After the “scheduled” end of my Unicomp Model M, a keyboard that ended up as electronic scrap shortly after the warranty expired due to electronic damage to the controller, total internal gluing and unavailable spare parts, I looked for a more robust, sustainable alternative. Unfortunately, repairing the Model M proved to be uneconomical due to its lack of modular construction and proprietary technology, which was doubly disappointing given its classic design. So I turned my attention to a model from the real engineering era: the IBM Model F122.
I opted for one of the elaborately reproduced versions from Model F Labs and invested a total of around 530 euros, including shipping and customs duties (90 euros including import VAT and DHL). What followed was a wait of several months, almost symbolic of the patient return to an era when you had to be prepared to wait longer for quality. As a long-time user of mechanical keyboards and someone who has been involved with input devices from an enthusiast’s perspective for years, it was only a matter of time before I approached the IBM Model F122. as one of the forefathers (or is it better to say foremothers?) of mechanical keyboards. Fascinated by its history, its technology and the legendary typing feel, I decided to buy one of the modern reproductions, with considerable expectations. And yes, in the end with a certain amount of disillusionment. But I’ll come to that in a moment, because I want to remain objective.
Development history of both keyboard generations
The history of IBM keyboards is closely linked to the development of buckling spring technology. Originally developed as a mechanical principle for triggering signals, the buckling spring was first used in series production by IBM in the early 1980s in the Model F series. This is a spring mechanism in which the steel spring buckles under pressure and triggers a capacitive signal via a hammer mechanism. This technology enabled a very precise query with high mechanical durability, but also with a distinctly loud acoustic feedback. The Model F122 was designed as a terminal keyboard for professional environments where volume was not a primary concern. It was part of a larger peripheral ecosystem for the IBM 3270 terminal series and set new standards for industrial use with its solid steel housing, capacitive matrix and robust mechanics. Of course, I was aware of all this when I embarked on the Model F adventure.
With the introduction of the Model M in the mid-1980s, IBM made a strategic turnaround: Buckling-Spring technology was retained, but combined with membrane-based evaluation. This allowed a significant reduction in costs, simpler production and more compact designs. The Model M quickly became the office standard – particularly because it retained the typical typing feel, but was quieter overall and more comfortable for continuous use at writing stations. The volume decreased and the acoustic feedback became softer and more muted, partly due to the modified geometry of the hammer and damping zones.
The difference in volume between the two series is still clear today: while the Model F with its bright, metallic click is reminiscent of a miniature relay and makes every keystroke clearly audible in the room, the Model M remains comparatively civilized. In modern working environments, this is a factor that should not be underestimated, as the Model F can certainly be perceived as annoying if you are not operating it alone or specifically appreciate acoustic feedback. For many enthusiasts, this is precisely the appeal, but the Model M is often more practical for everyday use.
The special features of the F122 controller
The keyboard is based on a modern RP2040 microcontroller, which provides a powerful and future-proof platform. Thanks to full compatibility with QMK and VIAL, almost all keyboard functions can be flexibly adapted – from macros to complex layout definitions. The design of the board respects the original mounting and connection structures of the historic Model F and Beam Spring keyboards, allowing it to be integrated without major modifications. In addition, it offers support for solenoid drivers, with which the classic mechanical “click” feedback of the IBM terminals can be reproduced. Optional PS/2 compatibility is also possible via a supplementary daughterboard, which means that even older systems continue to be supported.
The “Leyden Jar” controller is a modern, open-source replacement board for IBM Model F and Beam Spring keyboards. It was designed by a developer with the pseudonym “Rico”, not “rpiguy9907”. The project was initiated to offer an alternative to the existing Xwhatsit controller, especially in view of supply bottlenecks for microcontrollers. Development of the “Leyden Jar” controller began in April 2022. The first revision was successfully tested in various keyboard models, including the F77 model and Beam-Spring variants. The third revision brought improvements such as the elimination of external EEPROMs and the integration of additional columns for future keyboard models such as the F122. The “Leyden Jar” controller offers a modern and customizable solution for enthusiasts who want to equip their classic IBM keyboards with the latest technology.
Scope of delivery
The scope of delivery included the keyboard itself, loose keycaps, a USB cable and some documentation. There were no accessories for height adjustment, as the Model F traditionally does not have stands, as it was designed for inclined installation positions. The cabinet had minor paint imperfections and fraying of the cast elements, which are difficult to convey for a reproduction at a final price of over 530 euros (including shipping and import duties). Karsten (thanks for the assembly) also had to remove several keys and readjust the springs underneath, as individual keys were hanging or bouncing. There is a “construction diary” on this in the next chapter
Technical data of the Model F122 (reproduction)
| Characteristic | Specification |
|---|---|
| Layout | 122 keys (122-key terminal layout, ANSI variant) |
| Key spacing | 19.05 mm (standard key spacing) |
| Key technology | Buckling spring with capacitive scanning |
| Controller | RP2040 (Leyden Jar), QMK and VIAL compatible |
| Housing material | Steel, powder-coated (different variants available) |
| Keycaps | PBT, dye sublimation, IBM-compatible sculpted profile |
| Connection | USB-C (internal USB-A port on the daughterboard) |
| Compatibility | Windows, Linux, macOS (QMK/VIAL required) |
| Dimensions | approx. 49 × 21 × 5 cm (slightly variable depending on version) |
| Weight | approx. 3.7 kg |
| Origin | Developed in the USA, manufactured by a Chinese OEM |
| Scope of delivery | Keyboard, loose keycaps, USB cable, basic documentation |
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