Comment by Rochus

An another lot of people doesn't know that Smalltalk-76 onwards implemented the Simula 67 object model (as the first language in the given completeness), which represented a fundamental departure from Smalltalk-72. See the Ingalls 1978 and 2020 papers for more information (https://dl.acm.org/doi/10.1145/512760.512762 and https://dl.acm.org/doi/10.1145/3386335, both more interesting and relevant than the one in the title, written by the person who invented most of the technology we today know as Smalltalk-80).