Initially sold for ¥230,000
The Yamaha MDR1 music disk recorder is a small add-on of Electone organs that allows the recording and playback of performances. Digital data can be stored or loaded from compact floppy disks (not standard 3.5" floppy disks). A flap on the bottom left hides some additional recording controls and knobs for transposition and tempo.
Two version of this device exist: the MDR1A has a bracket to be mounted below the Electone FX1, while the MDR1B has extra components to be mounted inside the other supported models (FX10, FX20, FS20, FS100, FS30, FS200, FS50, FS300, FS70 and FS500). 5 floppy disks were also included in the package.
The manual mentions the compatibility with Clavinova performances as well, but in 1984 no Clavinova had support for disk operations or even data connections. Since the MDR1B comes with extra wiring and boards to add data support, it may be assumed such operation was also possible on some Clavinova models.
Yet the weirdest thing is the inclusion of the YIS logo. The 1982 advertisement for the YIS ecosystem mentioned the future availability of a device to connect Electone organs similar to what the PC1 did for pianos: is this it? Can this be the miniaturized and updated version of the device promised in 1982? However, this is 1984: Yamaha was already reusing the name of the YIS303 and YIS503 MSX computers having scrapped the idea of a real home system. And the MDR1 doesn't show any connection with computer whatsoever.
With the following release, the MDR2, the logo disappears and the 15 pin proprietary interface eventually gets replaced by MIDI.