I just found this free synth from Full Bucket Music in Germany. Enjoy!
 
https://www.fullbucket.de/music/fb3100.html
 
From the web page:
 
The FB-3100 is a software instrument for Microsoft Windows (VST) and Apple macOS (VST/AU) simulating the KORG PS-3100 Polyphonic Synthesizer from 1977. It is written in native C++ code for high performance and low CPU consumption. Main features are:

• Close emulation of behavior and all controls of the original hardware
• Band-limited oscillators, classic two-pole lowpass filters
• Resonators section
• Two Modulation Generators, Sample & Hold
• Additional paraphonic Envelope Generator
• Semi-modular patch panel
• Micro-tuning option
• Additional tweaks
• MIDI Learn – all parameters can be controlled by MIDI CC
• Plug-in supports Windows and macOS (32 bit and 64 bit)