The Yamaha DX7 synthesizer's clever exponential circuit, reverse-engineered

.hilite {cursor:zoom-in} a:link img.hilite, a:visited img.hilite { color: #fff;} The Yamaha DX7 digital synthesizer was released in 1983 and became extremely popular, defining the sound of 1980s pop music. Because microprocessors weren't fast enough in the early 1980s, the DX7 used two custom digital chips: the EGS "envelope" chip generated frequency and envelope data, which it fed to the OPS "operator" chip that generated the sound waveforms. A key part of the OPS chip is an exponential c...