An update!
After months of nothing, hooked up an Arduino to a C64 connector, picked an organ sound and wrote a very rubbish program to play the first lines of a well known tune.  Have a look and listen at:

Arduino plays an SFX Sound expander

I know its a bit basic, but its a start.
Feel free to comment, but please make them constructive!


I know this is an old thread , but I've been working on a Dual sid + FM ( 3526 and 3812 )  music driver for a while now. Should have something out there very soon. Also in the process of modifying the C64 version of Bubble Bobble to play the actual arcade music if you have both a Commodore 128 and the FM cart. I did find complete documentation for the FM chips and the writing/reading technique as used by you guys is correct.
Will keep you progress posted,


Did you have to strip out any of the FM calls in the Bubble Bobble music?  I noticed it hits a lot of the registers kinda randomly.  (not as badly as Ikari Warriors though)


OK, mega necro bump here.
Announcing that after years of delays called real life, not one but two gadgets to drive the rare SFX Sound Expander have been produced!

First one features approx 100 sounds from the original C64 Software and some from PC Land, a DIN MIDI in and a 16 x 2 LCD.

Photos are here: … o-MIDI-V1/

A video of the uncased prototype in action is here:

Documentation and V1.5 to be released soon......


It would be cool to have some info on programming FM hardware on the C64 at if anyone feels like writing up something about that.


You may have missed these. FM-YAM features the OPL2 (YM3812). 300 cartridges have been sold so far.

A piece on the timing of programming the chip from the C64: … ite-timing



You can use Edlib to compose music (DOS) and then play the D00 files on a C64.

Check out also the combination of SID+MIDI+OPL2: … 2&t=0s

Last edited by Mr.Mouse (Dec 3, 2020 11:05 am)