Yamaha YM2203 OPN
The Yamaha YM2203 is a sound chip used in many game boards. It as 2 Timers, 3 Software Soung Generator with Noise and 3 FM channels for music effects with 4 operators for each channel. Every operator can be mixed with others in different modes. Internally the chip has sine table stored in logarithm in fixed point number and before output every sample it translate te energy in linear value.