On loading of a saved game, the Prelude continues playing instead of the proper theme for the area.

[Dylan Morrison]

When a saved game is loaded, the Prelude continues playing instead of the proper theme for the area. This is due to two seperate issues. One, the RAM used for keeping track of current playing track is actually used for another variable which is sometimes overwritten during saving, and two, the currently playing track variable is saved along with the rest of the first 8KB or so of memory, and thus when the MSU routine checks what track it is playing against what track is requested, it thinks it's playing the area track when it's playing the prelude.

[Dylan Morrison]

This issue (that is to say, both known causes of the issue) are preliminarily fixed in the Experimental branch. We are now using $1E20-$1E27 instead of $1E00-$1E07 for keeping track of up-to-the-minute MSU data that we want to be present during a saved game. In addition, $7EF001 is now used to keep live track of the last track pushed to the MSU-1's track registers, which is not within the area of memory kept by a saved game. This is now what we compare against to see if we're playing a track.