I am analysing the contents of the OPL4 ROM, and it seems I am missing something. There're instruments overlapping each other (316 to 330 overlap other instruments), and I calculated 626 kB of unused space (out of 2 MB), not related to any instrument with proper layout. At the same time these unused locations contain some non-uniform bytes. Invalid instrument 330 refers to the wave data with "YAMAHA.YMH" in it, which must not be valid wave data.
Anyone have done this ROM analysis before? Findings?
I needed 24 bytes at the end of the ROM. It appeared that there're only 4 unused bytes at the end, and they are also not actually unused, but identifiers of the ROM version. And second task was to validate the contents and ensure I understand the layout.
