I have recently started my second year at Uni and one of the areas I am studying is Digital Logic Fundamentals. However due to a mixup with my timetable I missed the first few weeks of the course. I am trying to catch up but have become stuck on part of the course that wasn't explained well in the online notes. Does anyone have any good resources or books that can help me understand this area especially understanding TTL's, Totem Pole outputs and just generally anything in that area? Thanks.