I have received today a vintage NEOS MS-30 mouse. Designed for the C64 in the early 80s, it is in good condition for its age. No guarantee that it is working, but for the price, it was well worth it.
This mouse is not going to be used with a C64, instead it will be used with an adapter cable and my Tatung Einstein.
These mice were supplied by EMSoft with a 9 pin to User port adapted for the Einstein, to be used with a package called Mouse Art.
All I need now is the adapter cable schematics so I can make my own!