I've been taking the course "From NAND to Tetris" on Coursera. So far, the course has been very interesting, and I recommend it. It provides a good taste of how computers work from a low level, starting at the most basic logic gates and building up from there. I'm over half way through, and have some observations.
- This course has been a blast! Slowly building up a computer from first principles has been very rewarding. Its an amazing feeling to struggle with designing a chip and then to turn around and use it in another, more advanced chip!
- The course hasn't been that hard. Now, I had some classes that dealt with this kind of thing at Pitt. I remember working with most of these concepts in the past, so this is not totally foreign to me. However, I also think that the professors did an excellent job simplify things to their essential concepts.
I'm really glad I have invested my time into this course. If you want to learn more about how computers work on a low level (or even if you would like a refresher into the topic), I highly recommend it.