Hi Matt I don't have a GP-6 or GP-10. I do have a EC-1. I would suspect that you could do the bouncing ball simulation with the GP-10 ( I assume that means it has 10 op-amps ). The things you need besides capacitors and resistors is a couple of diodes for the nonlinear things ( like the ball bounce on the ground ) and sine/cosine source. The computer needs reset relays to set initial values for the integrators and pots to generate the constants. The HeathKit has you make an external sine/cosine source, using 60Hz from the wall. This typically doesn't do vary good with the noise that most modern equipment has, since they make the 90 shift with a highpass. The original Heathkit example used 9 op-amps but I came up with a way to do it with only 8. This leaves two to make a sine/cosine oscillator. I'll have to dig up the schematic that I put someplace. You can live without the sine/cosine, since it is just to make the ball round. To display, you need an oscilloscope or a X-Y plotter. As for setting the unit up, I suspect there is a balance adjustment for each op-amp. For my tube machine, I found that I had to balance the integrators for zero drift instead of zero voltage offset. I suspect that this is because input current offset and input voltage offset are not the same thing. Dwight