I'm a CS major, and I purchased the book to review CS comprehensively for interview preparation during my job search, and I also took the course as a way to review the book since lectures were available. The author has published three CS books: Computer Architecture + Operating Systems, Networks, and CS for Interview Preparation, and I plan to take all of them. First, regarding opinions that the lectures are just reading the book, I agree, but I think for a free lecture, this quality is quite good. I think it would be even more effective to read the book first, then review and organize while listening to the lectures. Even though I'm from a university in Seoul, Computer Architecture and Operating Systems aren't subjects that are studied in great depth. Especially for Operating Systems, even when taught with the dinosaur book, each section goes so deep that it's hard to understand all at once, and since you have to rush through the material in one semester, you forget everything after it's over lol Universities usually start from logic circuits and teach Linux too, but even when taught and learned with English materials, professors lecture on peripheral details, so it's hard to understand all at once. However, this book and lecture exclude those peripheral details and teach exactly what's needed with an introductory feel, kind of like a sophomore-level course. I think it's efficient to use what you learn here as a foundation, then study only the parts that will appear in actual interviews while looking at CS interview books. Lastly, I think my college life would have been a bit easier if I had known about the author's books and lectures when I was in university..ㅜㅜ Not all professors have good teaching skills. Great lectures, thank you