It worked! My PR to ao486 MiSTer in case you're interested: https://github.com/MiSTer-devel/ao486_MiSTer/pull/145

AMAZING! I've been trying everything I could think of the last few days. I think the missing key is the last port read on address +2 is expected to return 255. This is not something my code currently does. Thank you!

Thanks guys! So my analog recording setup is a bit shit, resulting in a more muffled sound. The ZYBO only has a powered headphone output; my camera only has a microphone input. So it's pretty unbalanced. The DAC actually has a line-out; I could haywire the output over the headphone jack, and then …

https://github.com/gtaylormb/opl3_fpga