My favorite Synth-Youtuber Alex Ball put out a really nice, comprehensive history of Roland, touching on everything from the RE-201 to Boss to all the Synths and Drum Machines. And he can actually play and use most of the stuff because he's a composer. Obviously he put a huge amount of work into it:

The old Roland Cubes are reliable, great-sounding miracles.Jeffrey Nadrich

Thanks! Just finished watching this. A great and concise overview that somehow manages to squash half a century of groundbreaking products into a little over an hour.