As you point out, the sorting of arrays and sequential access files (tapes) have different algorithms. the cost of access to a tape record is not negligible an

As you point out, the sorting of arrays and sequential access files (tapes) have different algorithms. the cost of access to a tape record is not negligible and it is the main cost. But for arrays/memory it's almost 0, the weight of memory access. Niklaus Wirth describes this in the classic book "(Algorithms + Data Structures = Programs)". There is a full chapter comparing the best/normal/worst case for each approach. Those were "Elegant weapons for a more civilized Age.".