Yamaha DX7 chip reverse-engineering, part 4: how algorithms are implemented - Ken Shirriff: http://www.righto.com/search/label/dx7?max-results=20
Yamaha DX7 chip reverse-engineering, part V: the output circuitry: http://www.righto.com/2022/02/yamaha-dx7-chip-reverse-engineering.html
Yamaha DX7 chip reverse-engineering, part 6: the control registers: http://www.righto.com/2022/02/yamaha-dx7-chip-reverse-engineering_7.html