM M122, P/N 1394308, back view.
</gallery>

===Type IV===
The fourth type, the Type IV, has several minor changes from the Type III. Type IV M122s generally have PS/2 connectors, and they feature lock lights similar to the Enhanced Keyboard. Unicomp manufactures the Type IV M122 to this day.

Some Type IV M122s have rectangular Lexmark logos or the corresponding blanking plate, similar to Lexmark produced Enhanced Keyboards and Unicomp Classic 101s. Type IV M122s were manufactured with many different badges besides IBM, Lexmark, and Unicomp, including [https://deskthority.net/viewtopic.php?f=62&t=13518&p=300401&hilit=lynk#p300401 Lynk], [https://deskthority.net/wiki/File:UNICOMP_LYNX_301-5522-01.jpg Lynx Technologies], [https://deskthority.net/wiki/File:Decision_Data_Terminal.jpg Decision Data], [https://deskthority.net/wiki/File:ComputerLab_International_M122.jpg ComputerLab International], and [https://www.affirmative.net/CustomPages/Home.aspx Affirmative Computer Products].

<gallery widths=250 heights=147>
File:AFFIRMATIVE_AC40956.jpeg| A Unicomp Made, Affirmative branded M122.
File:AFFIRMATIVE_AC40956_back.jpeg|Back view.
</gallery>