This is the first post in a series on emulating the main Sega Genesis sound chip, the Yamaha YM2612 FM synthesis chip, also known as the OPN2. To date, the YM2612 is pretty easily the most difficult-to-emulate sound chip that I have worked on. It’s not extremely complex in concept, but it has an incredible amount of specific details and quirks in how exactly it works, and many of them need to be emulated exactly correctly for game audio to sound correct. Debugging mistakes is also very, very dif...