More progress on my #Commodore64 #COBOL program -- the insertion sort works correctly now. In this video, I've just entered the last song on a second album, and you can see the progress of the chop sort and the results.

It's not straightforward, because first of all, only record numbers are stored in the index, so you have to read a record from the relative file on every compare. In addition, you're actually looking for a hole in the index, not a specific element. So if the new element is less than the compared element, read the previous record in sequence: if the new element is greater, we've found the hole (and the reverse if it's greater).

P.S. Please excuse the typo on "She's So Fine". Sorry, Noel!