From: dridi@choco.UUCP (Gilles Dridi ERF004)
Newsgroups: comp.sys.amiga.advocacy
Subject: Re: DSP & sound + expansion capability / Was: COMMODORE - HERE'S A CLUE
Date: 13 Oct 92 02:19:30 GMT
Organization: Not an Organization

In article <1992Oct8.152203.27725@murdoch.acc.Virginia.EDU> ccb8m@onyx.cs.Virginia.EDU (Charles C. Bundy) writes:
>grr@cbmvax.commodore.com (George Robbins) writes:
>
>>In article <1992Oct5.180757.1@cc.helsinki.fi> jalkio@cc.helsinki.fi writes:
>>> In article <OA92-901-306p1_88E8203B@piraya.bad.se>,
>>> Hans_Bergengren@p1.thulos.bbs.bad.se (Hans Bergengren) writes:
>>> >
>>> >  GR> Not even Atari was dumb enough to try and create a custom chip that
>>> >  GR> did 16-bit audio, the job is much better given to a DSP to handle.
>>> >
>>> > It's NOT! Suppose you want the DSP to do other stuff, like voice
>>> > recognition, image enhancing, or 3D graphics, or any other of that
>>> > nice stuff a DSP can do, why waste bandwidth on such a simple task
>>> > as outputting audio?
>>>
>>> Hey! As far as I have understood, the DSP is NOT needed for Audio output
>>> (even 16-bit stereo, or maybe 8-channels). There is a special
>>> audio-matrix-subsystem for that. You use the DSP, if you want some
>>> realtime audio processing.
>>
>>From the description of the "audio matrix" it sounds like some analog
>>multiplexing of the audio signals.  This suggests that you can combine
>>the DSP and the other on-board noisemakers in various clever ways, but
>>the DSP is probably the only on that can generate 16-bit audio.
>>
>>It could be something better, but don't assume that something nice sounding
>>like and audio-maxtrix-subsystem offers more than offered by the basic
>>on-board resources.
>>
>
>I have one simple question to this ongoing thread :)  How on earth can a
>DSP "generate" any kind of audio?  Does it have an ADC?  Your bit limit
>range on sound comes from the ADC not the 56K DSP in the falcon.  The
>statement "16 bit sound can only be generated by the DSP" doesn't make
>sense in this context (unless you have a bunch of resistors hanging
>off it:)
>
>For audio applications the DSP can be used to perform all kinds of neat
>filter/wave modification stuff in real-time, but it won't generate any
>kind of analog signal...
>
>DSP's can also be used as input noise/signal conditioners (if you have an
>ADC, in addition to a DAC) and I've seen numerous video processing/
>active vision projects using DSP's.  Neat stuff, and I can't wait until
>one becomes standard for the Amiga (sure I can wait, I waited for a minimum
>8 bitplanes, with a tightly coupled video subsystem :)
>
>Charles C. Bundy IV

    Thank you for this explanations about DSP & sound Charles.
    Do you know if the Motorola 56001 DSP has an expansion bus like the AT&T's?

    Sure, you can do a lot of processing with DSP and various too. Yet, what's
    suprising me more, it's the capability to plug modules (mainly ADC DAC) onto
    DSP port (which is in case of AT&T a reconfigurable serial line).
    For instance, a modem, an audio stuff.

    In fact, it would be nice to have built-in DSP into Amiga since it's can be
    another way to expand computer capabilities; other than ZorroIII bus in the
    Amiga. Besides, you can easily communicate with the extern module you design
    by the mean of the serial line.
    Perhaps a software device, DSP independant, should be realized for the Amiga
    so that you can sell cheap DSP with low-end machine and other powerfull ones
    for high-end part. But, it's dream and furthermore, I don't think Commodore
    to allow enough software engineers to work on the project.
    I'm "sure" the Atari's solution to provide cheap DSP freely programmable is
    more realistic.

    I'm waiting for cheap AmiGA. (What can I do other than to buy a $1400 486?)

--
Gilles Dridi
  o  o		      oo_
 <O\/O>  Mi Amigo    \OO>  Mi A....!
 /|  |\ 	      ||
email: cbmvax!cbmehq!cbmfra!choco!dridi