Another series that really helped me was Leventhal's assembly language series. The problems in the books were relatively simple but they gave you a hold on one CPU if you already knew something about another and they served as instruction set reference as well (which were ridiculously hard to get here in Europe, and I don't mean those little cards but the full data sheets).
Between that and a book on parsing I managed to cobble together an assembler and an editor together with a friend.
Oh, and in the list of machines I forgot the ST, the first machine that I had with a megabyte of RAM.
These days it's almost painful to come across great books that would have been so awesome to have in like 1984.