4 x eoc (end of cycle) pulse outputs corresponding to the 4 function generators.
vc of attack and decay (with attenuators) of all four envelopes
2 x analog or (aka peak circuit) logic outputs that are normalled to the two pairs of envelopes (1+2 and 3+4) with attenuators.
special quadrature modes for envelopes 1+2 and 3+4 with jumper on pcb to select two different kinds of looping responses.
connects to the quadra via 4 ribbon cables
12hp and skiff friendly