The historical #chatbot#, #ELIZA#, has had its source code unearthed from the MIT archives. The therapist personality was just one of its personas, including one that could make passable small talk and one that served as a tutor.
Tomoyuki Nishita and Eihachiro Nakamae "Continuous Tone Representation of Three-Dimensional Objects Taking Account of Shadows and Interreflection", 1985