The mini-assembler was still available from Integer BASIC on II+ and IIe. It returned to ROM for later IIe models.

It makes sense that I didn't find it. Integer BASIC didn't make sense to 10 y/o me, either. I'd started with Applesoft, since it was in ROM, and Integer BASIC seemed needless and strange. I also didn't understand why "FP" was the command to get into Applesoft.

(These are yet more examples of situations where, if I'd had a mentor, I think I would have gone much further at a younger age.)