Actually, the memory mapped approach of the C64 is an abstracted API. It’s so immediate and intuitive, though, I can see why you might not think of it that way.

Actually, the memory mapped approach of the C64 is an abstracted API. It’s so immediate and intuitive, though, I can see why you might not think of it that way. (I started on the Pet and later th C64, and had so internalized this approach that I was baffled when I first encountered systems where this wasn’t the primary approach.) I think there’s actually a lesson here for API design today: the power of the “everything’s-a” approach. Then it was everything’s a memory location. But generally the everything’s-a approach allows for a flat abstraction space with low cognitive overhead and high inherent/automatic composability, leading to short learning curves and high productivity.