The VM928 is a sample and hold with an internal clock source and a glide section.
Below we've illustrated how a sample & hold works. In the image below, the smooth gray line shows a continuous input signal. Each time the module is triggered by an incoming clock signal, the current voltage is “sampled” and “held” until the next trigger. The red line shows the stepped output signal.
Inputs, Outputs, and Controls
Clock Rate- Sets the speed of the onboard clock from 0.3 to 30 Hz.
Trig In- Patch external trigger (i.e. clock) signals here when the Sampling switch is set to the Ext position.
Sample Int/Ext- Selects either VM928's internal clock or an external clock source. Typically you'd use a sequencer or clock module, but just about any module that outputs a waveform with a sharp leading edge can be used as a clock source.
Clock Out- Outputs the internal clock signal, either as a pulse or a triangle wave.
Glide- Smooths the stepped output of the sample and hold. Lower settings are faster, higher settings are slower.
Inputs / X1/X3- This is where sample sources are plugged in; each input has a different mod depth. The X1 input is about 1/4 volt up and down, and the X3 input is about 3/4 volt up and down.
Outs- Sample and hold outputs. Even though they appear to be related to the X1 and X3 outs, they aren't, they are just duplicate outputs.