This shows off an emulation of the Casio CZ oscillator, which was genius. We take just a single sine wave, and adjust its frequency and amplitude to warp it into something that sounds like a sawtooth. We then alternate that with different frequency and amplitude modulation that simulates the effect of a resonant filter. This complicated AM/FM'd oscillator is contained in a "package" which acts just like the built-in modules. So, without understanding its inner workings, you can use it in any patch as simply another oscillator type. The Moselle package supports all three resonance waveforms of the original, and the five basic CZ waveforms (warping to a sawtooth, to a square wave, a couple kinds of pulse waves and double pulses) plus a few more that the original inspired.
Note the sound is recorded directly from Moselle: no hardware or external processing was used.