+1 for the very detailed and eminently reasonable answer! I wasn't aware (but probably should have) that a significant portion of the software is copyright encu

+1 for the very detailed and eminently reasonable answer! I wasn't aware (but probably should have) that a significant portion of the software is copyright encumbered because it was not officially legally abandoned. I think ideally the current copyright holders would release the source codes in question, both for reasons of preservation, and so that everyone gets the chance to explore these systems for themselves, on their own boxes at home.