Mitsumi Electric Co. Ltd. (ミツミ電機株式会社) is a Japanese electronics manufacturer. Mitsumi produced most of Commodore’s keyboards, as well as many of Apple’s keyboards. The logo on older products is the word Mitsumi itself, written in katakana: ミツミ (mi-tsu-mi, /mʲi.tsɯᵝ.mʲi/), which can be misread as “SMS”. Note the syllable breaks: “mi-tsu-mi” not “mit-sumi”.
On the 27th of January 2017, Minebea and Mitsumi merged. Minebea is now known as MinebeaMitsumi Inc., and Mitsumi is now a wholly-owned subsidiary of MinebeaMitsumi.
- Standard mechanical (KAx, KCx)
- Standard type 2 tactile
- Standard type 2 (anomalous version)
- Rubber dome and buckling rubber sleeve
The Commodore SX-64 keyboard uses what appears to be KCD Type, based on the KCD-A65YU membrane part number. The same type was also found in the Cardinal CP600, in this instance lacking the typical Mitsumi manufacturing date label.
When the Commodore 64 was introduced in 1982, the alternate action switch on its Mitsumi-made keyboard used a PCB for the stationary switch contact and the external connections. This switch is connected by inserting bare wire through holes in the PCB and soldering. These switches can however be used with PCBs, as seen with the Okuma Howa HC 74300 keypad.
Most details on Mitsumi series (KSD, KCQ etc) are presently only covered on the Deskthority wiki.
Possibly not Mitsumi
There is an unidentified switch with a design resembling a Mitsumi mount variant of the KCD Type switch used in the Commodore SX-64. This switch can be seen in the Nakajima All AX-240 typewriter as well as an unidentified typewriter. The matrix PCB of the AX-240 bears what appears to be the Matsushita logo, suggesting the actual manufacturer.