Note: YM2151 is not anything to do with Sega 8-bit consoles, but it is related to the VGM format. The following is transcribed from scans of the YM2151 User's Manual found at NeillCorlett.com
Outline of Functions and Features
Outline of Functions
The YM2151 is an FM-type sound generator equipped with an 8 bit bus line and capable of producing superb audio quality via a microprocessor program. When this IC is used in tandem with the specially-developed YM3012 D/A converter, you can obtain 8-note, left-right/2-channel audio signals.
In addition, this unit is equipped with noise, vibrato, an amplitude modulation circuit, a sound effects circuit, and timer.
The package is a 24-pin dual in-line package.
- Generate up to 8 notes.
- Generate noise.
- Timbre can be altered temporally.
- High harmonic can be de-harmonized from the base frequency.
- De-harmonize between octaves.
- Interval settings of up to 1.6 cents.
- Add vibrato and amplitude modulation.
- Generate a variety of sound effects by extreme de-harmonization of the high harmonic from the base frequency and massive vibrato and amplitude modulation.
Summary of the Principles of FM-type Sound Generation
Construction and Features
Low Frequency OSC