This model is used to simulate the activation of Purkinje fibers. The Purkinje cells are auto-oscillatory so there is no need to use a stimulus to produce an action potential. However, changing parameters can change the dynamics from auto-oscillatory to excitable. For example, change gna from 0.14 to 0.12. Then try setting S1 to 10 ms and S2 to 400 ms, 500ms, or other values.
As in the Hodgkin-Huxley and Beeler-Reuter applets, all the gate variables of the model can be plotted along with the voltage.
The model can be found in D. Noble, J. Physiol., Vol. 160, 317-352, 1962.