Patch Base version 2.2 is available today, adding a new editor for the Yamaha FB-01. The FB-01 is another old 4-op FM synth from Yamaha, similar to the DX100 that I added an editor for in Patch Base 2.1!
The FB-01 has no way to program sounds on the machine itself, which I think is a reason why you can still buy these synths for pretty cheap. I bought mine for about $60. A lot of people see the FB-01 as just a box with a handful of cheesy brass and electric piano presets from the 80's. But with Patch Base, you can create some very out there sounds. The actual engine in the synth can do just about as much as the DX100, except the sound is definitely a bit more crunchy/lo-fi.
Here's a video showing a little bit of FB-01 editing with this new Patch Base release: