I don't remember how many credits. All I remember is that we had to have x number of classes in each of the disciplines (English & Lit, History & Gov, Math, Science). PE was required every semester. Certain classes were required in each, and then you chose from a few others for the rest of the credits in that discipline. I was one class short in science after my first semester senior year, so my second semester, I took Psychology. I also took three choir classes, a drama class, a mountaineering class for PE (we rappelled down the bleacher stacks) and a study hall, which I spent with my BFF in the cafeteria, playing partner Spades (a card game) against all comers. We had a pretty fine win/loss record.
In short, my last semester in high school was a freakin' blast.