It's been a few years, but I can confirm that when I took them in the 80's, Calculus AB and Calculus BC were two separate year-long courses. At my high school, you weren't allowed to take BC without having taken AB first. The pace was excruciatingly slow for me. But I did get 5s on both tests.
This is not what is written on the AP board. While I didn't take either (as I went to college a year early instead.) When I was in H.S. in the 80's AB and BC were two different option, you took one OR the other. Clearly they can be taught that way..
From the wikapida page on AP Calculus
The College Board intentionally schedules the AP Calculus AB exam at the same time as the AP Calculus BC exam in order to make it impossible for a student to take both tests in the same academic year, though the College Board does not make Calculus AB a pre-requisite class for Calculus BC. Some schools do this, though many others only require precalculus as a prerequisite for Calculus BC.
