I just thought I'd pop in and tell you about our FM-YAM cartridge. The FM-YAM is a sound expansion for the C64, with YM3812 on board, build to be compatible to the SFX Sound Expander.

http://c64.xentax.com/index.php/fm-yam

We have released the second batch earlier this year, with over 220 units sold world wide to date. I've worked hard to keep the price at an affordable range, to 38 euros.

The unit is aimed at mixing the SID (via audio in on the cart) with the FM sound output (via audio out on the cart).

Here are some showcases:

Ed in his Lib, Jammer's new tune, released at X2018, composed in Edlib and Goattracker: https://www.youtube.com/watch?v=pmTTvUplLhI
Odie FM, a small collection of FM tunes, by Odie, using his new player: https://www.youtube.com/watch?v=_nJgvcA5td4
FM-YAM Music Demo Casu Quo, my cover of an old tune of mine, to test the balance of SID and FM: https://www.youtube.com/watch?v=dTyGnh0 … e=youtu.be
Vibrants FM, using the Edlib Player I coded for the C64: https://www.youtube.com/watch?v=Rh7wKVmw3vs
Sid Fishes, 13 channels of music (9 FM, 3 SID and 1 extra DIGI SID): https://www.youtube.com/watch?v=wbD9O0yFGZo

In terms of trackers, you can use Edlib for DOS by JCH, since I wrote a D00 (Edlib files) player for the C64. Currently, Odie is working on a new Windows-based FM music editor for FM-YAM as well.

Should you be interested, I still have a few extra cartridges left.