One of the most iconic lineages of IBM keyboards was the Converged Keyboard (aka, ’24 function key keyboard’). These large keyboards with their characteristic 24-key function key block have been in production continuously in one shape or form since 1983. Despite the affection many people hold for them, how the lineage developed was not widely understood and no real classification system existed for them. Unsaver? Battleship? Battlecruiser? Those are the main three terms we have typically come to use when differentiating these keyboards, but this ‘trinary’ way of describing ignores some glaring nuances. This two-part topic series aims to address this whilst also setting the record straight on how 1983’s 104-key Model F evolved into today’s Unicomp PC 122!

This is part two of the ASK Converged Keyboard Classifications series, covering Model M family (Model 1A) versions of these keyboards and detailing my five-type classification system for them.

Note

The ‘types’ described are not a replacement or alternative to the Model M ‘generations’ some may refer to. Those generations describe production quality differences such as the keyboard assembly’s backplate thickness, whereas these types describe feature compliments irrespective of production quality changes. Most types were made across multiple generations. For each type, this span is explained.

Additionally, this page doesn’t compare/focus on the functional layouts on the keyboards (for example, typewriter versus data entry, 3270 versus 5250, etc.) beyond what’s needed to differentiate types. Please see the Differentiating IBM 3101, 3270 & 5250 terminal keyboards topic for such commentary.

Contents

Prelude

More information: Comparison & classifications of 104-key & 122-key Model F Converged Keyboards (coming Q3 2024)

122-key Model F top (3180-2)[ASK]
122-key Model F top (3180-2)[ASK]

All 122-key Model Ms can trace their origins to the 122-key Model F. The so-called “F122” itself evolved from the slightly earlier 104-key and 127-key Model Fs and stylistically served as the base for the “M122’s” design. The 122-key Model F was first released as the IBM 3270 Personal Computer’s 5271 Converged Keyboard, which was announced in October 1983 and available from Q1 1984[2][2]
IBM – IBM 3270 Personal Computer Brief Description of Announcement, Charges, and Availability (#186-117) [accessed 2023-01-23].. “F122” and the Type 1 “M122” described in the next section are virtually identical from the top, so the only sure way to tell them apart (if the part number isn’t already known, the person testing is unsure of the feel and sound difference between a Model F’s capacitive buckling springs and a Model M’s membrane buckling springs (or there’s no access to the keyboard, period), and the keyboard is unmodified) is the bottom cover set piece:

  • If the bottom is painted black and made of metal, it’s a Model F.
  • If the bottom is pearl white and made of plastic, it’s a Model M.

Images

Type 1 bottom (3179-1)[ASK]
Type 1 profile (3179-1)[ASK]
Type 1 foot (3179-1)[ASK]
Type 1 plug (3179-1)[ASK]
Type 1 DIPs (3179-1)[ASK]

Description

Perhaps the most conservatively designed Model M conceived, the Type 1 “M122” looks virtually identical to the 122-key Model F from the top and sides. Type 1s even largely retain the stepped keycaps where a PC keyboard’s modifier keys would reside, a feature most people more associate with Model Fs than Model Ms (though there are exceptions[5][5]
ASK Keyboard Archive – P/N 1386887 (1986, IBM-US) [accessed 2023-10-10]. License/note: photos saved from volatile eBay listing, used under fair dealing.). The surest way to tell a 122-key Model F and a Type 1 122-key Model M apart would be to look on the bottom and see if the keyboard has a black painted metallic bottom cover (Model F) or a pearl-coloured plastic bottom cover (Model M). An IBM silver-square badge is present on the right-hand side of the 24-key bank’s raised platform. Depending on the family the keyboard’s host terminal belongs to, those 24 keys could have a “PFxx” (3270-style) or “Cmdxx” (5250-style) nomenclature. Some regional variants may have language-specific nomenclatures as well; for example, Spanish keyboards could have “FPxx” (3270) or “Mdtxx” (5250) nomenclature instead. The Type 1 has a permanently attached coiled cable with a 240-degree 5-pin DIN plug. The plug has a screwable metal jacket and is straight unlike the Type 1’s immediate successor. All known Type 1s use IBM scancode set 3 for communication. Some IBM 3270 family keyboards may have an 8-position DIP switch bank on the bottom for possible keyboard ID settings (which can be ignored when using a modern terminal-to-PC keyboard converter). Notably amongst “M122s”, the Type 1 retains the side-accessible two-setting riser feet from the “F122”.

Basic specs

Generations

Being the earliest “M122s”, Type 1 was mostly produced to first-generation buckling spring Model M specifications. This principally means their backplates are usually amongst the thickest for Model Ms and they have a ‘rainbow’ effect thanks to heat-treated/chromated steel. Despite the later types (notably Type 3) becoming more prominent by the ’90s, keyboards based on the Type 1 design were produced as late as 2000 by Unicomp[7][7]
Brandon @ ClickyKeyboards – 2000 IBM model M122 battleship (1389262) Feb 22 2000 with original box [accessed 2023-09-18].. Type 1s produced beyond 1986 could sport generational characteristics of later Model Ms such as having grey and thinner backplates and (from ~1992 onwards) four drainage holes on the bottom cover (branding didn’t change though).

