Original specs/details

Full Name Unicomp 5250 Emulator for NLynx Technologies
Part NumberPart Number
The number used to describe this keyboard's specific release; usually specific for a target region, language or SKU, etc.
A designation from my own type naming scheme used to categorise this keyboard with or from others by their common features and market intent but may/may not be derived from official names.
Model M Type IV 122-key Host Connected Converged Keyboard
A [keyboard enthusiast] community given name for this keyboard. It can be a shortening of its name and properties, a more abstract term, a real-life reference, or metonymy.
The name of the known switching mechanism that lies under this keyboard's keys.
IBM membrane buckling springs
Original KeycapsOriginal Keycaps
The keyboard's original keycaps' material and text/symbol printing technique.
PBT with dye-sublimated legends
The style of this keyboard's flip-out or extendable feet. If applicable, this may also state how many levels of height adjustment are available and whether the feet could be rubberised.
Single-setting elongated flip-out feet
The protocol(s) this keyboard can use to speak to the host computer (eg, scancode sets).
IBM Mode 2 (scancode set 2)
The keyboard-to-host connection. This is could be a description of a cable (its colour, whether its coiled, whether its detachable, and what connector is at its end) or the name of a wireless technology.
Black straightened-style fixed PS/2 mini-DIN cable
Form FactorForm Factor
The standardised or universally acknowledged name for this keyboard's layout form factor.
Production Date 2010-07-22
Acquisition Date 2023-03-31

About this keyboard type

Officially the IBM Personal System/2 Host Connected Keyboard, the Type 4 122-key Model M was a variant of the Type 3 Converged Keyboard intended for terminal emulation on IBM PS/2 personal computers. It wasn't designed with a specific PS/2 model in mind, instead, it was available as an option for any IBM PS/2 or later series model that qualified for IBM's Select-A-Keyboard scheme. Select-A-Keyboard allowed customers to choose from a variety of keyboards for their qualifying system at the time of purchase for no additional charge. Select-A-Keyboard and the PS/2 Host Connected Keyboard were both announced in June 1991 but production of these keyboards started at least a year earlier. Lexmark later produced its own self-branded version. Type 4 remains in production today as the Unicomp Emulator 122 (continuation of the professional host-connected keyboard) and PC 122 (a more consumer-orientated keyboard), produced under their own branding or for third-party thin client brands such as 10ZiG Technology, Affirmative Computer Products, BOS/BOScom, Development Concepts, Inc., I-O Corporation and NLynx Technologies.

Type 4 "M122s" are at their core just a specialised version of the Type 3 Converged Keyboard with PC compatibility, so it's considered a terminal emulator keyboard rather than simply a terminal keyboard that most of its predecessors were. The keyboard's design is for the most part identical and is still considered a "battlecruiser" or "battlecruiser-sized" keyboard by enthusiasts. But to reflect their nature as a dual-purpose keyboard, Type 4s also have at least two-colour dye-sublimated legends to differentiate PC-only functions (usually in blue) and terminal/universal functions (in black). Being a Converged Keyboard at their core, they have their recognisable top 24-key and lefthand side 10-key function key banks. The legends on the 24-key bank were generally "Fxx" nomenclature for 3270 or 5250-style keyboards. IBM and Lexmark branded variants were always intended for IBM 3270 emulation, but 5250-orientated versions are known for third-party branded Type 4s. All Type 4 "M122s" currently discovered use a typewriter-style layout with no data entry style version yet found.

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. Unicomp-made keyboards can have or lack these lights though, so in such cases, the two-colour legends on the keycaps can also be used to differentiate them. Like Type 3s, they have the distinct Model M wedge shape profile, (originally) oval-shaped IBM branding, slim bezels between the keys and the side edges, a small surface area around the 24-key bank's raised platform, and a three-way cable router on the bottom cover (though many Type 4 cables don't fit the longer channels). Type 4 "M122s" originally ditched attached cables in favour of removable SDL to PS/2 cables that IBM Enhanced and Space Saving Keyboards famously used. Unicomp later supplemented and replaced them with attached cables terminating in an AT-style DIN, PS/2 or Type-A USB plug. Type 4s were made of PVC during the IBM days, but Unicomp has since switched to using PC+ABS. Unicomp also introduced raven black-coloured versions of the Type 4, which today is now the standard option. Like Type 3, Type 4 "M122s" never had the DIP switches some of their predecessors could have. Quiet Touch rubber dome versions of Type 4 have been available since Unicomp took over production.