Disclaimer: I am not officially affiliated with QuBit, and my thoughts/opinions are my own. However, I did help QuBit out a fair bit when the company first began, and can provide some insights about the development of the first Nebulae.
Some background: I introduced Andrew and Jason to the Raspberry Pi back when it was being developed at Berklee, and also gave them advise for how to get started building the firmware for the Nebulae. I also was the one who got the initial PD support working on the device. (Oh! And that’s me playing the bass and ukulele in the QuBit sample pack.)
So, as for the “intent” of the Nebulae: The original idea behind the Nebulae was to use Csound as a synthesis engine to build a eurorack module. Not a reconfigurable module. Not even a Csound module. Just a module that incidentally used Csound for the DSP. In this case, this module was built around the Mincer and Paritekkel opcodes. I think this design choice reflected CsSpectral, an iPad synthesizer being developed by Richard Boulanger (and us), which used Csound as the underlying synthesis engine. We were very used to the concept of using Csound to build synths.
Shortly after building the initial prototype for the Eurorack, Andrew and Jason published a paper in the Csound Journal on building an FM oscillator using Csound, Pi, and Arduino:
Note how this specifically talks about building an FM oscillator, and not using Csound in general. We were testing Csound on the original Raspberry Pi model B, so there were restrictions on which parts of Csound you could use. Things like sampling and FM synthesis with limited voices were all that you could really do. I actually remember being very impressed that they could get something as complex as partikkel running on that thing. AND Mincer!
I think extendability was always something that was going to be there, but as sort of an afterthought. Sort of a “it’s there, so we might as well” kind of thing. It was full-on Csound. It was running Linux. Why not? The original concept there was to allow people to just load their own Csound patches. PD support only came after people were requesting it. It was never part of the original vision. Luckily, it was just Linux, so most of the groundwork was in place.
Linux, by the way, was definitely a means to an end. It was an easy way to get Csound running on an embedded system. If we had figured out how to get Csound running as some kind of realtime OS, we’d probably would have gone with that. The big picture idea at the time was to get Csound into Eurorack, and that was basically it.
The Nebulae was designed as a phase vocoder + granular synthesis module, kind of like how the TB-303/TR-808 was built to be a band-in-a-box for singer/songwriters. QuBit did a very good thing when they decided to let people reprogram the Nebulae. By making the Nebulae hackable, they gave it permission to grow and evolve beyond the intentions of the original creators. I imagine people will find new uses for it for years to come.