File IO was extremely hard on the early home computers, so it was very unlikely to have the ability to save and load the tree. And with such short code, there's no way to balance the tree either.
The Apple //e version absolutely saved and loaded the tree. I played it just last month with my niece and nephew and it loaded the same ridiculous questions my sister and I had inputted as children 30 years ago.
Rebalancing is not possible not due to code restrictions but due to the nature of the game. How could the program know what new labels to invent for the inner nodes of the rebalanced tree? Unlike integers, animals are not totally ordered.
I had some version of Animal on our Apple IIe in the 80s, and I'm pretty sure it had the ability to save the tree. I have vague memories of the disk drive whirring after it asked you to provide a differentiating question. Unfortunately I don't have my later Apple IIGS up and running to prove it.
But I did find this BASIC version for Atari computers, from Antic magazine in April 1986. The article specifies:
"It's vital to save your computer's knowledge base to disk or tape - this knowledge is what makes the game fun. To save, type [CONTROL] [S] and you'll be prompted for a device to save the file to, and a filename. Cassette users should simply type C: at the prompt. Disk drive owners type D: and then the filename. To LOAD a previously saved knowledge base, press [CONTROL] [L] and respond to the prompt as explained just above."
The .BAS file at the end doesn't seem to be a plain-text listing, it's probably a saved Atari file. But viewing it in a hex editor, I see strings in the binary file like "Shall I SAVE this data?"
I remember having this book or similar (at least I remember the robot and the person from the cover) and recall that some things just aren’t portable across all BASIC implementations.
I think ZX Spectrum was what I saw most often, and there would be a couple of things that just didn’t work in CP/M basic, gwbasic or whatever I was using at the time - I imagine file manipulation was avoided for that reason also.
> File IO was extremely hard on the early home computers
Speaking as someone who was there at the time: no, it wasn't. Opening a file, reading/writing data to it, and closing it was a straightforward set of operations on the C64 I had. The I/O was slower, of course.
