I mean the logo at the bottom right of the title screen. Also I would like to see some source code too.It will need to run on every scanline or it probably won't sound very good. I didn't expect it to work during the FSS logo, anyway, just the title screen.
18 cycles seems quite a lot. Definitely not possible during the FSS logo. Can you update every 2nd or 3rd frame instead? How would your code look like?
512 bytes has to be possible somehow.