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Fujitsu (富士通, in full 富士通株式会社: Fujitsu Limited) is a Japanese manufacturer whose product range includes computer keyboards, industrial keypads and mechanical keyboard switches.

“Fujitsu” is short for “Fuji Tsushinki” (Fujitsu Limited was originally Fuji Tsushinki Manufacturing Corporation, an offshoot of Fuji Electric), while “Fuji” itself is short for Furukawa–Siemens, where the “ji” is derived from “Siemens”. That makes Fujitsu Siemens effectively Furukawa–Siemens Siemens!

A considerable amount of the information on Fujitsu keyboards and switches has been obtained through collaboration with Kiyoto in Japan, who has procured copies of many articles—mostly in Japanese—from the Fujitsu journal, which is accessible only from Japanese libraries. Fujitsu have given their permission for these articles to be republished here.


The term “FES” is common to the series names of all of Fujitsu’s keyboard switches. In 1970, the various FES types were illustrated in a photograph in the Fujitsu journal captioned “FES形押しボタンスイッチ外観 / Outer view of FES type pushbutton switches”, suggesting that “FES” originally denoted one specific family. The individual series were numbered FES-1 and FES-2. As later switch reed and mechanical series were introduced, their series names also carried the FES prefix. This includes the leaf spring lower assemblies, and the FES-360 discrete leaf spring and the related FES-370 non-leaf dome switch.

A Fujitsu keyboards advertisement in Electronics magazine in April 1976 refers to “Fujitsu FES-series snap-action key assembly”. The switches cannot be seen in the scan. From the description and the date, it’s not clear whether the advertisment refers to FES-5 or FES-8.

Keyboard series

See the series list page for details on known Fujitsu series and groupings.




For standard Fujitsu models, the N860 codes and FKB codes are directly equivalent. That is, FKBseries-variant maps to N860-series-Tvariant, e.g. model FKB4725-651 has N860 code N860-4725-T651.

The switches of some of the series (FES-1, FES-8 and FES-9) were marked with the part number and what appears to be a date code or lot number. No conclusive interpretation of the date code has been reached. The codes may be production dates, arranged as the last digit of the year, then the month letter (1–9, X–Z) with (in the case of FES-8 and FES-9) two additional digits. One FES-8 example has the “X” (in what appears to be the month position) printed as a full-width multiplication sign (“×”) instead of a Latin letter, which would be a strange mistake to make. An example of N860-8002-T06501A has a serial number from April 1982, and switches marked with codes that also suggest April 1982.