Known host computers & terminals

Images

Type 2 bottom (3197)[ASK]
Type 2 profile (3197)[ASK]
Type 2 DIPs blanking plate (3197)[ASK]

Description

Generally, the Type 2 “M122” retains the overall design language of the 122-key Model Fs like Type 1 but a few more changes have been made to further differentiate the designs. Type 2 crucially lacks the side-accessible two-setting riser feet of both previous designs, so a Type 2 can be distinguished from a Type 1 via the lack of grey buttons on either side and from a “F122” via the aforementioned and the fact 122-key Model Ms’ use of pearl plastic bottom covers. Instead of riser-style feet, the Type 2 has single-setting flip-out feet similar to other Model Ms (though longer). Beyond that, much is the same, such as Type 2’s use of an IBM silver-square badge on the right-hand side of the 24-key bank’s raised platform. Those 24 keys could also have a “PFxx” (3270-style) or “Cmdxx” (5250-style) nomenclature depending on the host terminal’s family. Some regional variants may have language-specific nomenclatures as well; for example, Spanish keyboards could have “FPxx” (3270) or “Mdtxx” (5250) nomenclature instead. Type 2 has a permanently attached coiled cable with a 240-degree 5-pin DIN plug, but instead of having a straight screwable metal jacket, the Type 2’s DIN plug’s jacket is plastic and the connector is at a right angle. All known Type 2s use IBM scancode set 3 for communication. Whilst 3270-style Type 2 “M122s” could also have an 8-pin DIP switch bank for keyboard ID purposes (and if present, it can be ignored when using a modern terminal to PC keyboard converter), the recess for it is at a different location and it seems less likely to be used and thus blanked off. Whilst some Type 2s have stepped keycaps where a PC keyboard’s modifier keys would reside[13][13]
ASK Keyboard Archive – P/N 0985954 (1986, IBM-NL) [accessed 2023-08-09]. License/note: photos saved from volatile Donan??mHaber auction ad listing, used under fair dealing., the practice once again seems less common than for Type 1.

Basic specs

Generations

Whilst Type 2s weren’t made as early as Type 1, the earliest Type 2s would have been produced to first-generation buckling spring Model M specifications as well. This likewise means their backplates can be thicker than later Model Ms and have a ‘rainbow’ effect thanks to heat-treated/chromated steel. However, Type 2s were the main 122-key Model M design for the rest of the 1980s, so many were also produced to second-generation specs with slightly thinner grey backplates instead (though “M122s” in general didn’t follow IBM Enhanced Keyboard per-generating branding, so all Type 2s retained the IBM silver-square badge). Type 2s were manufactured as late as 1996[15][15]
Brandon @ ClickyKeyboards – 1996 IBM model M122 battleship (1390572) 2/17/96 with original styrofoam [accessed 2023-09-18]., however, those indeed sport generational characteristics of later Model Ms such as the aforementioned backplate changes and (from ~1992 onwards) received four drainage holes on the bottom cover (branding didn’t change though).

Known host computers & terminals

Images

Type 3 top (IBM twinax (early))[ASK]
Type 3 bottom (IBM twinax (early))[ASK]
Type 3 profile (IBM twinax)[ASK]
Type 3 foot (IBM twinax)[ASK]
Type 3 jack (IBM twinax)[ASK]

Description

The Type 3 “M122” represented a radical departure from previous IBM Converged Keyboards. Whilst both previous types were stylistically more “Model F” than Model M and could be seen as mere internal reworks of the 122-key Model F, Type 3 looks more like a Model M-based keyboard. Type 3 features the distinct Model M wedge shape profile, slimmer bezels between the keys and the side edges, a smaller surface area around the 24-key bank’s raised platform, and a three-way cable router on the bottom cover. Type 3 also does away with the IBM square badge and instead has an IBM oval badge – originally with black text, later with blue text – on the lefthand side of the keyboard. Very late Unicomp examples made for IBM abandoned the oval badge and instead printed “IBM” text on the top-right cover. Regardless of the keyboard having a 3270 or 5250 style functional layout, the 24-key bank exclusively has “Fxx” nomenclature instead of “PFxx” or “Cmdxx”. Type 3 has a permanently attached coiled cable but its coils are smaller and the cable is thinner than previous types (more suited to fit the aforementioned cable router), and the DIN plug is replaced with a modular 8P5C jack (the same physical jack used for ethernet/RJ-45). Despite this, Type 3s continued using IBM scancode set 3 for communication so only a physical change to connectivity was made. Type 3 abandoned support for DIP switches, so not even a recess and blanking plate are present for them. Due to shared design and moulds, some Type 3s may have a visible area where lock-light LEDs would be present for Type 4 (though some lack this altogether).

Basic specs

Known host computers & terminals

Type IV

The Type 4 122-key Model M was technically a variant of the Type 3 Model M Converged Keyboard, though now referred to as a “[PS/2] Host Connected Keyboard”. Instead of being designed for specific terminals, the IBM (and Lexmark) PS/2 Host Connected Keyboard carried the “battlecruiser” 122-key design towards PCs running terminal emulation software. They entered production around 1990.

Images

Type 4 top (IBM-brand)[ASK]
Type 4 lock-light overlay[ASK]

Description

The Type 4 “M122” is esse