So, I've decided that I want to try and replicate this analog instrument and throw in a few more features to it. The problem is, I have no idea how to create it's "square" wave. It doesn't even remotely look like a square wave, to me. Anyways, here's a picture of what this wave looks like:

The top wave is the TB-303, the bottom part is some guy's digitally-generated model of it. I think it's a pair of saw waves, one ramp-up and one ramp-down, used in subtractive synthesis and fed through a waveshaper of some sort. Can anyone confirm this at all? I really want to make an accurate model of this synth.