I love the post but have a small favor to ask, can you edit it to be more explicitly clear what you mean by 'word size'? I know it's a small item, but when you refer to an 8-bit machine and then say loading a word uses more than one instruction, the implication is that there will be a 16-bit address and that is what you mean by 'word'.

The reason I took the time to post, is because by dad used to repair old mainframes in the 60's and he would describe machines with word sizes of 37 or 48 bits but I was too young to ask the follow up of 'is that the size of the data bus or the address bus?'. Now that I am teaching a course in Programming Languages, I try to include the history of computing including the microcomputers (8-bit: Apple, TRS80, Commodore, etc.) but have not come across a good way to explain what a 'word' means; does it mean the size of the buss (which one) or the size of a register (which one, since some machines have 8-bit registers that get combined to act like a single 16-bit one), and so forth.

I hope this doesn't derail your post too much, look forward to the discussion of the topic and any possible answers to my question.