ninstrument.com (dead now) built these in 2014, quote:
> We are addicted to PR8. Neil has done an amazing job with the layout and useability! He says this about it on his site, “PR8 takes everything and turns it on it’s head. It’s a drum-machine-style synth but is also so much more. Uses 6 ‘virtual’ tracks and the drum ‘instruments’ are able to use any combination of all of the NES’s hardware voices SIMULTANEOUSLY! Tons of features and 180hz refresh rate for fast pitch sweeps and other effects. And yes, it has Auto Echo too!”
Official posting of these carts:
- https://web.archive.org/web/20130719021
age_id=783
- https://web.archive.org/web/20130621172
audio.com/
- Manual: https://web.archive.org/web/20130213060
index.html
- Original Chipmusic posting: https://chipmusic.org/forums/topic/1445
nes-carts/
Youtube video of PR8 in action: https://www.youtube.com/embed/iqkOvHr0ytY?rel=0
NOTE: I don't have a working NES to test this on any more. It worked in 2014 and that was the last time I used it. There are internal batteries inside, they may need to be replaced. No returns.
➡️ EBAY LISTING: https://www.ebay.com/itm/285396781272