This is a history of Earthbound/Mother 2's sound driver, which is identified elsewhere as N-SPC/Hirokazu Tanaka. There are four known SPC-side builds, used in three games.

• Two builds: one unique to the beta, and the other ones are for the final versions.
• Every audio effect executed through here is accessed through a raw ASM snippet instead of using a header. In Earthbound/Mother 2's case, some of the more commonly used cases are instead done via a header ID byte and other data, though one can still run an ASM snippet or two if they wish.

• This is the main version within the context of PK Hack.
• Contains some leftover Mario Paint ASM snippets that are unused.
• Unlike Mario Paint, this one uses a header system for its audio effects on the other three SPC700 ports.

• The $F0 and $F1 commands from port 0 (pause/unpause music) have been cut.
• TODO there are at least some other minor modifications since I saw a few new variable memory locations or two, not counting relocations…