"- Your music code cannot access any I/O registers outside of $D400-$D41B." This should probably be up to $D41C, which is the last SID register (voice 3 ADSR output)?
Also, everything from $D420 to $D7FF is just shadows of SID registers.
im wondering. is it too much if i for example just make a simple PETSCII and add a Scroller as an executable?
So in short, the tune can utilize the ZP from $08 to $FF in any way it sees fit (temp variables, player code, music data)?
Covers and tiny adaptations of other SID tunes ARE allowed.
as a non coder. what would it require for packing options in GT?
That does work, until the user has extra SIDs installed... or maybe it's not a big deal. Before I actually allow it I'd like to hear from people who actually have this stuff installed on their real machine, if it makes life inconvenient for them that SIDs go writing willy-nilly into the mirrors.