[pizza234]

You'll find a very good introduction in the comparch book "Write Great Code, Volume 1", chapter 12 ("Input and Output"), which also explains the history of system buses (therefore, you'll find an explanation of how ISA works).

Interestingly, there is a footnote explaining that "Computer Architecture: A Quantitative Approach provided a good chapter on I/O devices and buses; sadly, as it covered very old peripheral devices, the authors dropped the chapter rather than updating it in subsequent revisions."

[pedrolins]

Wow. Just skimmed across that chapter and that looks like a great resource. No wonder I couldn't find it in any of my searching sessions, I'd never think a book titled like that would cover hardware concepts so extensively. This will definitely help me in understanding buses better. Thank you.