Current version of PNtalk system was implemented in 1996. It was embedded into Smalltalk (VisualWorks) system. From 1997 to 2000 it was significantly improved mainly to reach better stability of its user interface. But it slightly differs from today's version of OOPN definition and PNtalk language - synchronous ports are not implemented. It has so-called predicates instead. A predicate is a kind of synchronous port without side effect (only for testing object's state).
Current PNtalk implementation in Smalltalk has its own WWW pages prepared by Tomas Vojnar:
Note that the main purpose of this PNtalk system implementation is demonstration of the OOPN priciples. Now we are working on a new PNtalk system implementation which will be better suitable for serious applications. Since the new PNtalk system implementation (PNtalk 2000) will not be available before 2003, the current implementation will be further maintained.