Comparison & classifications of 122-key Model M Converged Keyboards

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.

Contents

Prelude

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

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:

Type I

The Type 1 122-key Model M was the first Model M (membrane buckling spring bearing) take on the IBM Converged Keyboard, continuing the "battleship" lineage started by the 127-key Model F. The "M122" first appeared as the "membrane type (new type)" keyboard unit for the IBM 3205 Color Display Console by September 1985, contrasting the "capacitance type (old type)" keyboard (122-key Model F)^[4][4]
IBM - IBM 3205 Color Display Console Maintenance Information (#SY18-2121-1) [accessed 2023-10-10]. License/note: document archived by bitsavers..

Images

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

Part numbers

53 part numbers have been found in the ASK Keyboard Part Number Database. If you believe a relevant part number is missing, you can help improve this list by requesting a submission for it to be added.

Directory entries

2 keyboards have been found in the ASK Keyboard Directory.

Type II

The Type 2 122-key Model M was the second iteration of the Model M Converged Keyboard line introduced less than a year after Type 1, slightly simplifying the overall design but maintaining a similar vibe. It first appeared in June 1986 for the IBM 3191 (3270-family) and 3196 (5250-family) Display Stations^[11][11]
IBM - IBM 3191 Display Station Brief Description of Announcement, Charges, and Availability (#186-117) [accessed 2023-01-23].^[12][12]
IBM - IBM 3196 Display Station Brief Description of Announcement, Charges, and Availability (#186-111) [accessed 2023-01-23]..

Images

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 DonanımHaber 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

Part numbers

22 part numbers have been found in the ASK Keyboard Part Number Database. If you believe a relevant part number is missing, you can help improve this list by requesting a submission for it to be added.

Directory entries

1 keyboard has been found in the ASK Keyboard Directory.

Type III

The Type 3 122-key Model M was a major rework of the Model M Converged Keyboard. It marked the end of the Model F-style "battleship" lineage dominance and replaced it with a slimmer and more Model M-feeling "battlecruiser" design. It was introduced exclusively for the IBM InfoWindow family of terminals, which began with the InfoWindows 3471 (3270-family) and 3476 (5250-family) in June 1989^[20][20]
IBM - IBM InfoWindow 3471 Display Station Brief Description of Announcement, Charges, and Availability (#189-096) [accessed 2023-01-23].^[21][21]
IBM - IBM InfoWindow 3476 Display Station Brief Description of Announcement, Charges, and Availability (#189-097) [accessed 2023-01-23]..

Images

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

Quiet Touch variant

For IBM InfoWindow II 3488 Modular Display Station models V11, V13, V41, V43, V51 and V53^[24][24]
IBM PC Partner Info - InfoWindow II 3488 Display Terminal - Product Overview (#VLAR-3QFN8U) [accessed 2023-09-29]. License/note: accessed via kev009's archive., a version of the Type 3 122-key Model M with Quiet Touch rubber dome key-switches was available^[25][25]
Kent Lâm @ YouTube - IBM Model M Bolt-Modded vs. Stock | Buckling Spring Sound Compare [accessed 2023-09-29]. License/note: timestamped to 2:05.. "Quiet Touch" was IBM's, Lexmark's and Unicomp's term for a quieter (compared to buckling spring) key-switch design. This keyboard was P/N 92G9006 (FRU 92G9007) and formally called the IBM 122-key Quiet Typewriter Keyboard. Whilst Unicomp would later make Type 3-based "M122" designs that used Quiet Touch key-switches, this part number is the only confirmed example of an IBM-brand and/or Lexmark-made Quiet Touch 122-key Converged Keyboard of any type.

Generations

Being introduced in 1989, Type 3 was originally produced to second-generation buckling spring Model M specifications. The expansion of the InfoWindow family into the mid-'90s kept Type 3 in widescale production for many years, so third and fourth-generation Type 3s are also common (Type 1 and II were also produced during this time, but it seems they weren't produced to the same scale Type 3 was in the '90s so they're more common in their original generations). Type 3 generations followed the Enhanced Keyboard's, so the original black-text IBM oval was replaced with a blue-text one and four drainage holes were added to the bottom cover around 1992. Type 3 was ultimately produced by IBM itself until the end of 1999^[26][26]
ASK Keyboard Archive - P/N 1394317 (1999, IBM-UK) [accessed 2022-10-06]. License/note: archived from volatile eBay listing and used under fair dealing., but Unicomp produced Type 3s for IBM until at least 2004^[27][27]
ASK Keyboard Archive - P/N 1394124 (2004, Unicomp) [accessed 2023-04-10]. License/note: photos saved from volatile eBay listing. and has made them for other companies.

Known host computers & terminals

Part numbers

35 part numbers have been found in the ASK Keyboard Part Number Database. If you believe a relevant part number is missing, you can help improve this list by requesting a submission for it to be added.

