Korg PS 3100 - Signal Generator - Oscillators

The signal generator (SG) is Korg speak for the oscillators.
The different waveforms are TRI, SAW etc.

PWM, Frequency adjust... fine & coarse.

Immediately below the SG section we have the modulation section.

For this to be active push the right orange switch to "on".
Notice the reverse switch on the left.
This section allows you to route MG1 (LFO) , the GEG (General Envelope Generator) or some external modulation source to the SGs.
So you can frequency modulate. :-)