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Re: More Thoughts on Green Arrays

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rickman <gnuarm@gmail.com> writes:
>> Doing 8 bit operations seems to cost a big slowdown for shifting and
>> masking, if you want to use the on-cpu ram to hold 2 bytes per word.
> "Seems"?  I don't see how it is that much of a hindrance to work with
> bytes, but you know your apps.

I was thinking about the RC4 stream cipher.  On a conventional processor
including a typical 8 bit micro, each byte of output takes around a
dozen instructions, juggling around a 256 byte memory array.  On the GA,
I haven't counted exactly, but it's quite a bit more arithmetic and you
end up using three nodes.  Despite this, I think RC4 on the GA is
reasonably practical.  An RC4 key cracker might be an interesting GA144
application if you want to attack password-protected files from old
versions of Microsoft Word or a few other such programs.

> Again, I'll take your word for it.  Most DSP devices are 16 bits and
> the top end 32 bit devices use Watts rather than milliWatts.  I just
> don't see how 144 processors would be slow doing 32 bit arithmetic.

Well, look at the md5 notes, they split 32-bit words into 16-bit halves
stored on separate nodes, then have to juggle the halves around,
propagate carry bits between nodes, etc.  The GA144 running flat out
uses about 0.6W.  You get a stupendous amount of mips for that power,
but it's not something you can run from a watch battery.

> Yes, external memory doesn't run at 2 ns.  But does that mean it is
> too slow for a given app?  If your apps only run on processors which
> have 2 ns access to tons of memory, then yes, these chips won't do the job.

Yes, the caches in a conventional x86 or fast ARM processor are 2ns and
quite large compared with the GA144 memory.

> I think software defined radio is one area where this chip will
> shine!  You don't need tons of memory for that, you need fast
> processing. 

That's interesting and I'm glad to hear it.  You probably know a lot
more about SDR than I do.  But, I think I calculated that the GA beats
just about everything for energy per integer addition, it's not really
far ahead of dedicated DSP's for MAC, and might have been behind some.
I posted numbers in an earlier newsgroup message but no longer remember
them.

>> Yes, possibly so, I'm used to processing big piles of character data
>> so for me it keeps coming back to byte operations 32-bit math, but I'm
>> sure there's lots that I'm not thinking of.
>
> What types of apps are these?

The usual data communications and crypto stuff, character processing, etc.  
Data compression wants a lot of memory besides the computation.

>> If you have any example application ideas you can reveal...
> I still don't know enough about them to know what I can and can't do
> with them.  I may need to spend some time with the MD5 app note.  It
> looks like that is the one with the most info at the moment.

Cool.

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More Thoughts on Green Arrays rickman <gnuarm@gmail.com> - 2011-04-09 10:44 -0700
  Re: More Thoughts on Green Arrays "Greg Bailey" <greg@GreenArrayChips.com> - 2011-04-09 17:53 -0700
    Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-04-10 14:53 -0700
      Re: More Thoughts on Green Arrays "Greg Bailey" <greg@greenarraychips.com> - 2011-04-11 10:18 -0700
  Re: More Thoughts on Green Arrays Brad <hwfwguy@gmail.com> - 2011-04-11 14:44 -0700
    Re: More Thoughts on Green Arrays Brad <hwfwguy@gmail.com> - 2011-04-11 17:11 -0700
      Re: More Thoughts on Green Arrays rickman <gnuarm@gmail.com> - 2011-04-11 21:41 -0700
        Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-04-12 00:06 -0700
          Re: More Thoughts on Green Arrays rickman <gnuarm@gmail.com> - 2011-04-12 06:22 -0700
            Re: More Thoughts on Green Arrays Charley Shattuck <cshattuck@surewest.net> - 2011-04-17 21:11 +0000
              Re: More Thoughts on Green Arrays rickman <gnuarm@gmail.com> - 2011-04-17 14:53 -0700
              Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-04-19 21:13 -0700
                Re: More Thoughts on Green Arrays Albert van der Horst <albert@spenarnc.xs4all.nl> - 2011-04-20 17:42 +0000
                Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-04-23 04:03 -0700
                Re: More Thoughts on Green Arrays foxchip <fox@ultratechnology.com> - 2011-04-23 23:10 -0700
                Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-04-25 09:00 -0700
                Re: More Thoughts on Green Arrays rickman <gnuarm@gmail.com> - 2011-04-25 17:10 -0700
                Re: More Thoughts on Green Arrays foxchip <fox@ultratechnology.com> - 2011-05-01 10:37 -0700
                Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-05-02 00:14 -0700
                Re: More Thoughts on Green Arrays foxchip <fox@ultratechnology.com> - 2011-05-02 08:20 -0700
                Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-05-03 21:26 -0700
                Re: More Thoughts on Green Arrays "Greg Bailey" <greg@greenarraychips.com> - 2011-05-07 20:11 -0700
                Re: More Thoughts on Green Arrays "Greg Bailey" <greg@greenarraychips.com> - 2011-05-08 22:35 -0700
                Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-05-09 08:11 -0700
                Re: More Thoughts on Green Arrays Albert van der Horst <albert@spenarnc.xs4all.nl> - 2011-04-26 11:22 +0000
                Re: More Thoughts on Green Arrays foxchip <fox@ultratechnology.com> - 2011-05-01 10:05 -0700
                Re: More Thoughts on Green Arrays Albert van der Horst <albert@spenarnc.xs4all.nl> - 2011-05-02 12:01 +0000
                Re: More Thoughts on Green Arrays foxchip <fox@ultratechnology.com> - 2011-05-02 07:51 -0700
                Re: More Thoughts on Green Arrays "Greg Bailey" <greg@greenarraychips.com> - 2011-05-08 22:23 -0700
              Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-04-27 23:17 -0700
            Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-04-17 20:41 -0700
              Re: More Thoughts on Green Arrays rickman <gnuarm@gmail.com> - 2011-04-18 21:38 -0700
                Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-04-19 22:20 -0700
                Re: More Thoughts on Green Arrays rickman <gnuarm@gmail.com> - 2011-04-20 00:56 -0700
                Re: More Thoughts on Green Arrays Paul Rubin <no.email@nospam.invalid> - 2011-04-20 23:02 -0700
                Re: More Thoughts on Green Arrays rickman <gnuarm@gmail.com> - 2011-04-22 10:32 -0700
                Re: More Thoughts on Green Arrays Bernd Paysan <bernd.paysan@gmx.de> - 2011-04-22 22:06 +0200
                Re: More Thoughts on Green Arrays rickman <gnuarm@gmail.com> - 2011-04-23 18:42 -0700
                Re: More Thoughts on Green Arrays "Paul E. Bennett" <Paul_E.Bennett@topmail.co.uk> - 2011-04-23 12:17 +0100
          Re: More Thoughts on Green Arrays Albert van der Horst <albert@spenarnc.xs4all.nl> - 2011-04-26 11:03 +0000

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