The tiny LCD UI was a typical cost-cutting measure for synths from that era and isn't unique to FM or even digital synths. I bought a vintage Yamaha TX81z (the

The tiny LCD UI was a typical cost-cutting measure for synths from that era and isn't unique to FM or even digital synths. I bought a vintage Yamaha TX81z (they're cheap on ebay) and while it features a tiny LCD UI it also comes with a very logical diagram printed on the top of the case. Yamaha's user manuals are also well written. I've enjoyed making dozens of FM synth patches on all sorts of instruments (perhaps because I am attracted to the FM sounds that you still hear all the time in pop and dance music.) At the end of the day most synthesis methods boil down to two knobs: signal amplitude and spectral complexity, and FM isn't that different, especially with a single oscillator/operator pair.