The Korg Minipops 7 is the ancient preset drum machine most famously featured on Jean Michel Jarre's Oxygene and Equinox.
It has a number of very basic percussion voices, triggered by preset patterns stored on a large diode matrix.
The extensive use of inductors in the circuitry makes it a difficult proposition for cloning, and attempting to reproduce the circuits substituting gyrators for the inductors would most likely strip out the character of the original.
But for reference here is the PCB: (click for hi-res image)
and the schematics for the sound section: