There are external classes like IDEC or SW-SOC, but in the case of IDEC, since the two professors try to convey a lot of content concisely, there are many cases where it is difficult to understand. But you can't watch it again. In the case of SW-SOC, it's a seasonal system? You register for the lecture (I don't know why you have to register for the lecture when they just repeat what was taught before in the case of online lectures). They are either very job-related lectures or very simple lectures. Honestly, reading the book is more helpful. This person's lecture is explained based on example code from the perspective of a current employee, so it's understandable and it really helped me a lot when designing FPGAs. Highly recommended! Thank you, Matbi.