FYI, the fine people at #archiveorg have a nice collection of Apple Orchard magazine scans.
Numbers V4N3, V4N5 and V4N7 have a series made of 3 articles on direct programming of the Disk ][ interface, which I'll peruse to play around with my clone for the TK2000.
https://archive.org/details/Apple-Orchard-v4n3-1983-Apr