Never assume it was a bug in BASIC. A bug indicates it was a mistake. Very often code of that age had "tricks" to workaround hardware/limited resources that could be perceived as a bug when it kept something else from happening as intended, but it was required. That is the difference between a hacker then and one today- they didn't bitch and complain about bugs, they just made it work. I know you were coding back then- I was too, but I have a feeling you weren't well versed with the ins and outs of how BASIC interpreters of the time were written from reading things in your blog like:
"I’m not a programmer. Or a hardware guru. I’ve come to believe myself the amateur anthropologist. I like rummaging through the midden mound of the techpress reading what the tribespeople have to say. I’m bookish."