Zumindest hat ein FB-user eine schlüssige Interpretation geliefert, warum es ein FM-Synth sein könnte:
Frequency modulation was first discovered by Robert Chowning at Stanford University between 1967 and 1968. It wasn’t patented until 1975 and was previously licensed to Yamaha in 1973. FM was actually first designed for to transmit voice over radio, which is how FM radio got its name.
After Chowning developed frequency modulation, engineers at Yamaha started using his algorithm to design the first commercially produced FM synthesizer. The team added improvements like the “key scaling” method to minimize distortion that normally occurred during frequency modulation. However, it would be several years before Yamaha started releasing their FM digital synthesizers.
Throughout the ’70s, Yamaha evolved Chowning’s initial discoveries and received several patents of their own. In 1974, Yamaha built the first prototype FM digital synthesizer, eventually commercializing FM synthesis technology with the GS-1—the first FM digital synthesizer, released in 1980.
FM synthesis was the basis of some early generations of digital synths, and Yamaha was at the forefront of their development. In 1983 they released the DX7, which is one of the most popular digital synthesizers ever made. It was on everything in the ’80s!"