Note by @fastfinge

@hosford42 The sourcecode for dectalk is out there. Unfortunately, It's...legally dubious at best. It was leaked by an employee back in the day, and now the copyright status of the code is so unclear that nobody can safely use it for anything, but also nobody can demonstrate clear enough ownership to submit a DMCA and get it taken off github. GNUspeech is also pretty close to what's needed, but it won't even compile without all the NeXT development tools, I don't think. So at best all that would be is a base for something else; modernizing it would probably effectively be a complete rewrite anyway.