Directory entries

3 keyboards have been found in the ASK Keyboard Directory.

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

Description

The Type 4 "M122" is essentially a specialised version of Type 3 that has PC compatibility, so it's considered a terminal emulator keyboard rather than simply a terminal keyboard that most of its predecessors were. The best way to tell IBM-branded Type 3s and 4s apart is the latter's presence of lock-light LEDs in the top-right corner of the keyboard. Type 4s were both expected to act as standard PC keyboards and terminal keyboards by their very nature, so to reflect this, they also have at least two-colour dye-sublimated legends to differentiate PC-only functions (usually in blue) and terminal/universal functions (in black). IBM and Lexmark branded Type 4s seem to be orientated for IBM 3270 terminal emulation. Type 4s also ditched attached cables in favour of a removable SDL-based cable that IBM Enhanced and Space Saving Keyboards famously used. Being a PS/2 keyboard, Type 4s used grey coiled cables terminating in a 6-pin Mini-DIN PS/2 plug, but they should also be compatible with SDL cables that use AT-style (180-degree) DIN plugs as well. Beyond that, the rest of the Type 4 design is the same as Type 3's. Type 4 features the distinct Model M wedge shape profile, slimmer bezels between the keys and the side edges, the smaller surface area around the 24-key bank's raised platform, and retains the three-way cable router (even though many Type 4 cables won't fit it). IBM-branded Type 4s made by IBM themselves or Lexmark also used IBM oval badges with (originally) black text inside and then later blue text, but all Lexmark-branded Type 4s used a simple rectangular Lexmark logo. The IBM-branded Type 4's 24-key bank exclusively has "Fxx" nomenclature instead of "PFxx" or "Cmdxx". Lexmark-branded Type 4s could have "PFxx" nomenclature. Type 4s used IBM scancode set 2 (though they could likely change to set 3 via mode selection). Type 4s also don't have DIP switch banks or even a place for them in their moulds.

BOS-branded variant

Whilst the Unicomp era for Type 4s described in the Unicomp's Type III & IV section is associated with third-party rebranding, this practise actually began at least by the Lexmark era. Better On-Line Solutions (BOS) branded a Host Connected Keyboard (such as P/N 1369969) made by Lexmark that was physically the same as a Lexmark-branded Type 4 down to the rectangular branding (just with "BOS" branding instead of "Lexmark"). Functionally though, the BOS Type 4 is a rare example during the pre-Unicomp days of a Type 4 with IBM 5250 terminal legends instead of 3270.

Generations

The earliest production year for Type 4 was 1990, so they arrived slightly later than Type 3 but not late enough to have a significant impact on their generational characteristics. They were also originally produced to second-generation buckling spring Model M specifications though they adapted to new generations as they came. In line with Enhanced Keyboard generational changes, IBM-branded Type 4's oval badges that originally had black text were updated to have blue text sometime around 1992. Regardless of branding, the Type 4's bottom cover received four drainage holes around this time as well. IBM's production of Type 4 came to an end at the same time as their Type 3 production (end of 1999), but Unicomp continues producing Type 4s for themselves and other companies to this day.

Known host computers & terminals

The Type 4 (as the IBM PS/2 Host Connected Keyboard) was available through IBM's Select-A-Keyboard (sometimes written as "Selecta Keyboard") scheme when purchasing an IBM Personal System/2 computer. The scheme allowed customers to choose from a variety of keyboards for their system at the time of purchase for no additional charge, this included the IBM-branded Type 4 "M122" as well as keyboards such as the IBM Enhanced Keyboard and Space Saving Keyboard^[36][36]
IBM - IBM Personal Systems Technical Solutions Issue 4, 1991 (#G325-5013-00) [accessed 2023-10-10]. License/note: document archived by Ardent Tool.. It's presently unclear if Lexmark-branded Type 4s were shipped with any specific systems.

Part numbers

50 part numbers have been found in the ASK Keyboard Part Number Database. If you believe a relevant part number is missing, you can help improve this list by requesting a submission for it to be added.

Directory entries

7 keyboards have been found in the ASK Keyboard Directory.

Unicomp's Type III & IV

Unicomp, the current torchbearers of the Model M keyboard family, have produced 122-key keyboards since their founding and continue to do so today. Unicomp can produce keyboards that could be considered Type 3, 4 or 5 122-key Model Ms with significant customisation for individuals and companies, hence this section is dedicated to such keyboards (Types 3 and 4) beyond IBM branding. Due to the divergence of these designs today from their origins, some have considered Unicomp-made non-IBM-brand Type 3 and 4 keyboards to be their own subtype (hence "Type 3.5" and "Type 4.5" respectively have emerged to limited adoption).

