[sdiy] Daft Idea, LINUX SYNTH

[Paul Maddox]

Rainer,

> My opinion on that: Forget about the processor discussion at first place.

I say forget it all together...

> Taking the modular approach boards will eventually come with their very
> own processor doing dedicated stuff (e.g. real-time filter calculation,
> fx processing etc.) which is completely independent from what the main
> controlling unit has to do. So the initial discussion is less "what
> processor should I take" but more like "how should this interconnection
> bus look like" (where I'd favour the good old 68k approach with UDS/LDS
> making it possible to have either 16 or 8bit bus width).

well said!

> The modules can use whatever they want and be programmed in any way - all
> they have to provide is some control and status registers to allow the
> main CPU to parametrize the module. Here, of course, standards of
> operation and intercommunication need to be defined (PIO vs. IRQ vs. DMA -
> where my voting goes towards PIO since it's the "least common multiple"
> making each module just a batch of registers somewhere in the memory map
> of the main controller which under all circumstances will keep the
> control over the entire system).

This I agree, with each module should have a simple pile of registers which
can be read/written to by other modules..
I mean imagine haveing a modular where you can route ANY signal to ANY
parameter, not just any input to a module...

> The main controller, however, needs to run a lean, efficient RTOS to cope
> with MIDI messages, user interaction (controllers) and sound synthesis
> rules in real time. That IMO can be done almost in C which makes porting
> the stuff to the processor if choice is much easier than writing
> everything entirely in assembly language.

errr, why have a main controller?
Why not just have midi modules?
The main controller can just be sat overseeing the whole thing, makeing sure
each module gets its correct time slot and behaves as it should..

> As you can see, my vision of this OpenSynth is a most modular and very
> multi-processing approach where the sound generation is distributed among
> all attached modules, the main controller just takes care of proper
> parametrization of these.

BINGO!
Thats what I was meaning, though I cant phrase it quite aswell!

> There are a lot of ideas and concepts floating around which - if they'd be
> put together in one big project - could really give some sort of monster
> synth. I'm quite sure, that RTOS is already written. And for sure there
> are many interesting DIY projects out there, some of them being pure
> analog stuff (like those being discussed here), others are hybrids,
> possibly another bunch purely digital like IIR filters, effect modules
> etc.

Dare I mention 'DSP'?
<hides under table>

Paul
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