PLL: glitch-device extraordinaire. You feed it a simple oscillator signal, and the PLL will lock to it to drive the module's internal VCO/F/A circuit. But feed it weird things, and it goes NUTS. Mistracking, craziness...like the MS-20 percussion thru input trick on 'roids!

And VCAs that can do linear and exponential are great...expo for audio, to follow how we percieve 'loudness', linear to screw around with CVs.