Unicomp produces their 122-key keyboards in four distinct versions that they use as marketing names:

In addition, Unicomp has produced 122-key keyboards with either clicky buckling spring or Quiet Touch brand rubber dome key-switches.

"Type 3.5" images

"Type 4.5" images

Differences to vintage Types III & IV

Both types

Unicomp-made Type 3 122-key keyboards are produced based on the last generation introduced during the IBM/Lexmark era - the fourth generation. So overall design language and features aren't different to those, but there are some considerations:

Type III only

The Unicomp Terminal 122 keyboard is the direct successor to the IBM InfoWindow 122-key Typewriter Keyboard, thus Unicomp can still make them with modular 8P5C jacks so they can fit old IBM InfoWindow terminals. Despite that, Unicomp can also make their Type 3s with AT-style DIN or PS/2 Mini-DIN connectors for third-party terminals.

Type IV only

The Unicomp Emulator 122 keyboard is the direct successor to IBM and Lexmark PS/2 Host Connected Keyboards. As such, they also have at least two-colour dye-sublimated legends to differentiate PC-only functions (usually in blue) and terminal/universal functions (in black) as vintage Type 4s would have. Many also have lock-light LEDs in the top-right corner, though companies Unicomp worked with seemed to have the option to cover the entire area in a solid overlay if desired. Over the years, Unicomp and third-party-brand Emulator 122 keyboards could use several types of cables/connectors including SDL to PS/2, attached PS/2 and attached AT-style DIN. Unicomp PC 122 keyboards take the evolution slightly further. They also have more modern PC-centric legends and are also available with either PS/2 or USB connectivity. One caveat with the PC 122's default keymap consumers have observed is that the F13 to F24 key row is programmed to be 'shifted' F1 to F12 keys by default. For affected keyboards, the Dealing with Unicomp PC 122's shifted F13-F24 keys row guide can be referred to for possible options to mitigate this. Additionally, in June 2023, Unicomp introduced a new USB controller card using the reflashable Raspberry Pi Pico that opens new opportunities for reprogrammability.

Third-party brands

The following companies (other than Unicomp itself or IBM) have put their brand on a Unicomp-made 122-key keyboard of either Type 3 or 4 designs:

Ordering

As of October 2023, Unicomp only advertises the 5250-style PC 122 consumer-grade keyboard as a USB or PS/2 keyboard on their storefront. If one desires an IBM-compatible keyboard or a PC 122 with 3270-style legends and/or different languages, Unicomp's Keyboard Configuration Tool can be used to order them. For an IBM-compatible Type 3 122-key Model M, the following options should produce such a keyboard:

For an IBM-compatible Type 4 122-key Model M, the following options should produce such a keyboard:

It's recommended that a prospective buyer email Unicomp to inquire about a specific custom keyboard specification before ordering. Also note Unicomp doesn't use this type system, so below are some alternative names you can use in correspondence/requests:

Type V

The Type 5 122-key Model M was a minor enhancement to the Unicomp-era Type 4 122-key Model M intended for retail scenarios. Whilst Unicomp later produced Enhanced Keyboard style versions under the same name umbrella, Type 5s were referred to as Unicomp Point Of Sale Keyboards or Unicomp MSR 122. Their earliest appearance on Unicomp's website was in December 1998^[44][44]
Unicomp - Unicomp's Terminal Keyboards [accessed 2023-10-08]. License/note: retrieved via Wayback Machine (1998-12-03 capture).. Whilst they seem to be the rarest type, they're technically still orderable from Unicomp.

Images

Description

The Type 5 "M122" is ultimately within the same lineage introduced by Type 3 in 1989, so many design details were carried forward and are shared with Unicomp's Type 3s and 4s. But what made Type 5 "M122" unique was primarily the inclusion of an attached magnetic stripe reader (MSR) for reading credit and debit card data and the fact it seems customers had a lot of customisation options to choose from. For example, Unicomp stated that their POS keyboards could have a built-in RS-232D port for attaching external barcode readers^[44][44]
Unicomp - Unicomp's Terminal Keyboards [accessed 2023-10-08]. License/note: retrieved via Wayback Machine (1998-12-03 capture). and/or even an integrated pointing device^[46][46]
Unicomp - Product Catalog (2000) [accessed 2023-10-08]. License/note: used under fair dealing., meaning Type 5s are candidates for the only official 122-key Model Ms with TrackPoint-like pointing sticks or integrated trackball modules. Type 5s were technically available with a range of PC, terminal and terminal emulator layouts, meaning the keycap legends could be significantly varied. PC and terminal-only keyboards would have all-black legends on their keycaps, whereas terminal emulator keyboards would have the [at least] two-colour legends to differentiate PC-only functions (usually in blue) and terminal/universal functions (in black) that Type 4s are notable for. 3270 and 5250 style legends were also available. Ultimately, all these physical and functional options mean what relatively little Type 5s exist are likely to be highly unique to each other. Type 5 "M122s" could have attached cables terminating in either a 5-pin AT-style (180-degree) DIN or a 6-pin Mini-DIN PS/2 plug. Despite the MSR attachment, only one cable is needed since the MSR module itself acts as a passthrough. Type 5s retained the distinct Model M wedge shape profile, slim bezels between the keys and the side edges, smaller surface area around the 24-key bank's raised platform, and the three-way cable router (though many Type 5 cables won't fit it). No IBM-branded Type 5s have been discovered, so the only branding observed is a logo (Unicomp's or a third party's) across the lock-light LED overlay. Regardless of the keyboard having a PC, 3270, 5250 or combination functional layout, the 24-key bank seems to have exclusively used "Fxx" nomenclature. Type 5s used IBM scancode set 2. As with Types 3 and 4, Type 5 "M122s" never had DIP switches.

