The synth sounds are generated in script - I cannot take full credit for this, its been done before. But its a fun trick.
So if you go mad and play a lot of notes, you use up more memory! A small price to pay for bleepy goodness.
Once I have got the sequencer bit working, I will make it so the sounds and tunes you have made can easily be downloaded, saved or shared.
I love old CHIP / SID music, so hope it will encourage people to make some using this tool for their games and whatnot :-)