Well... arpeggio's are already a possibility :S
(btw:A soundchip for ti84 would be sooo cool! I'll check out what I can fix. I made a jackplug converter and I modified a set of earphones so a soundchip will be the next step
)
Edit:I disovered that the nes sends envelopes from it's cpu to the soundchip
We need to emulate this by converting variables into different output voltages in the linkport