Ask HN: Any good MOOCs on Assembler?

I am software developer and currently using high-level languages (such as Python and JS) at work, and somethink I'd call `middle-level` for my side projects (Go, C#, some experiments with Haskell).

I have general knowledge about compoter architecture, how compilers work and so on, understand assembler code listings (given some comments), but I'm eager to have more experience with it and to read/write it `fluently` on demand (however I understand, that it is mostly for my interest and joy, not that I'd use it somewhere in my work), so I'm asking: can anyone recommend some good MOOC, or maybe just good article series (book is OK too, but some interactivity wanted) on this topic?

PS: I'm talking about x86 first of all, but it isn't restriction, of course.