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<p>Wojtek,</p>
Yes for me the focus is the special hardware not the
micro-controller. Let me try to explain for what I insist at point.
In advance, I do not try to "evangelize" anyone.<br>
<br>
Unfortunately or fortunately, only a point of view ;), I come from
hardware, from FPGA hardware even worst from industrial FPGA
hardware, game rules are different.<br>
<br>
To use a 28 USD chip I need justify that this chip provide the best
solution. A basic rule in industry is : a project use FPGA because
is the only practical solution if not use a micro-controller.<br>
<p>In this context chose a bigger component adding 6.44 USD to the
costs when an external 50MHz ARM cost around 3.5 USD could be hard
to justify. Beside the cost of a chip is the development cost that
in case of ARM is significantly lower because it is a better know
component than an FPGA.</p>
<p>Combined this cost with Paul numbers I could conclude that in the
case of DSP blocks for multiplication add 6.44 USD to the cost of
each unit optimize only 0.15% of the software. <span
class="tlid-translation translation"><span title="" class="">A
conclusion drawn from the hairs</span></span> I agree but
illustrate the type of analysis that we need do.<br>
</p>
<p><span class="tlid-translation translation"><span title=""
class="">I insist because I would like to see a growing
community but for that</span></span> it has to fit into the
industry and play by it rules.</p>
<p>Regards,</p>
<p>Walter<br>
</p>
<br>
<div class="moz-cite-prefix">El 17/2/19 a las 01:17, Skulski,
Wojciech escribió:<br>
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<blockquote type="cite"
cite="mid:CY1PR07MB263470036B698B084F28D4E8FF620@CY1PR07MB2634.namprd07.prod.outlook.com">
<pre class="moz-quote-pre" wrap="">Walter:
Walter Gallegos [<a class="moz-txt-link-abbreviated" href="mailto:waltergallegos@vera.com.uy">waltergallegos@vera.com.uy</a>] said:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Implementing a general propose microprocessor system alone
in FPGA is impractical beyond the research or ASIC prototypes.
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">
I agree, but... The motivation for RISC5 was that Oberon System software was available. The traditional rules of computer design have been turned upside down. Traditionally, the CPU is designed first, and compilers and other software are then developed to support the CPU. Here it was just the opposite. The operating system existed. The CPU was then designed to run the software, not the other way around. This course of actions seems pretty unique to me.
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<pre class="moz-quote-pre" wrap="">For industrial applications the microprocessor must coexist
with some special hardware that justifies the use of FPGA.
</pre>
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<pre class="moz-quote-pre" wrap="">
A very good point. But it can be turned upside down too. The "special hardware" can be termed a "coprocessor" for the microprocessor. It depends what is more important to you. The Oberon programmers will probably put the RISC5 and its software in the foreground. They will probably say that the "special hardware" is bunch of registers plus some obscure logic delivering the content to these registers. Your point of view may be the opposite. To you, the "special hardware" is the focus, while the CPU is a necessary devil to set it up and to monitor its operation.
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<pre class="moz-quote-pre" wrap="">In this environment, wasting DSP blocks
could be a not recommended technique.
</pre>
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<pre class="moz-quote-pre" wrap="">
If you say "wasting", it means that you need them for something else. Then you are presumably building a coprocessor ("special hardware") where you need these blocks. This in turn implies that you are designing in a resource starved environment and you need to compromise either the CPU or the "special hardware" because there are not enough DSP blocks for both. If so, then I would ask: why not choose a slightly larger FPGA with more DSP blocks?
Let me give an example of a particular Artix FPGA and the next higher Artix in the same FT256 footprint. I took the price from DigiKey.
XC7A15T-1FTG256C $27.93 45 DSP blocks
XC7A35T-1FTG256C $34.37 90 DSP blocks
Thanks,
Wojtek
--
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<a class="moz-txt-link-freetext" href="https://lists.inf.ethz.ch/mailman/listinfo/oberon">https://lists.inf.ethz.ch/mailman/listinfo/oberon</a>
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