Basic specs

Generations

There haven't been any attempts to categorise Unicomp keyboard production over the years, thus they're all presently considered to be within a continuation of the fourth generation despite the case material changing from PVC to PC+ABS at some point. Being birthed into the fourth generation means they had relatively thin backplates and four drainage holes on the bottom cover from the start. Perhaps one thing to note is that early Unicomp keyboards generally used coiled cables, but by the end of the 2000s, they had phased into using straightened cables.

Ordering

As of October 2023, Type 5 can be ordered from Unicomp's Keyboard Configuration Tool. The following options should produce such a keyboard:

It's recommended that a prospective buyer email Unicomp to inquire about a specific custom keyboard specification before ordering. Also note that Unicomp doesn't use this type system, so a Type 5 keyboard can alternatively be referred to as a "122-key point of sale keyboard" or "MSR 122 keyboard" in such a request.

Part numbers

1 part number has been found in the ASK Keyboard Part Number Database. If you believe a relevant part number is missing, you can help improve this list by requesting a submission for it to be added.

Directory entries

No examples of this keyboard are presently recorded in the Keyboard Directory.

Exceptions

Whilst for the most part the types described above are consistent and unique from each other, there have been times when the lines between types have been blurred or a keyboard has been assembled and/or modified with components from multiple types. Below are examples of such keyboards and statements from the author on how they're categorised.

Type I-style host-connected keyboard

In the late '80s, a unique variant of the Type 1 122-key Model M was in production that seems to be a predecessor to the Type 4-based IBM PS/2 Host Connected Keyboard. P/N 1393656 has most of the physical traits of Type 1 but has a cable terminating in a PS/2 (6-pin Mini-DIN) connector and is intended to be PC compatible. In what limited IBM literature is available that references this part number, it was an IBM PC3270 keyboard and was explicitly stated to be the "old version" to P/N 1397000^[48][48]
IBM - IBM Tivoli System Automation for Integrated Operations Management User's Guide (#SC23-6113-01) [accessed 2023-10-10]. License/note: document archived by usermanual.wiki. (a Type 4 122-key Model M). Note that this keyboard is distinct from the Model M versions of the IBM 5271/5273 (3270 Personal Computer series) Converged Keyboards such as P/N 1389098, which despite also having emulator-style blue legends are still electrically terminal keyboards. It's believed that this was a short-term solution for a PS/2-compatible host-connected keyboard before the official Type 4-based PS/2 Host Connected Keyboard was available.

In the ASK Keyboard Part Number Database, this keyboard is simply considered [to be a specialised variant of] Type 1 unless any further information about P/N 1393656 is discovered that sets it even further apart.

Unicomp-sold Type I/Type II hybrid keyboards

Around the turn of the millennium, Unicomp sold IBM-branded 122-key Model Ms that had both Type 1 and Type 2 characteristics. For example, ClickyKeyboards once had a P/N 1390416 (a Spanish-language 3270-style typewriter) keyboard that had a cover set from a Type 1 122-key Model M (with dual-setting riser feet) but has a cable that was previously exclusive to Type 2 122-key Model Ms (plastic-jacketed and right-angled DIN plug)^[49][49]
Brandon @ ClickyKeyboards - 2000 IBM model M122 battleship (1390416) MAR 09 2000 with original box [accessed 2023-09-17].. In such cases, it's believed Unicomp assembled older-style keyboards with a limited selection of pre-made components left over from IBM and Lexmark.

In the ASK Keyboard Part Number Database, any such keyboards will be documented as the type they were originally intended to be when in production by IBM and/or Lexmark. Hybrid types are believed to be a very small exception to the full production of an affected part number.

Summary

Further reading & resources

Internal

Sources

ASK. Admiral Shark's Keyboards original content. License/note: CC BY-NC-SA 4.0.

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