> Is there a way to add the non-linear transfer function as an add-on

module

The miniwave module does the non-linear transfer. And that's how it's
working.

Analog Input #1 is converted by a 6 bit ADC (analog-to-digital converter)
into a six bit "word" (range 0...63, the PPG waveforms were only 64 in
length). This is used to address the first 6 address inputs of a memory
(normally a ROM or EPROM). If a standard sawtooth wave is used and the
offset and amplification adusted accordingly one obtains the standard
wavetable synthesis. But even other waveforms or not an accordingly adjusted
sawtooth may be used to obtain special effects (e.g. picking out only a
fraction of the complete wave). A second ADC (normally controlled by a
modulation signal, e.g. from an ADSR or LFO or ...) is used to generate the
higher addresses for the EPROM. This control voltage is used to scan through
the different waves. Switching from one wave to the next can be independent
from ADC#1 or triggered by ADC#1 (e.g. waveform switching is allowed only at
the maximum or minimum value 0/63). In the first case the wave can be
altered even in the middle of a waveform. In the second case the end of the
wave has to be reached to allow the switching to a new wave.
Finally a rotary switch (e.g. with 16 positions) can be used to select a
waveform set.

The module could be used also as a CV processor if ADC#1 is fed not with an
audio signal (e.g. sawtooth) but a slowly changing control voltage (e.g.
ADSR or LFO).

As said before: not very complicated from the technical point of view. But
without good wavetables it's nothing ...
And we do not want to get troubles with wavetable copyrights (provided that
there are copyright)

Best wishes
Dieter Doepfer

(P.S. Maybe we have a lawyer in the group who knows details)