Well tonight I added an interface lead from the spare contacts on the integrator switch to the plotter. This allows the plotter sweep to be started when the TR-10 is switched out of "Reset" mode.

Wired up the TR-10 to produce sine and cosine by solving

dx/dt = y
dy/dt = -x

which have the solutions "sine(t)" and cosine(t)". These can be plotted against time to produce a sine wave, or against each other in x/y mode to produce a circle...

A sort video can be seen here:-