The MD-8 is an interface for connecting MIDI synthesizers (for example, the JX-3P or JUPITER-6) and DCB synthesizers (the JUNO-60 or JUPITER-8). It features a Function select switch to determine the direction information is to go and an MIDI channel selector to specify which MIDI information the DCB requires.

It is also possible to change the patch memories of the JX-3P or the patch preset pairs of the JUPITER-6 or JUPITER-8 by MIDI or DCB in formation. The MIDI THRU jack also enables one more MIDI synthesizers to be connected.