VIA board, was: Re: [sdiy] super cheap synthisizers

[Batz Goodfortune]

Y-ellow Theo 'n' all.

At 10:53 PM 6/13/02 +0200, Theo wrote:
>There are relatively cheap DSP evaluation boards available.
>Like the AD 21061 EZLITE from Analog Devices ($179  48khz 16bit stereo)
>Might be a better basis for a synth than a general PC board?

Yeah. I'd love to do that. But still that's 180 clams you could spend on 
something that gives you more bang for your buck. Unless you really really 
want to code a synth in DSP then it's probably the way to go.

Years ago I worked for a sound card company that was rapidly going defunct. 
The upper management were literally on drugs and I got ripped off badly but 
that's the story of my life. I recognized that the major advantage of a 
sound card chip is that it's all done in dedicated hardware. The processor 
only has to tell it what to do and when to do it. Whilst some of my 
colleagues were pushing the traditional scheme of multi-DSPs and a bulky 
Multi-DSP OS, I found myself reasoning this way.

Instead of a bunch of big bulky DSP chips all talking to each other, why 
not design a chip where there are (at the time) 24 little dedicated DSP 
like structures. Each placed between the resource access logic and the 
channel mux/interpolator. Each one couldn't do a whole hill of beans and 
would have to be optimized for performing audio tasks but that's the beauty 
of the system. Each one would be mean and lean capable of one synth 
channel. Each one would be relatively independent of each other and 
therefore guarantying 24 channels no matter what. Each one could be running 
a different kind of synthesis at any given time. And further, each one 
could be assigned it's synthesis method on the fly in the same way that 
dynamic assignment works. Giving all the efficiency of a totally hardware 
based synth.

My colleagues ran with the idea for a while and we decided that it would 
probably make better sense to do them in 8 channel chunks and have them 
mounted to something a-kin to a 30 pin SIMM. (As DonTronics is doing with 
their SIMM stick processor thingies now.) That way we could offer solutions 
to the synth makers in general and reign in some development costs. This 
was mainly the province of the bean counters but it made sense to me. 
Ironically the software team were developing a system to go with this which 
was so similar to MP4 it's not funny. And this was before MP3 was even the 
rage. And whilst the MP4 community is struggling with ways to implement it, 
we already worked that out.  But I digress.

I've largely kept this a secret until now because I was clinging to the 
hope that one day I might be able to see this happen but what the hell. I'm 
never going to be in that position so it may as well be out there. And 
besides there are probably even better ways these days. We were even 
starting to investigate  using embedded xilinx or altera type technology. 
You could then not only re-program the DSP software but the DSP hardware on 
the fly as well. And I know all this is doable because a computer scientist 
friend of mine was developing algorithmic systems for xilinx to do just 
this kind of thing. And she was saying that you can reprogram major chunks 
of xilinx chips in nano seconds these days.

Err but yea. But the reason I'm mentioning this is that the problem with 
DSPs we found, (And you'll note this with things like the Nerd Bleed and 
the Creamware Pulsar etc) is that you tend to waste half your DSP power (Or 
there abouts) getting the damn things to co-operate. We had a company 
working for us that specialized in multi-DSP Operating systems and even 
they couldn't get the efficiency down below a certain point. The more DSPs 
you add the more overhead you create. You've either got to have one 
gee-fucking-wiz DSP or run the gauntlet of trying to get them all to behave 
together. Or settle for something like 6 DSP56Ks but each one produces one 
voice only.

At least with the Nerd Bleed and nodular, they put some limitations in 
place but the Pulsar, and it's SHARC farm, it just goes till it runs out of 
steam and then becomes unpredictable. And it can suffer the peak load 
problem where a sudden burst of overhead is required at the deficit of 
other things that may be going on at the time. I guess it's not properly 
load balanced but there goes a chunk of your processing power right there.

If I must work with DSPs these days, I'd be looking for either some 
cheap-shit old DSP hardware for nix to mess with or whack a bunch of old 
DSP56Ks on a proto-board or something. But life is short and I'm having Oh 
so much fun practicing to be a zombie.

You could perhaps look for one of those old Total Bitch, err I mean Turtle 
Beach DSP56K cards they had. The original MouldySound cards. People use to 
be able to do all kinds a stuff with them.

Hey Paul P? You got any of those DSP synth boards left your mate designed?

Be absolutely Icebox.

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