Yamaha has developed tons of sound chips, and they often bother chip researchers since many different lines get snarled up in close numbers. So I tried to ravel them on the following chart.
* Yamaha has used their integrated circuits for frequency modulation synthesis since the first models called GS1 and GS2 which consists of 55 ICs. Later ICs were decreased to 5 or 6 on CE20 and CE25. But I cannot find any informations about chips they include.
* Numbers before YM21280 were also used for home keyboards etc. But line-up and functions are almost unknown. So I started from YM21xx series. Some of you might have noticed that YM chips change directional character in every 100 (or 200) unit. Here're my complements:
YM3812 is an advanced version of YM3526 which allows you to select 4 basic waveforms. In 1986 it first appeared on arcade games, and later adopted to the famous Adlib sound card. Some sources state that there was a compatible chip called YM3814. But I cannot find farther informations.