Morph from square to sawtooth, with some kind of funny PWM.
set OSC1 wave to pulse/square
set OSC2 to sawtooth, one octave +12 semitones up
set both OSC1 and OSC2 to phase lock (tab two display knob 3
set OSC2 volume to half of OSC1
assign OSC2 level/volume to a controller. The more you lower OSC2 level the more pulse/square it is.
for PWM: control both OSC1 and OSC2 sdhapemod with the same controller, maybe in different amounts. It's not the same as sawtooth shapemod.
Why? It's from additive synthesis. If you stack up lots of sinewaves in the harmonic series: note, one octave up (note frequency times 2), one octave and a fifth (note frequency times 3) and so on, you get typical wave spectra. Wave forms differ in the volume of the harmonics and to some degree in the phase of the harmonics.
A sawtooth wave has all harmonics with a volume of 1/n, n being the harmonic: note = 1/1 = full volume, harmonic two (one octave up): volume = 1/2 = half volume, then 1/3 of full volume and so on.
A square wave only has the odd harmonics: the first, third, fifth and so on. Though at the same levels so at 1/3, 1/5 and so on of full volume.
If you pitch a sawtooth one octave above a square, it's basic pitch will be the second harmonic to the square. At half the volume it is correct for the sawtooth (second harmonic, volume = 1/2 of full volume). The next harmonic of the sawtooth is the fourth harmonic to the square wave. So the saw will cover harmonics 2, 4, 6 and so on. It will also have the correct volume.
I tried it and it works well.