Gaming How do sound effects work on M4A GBA sappy games and what limitations are there?


Well-Known Member
May 4, 2020
United States
After I changed the value of one of the 00 02 01 00's to 00 02 02 00 then problems start to arise. I was just trying to get one sound effect to use both square 1 and square 2 and now something weird is going on, for example sometimes one of the sounds linked to the 02 01 (now changed to 02 02) value will play twice for no apparent reason while another sound effect doesn't play at all.

When I initially changed this value to 00 02 04 00 then the sound engine lost it's mind with this group of sound effects. Some of the sounds would not play at all (or would play improperly) while others would either play to fast or to slow, and some of the sounds effects would play the wrong sound for some reason. What's going on here? All I was trying to do was get more out of the GBA Sappy engine and now it's freaking out and I don't know why, also what do these bytes "00 02 01 00" mean exactly? All of the sound effects I created are sequenced sounds and most use the PSG channels while one uses a sample for the sound effect while all other sampled sounds the game plays were in the base game. Any insight into this problem would be appreciated.

(I forgot to mention that the music is not effected by this.)
Last edited by biolizardshadow,
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