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Old 01-07-2004, 08:52 PM
Yttrium
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Default newbie question: speed grade + area constraint

this might be a stupid question, but what does a speedgrade actually mean? i
haven't found a clear and short answer yet! and the second question (might
again be a stupid question) what does:

Found area constraint ratio of 100 (+ 5) on block uart_controller, actual
ratio is 1.

mean? i have got this after compiling and what does the 100, +5 and 1
exactly mean?

thanx in advance,

greetz

Yttrium


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Old 01-07-2004, 10:50 PM
Peter Alfke
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Default Re: newbie question: speed grade + area constraint

Speed grade is the manufacturer's way of testing and classifying the
parts according to their actual speed. Memories have done that for decades.
So the only difference between different speed grades of the same
device type is that some are faster than others. And Marketing sets the
prices accordingly, so the faster parts are sold for a higher price. No
other differences.
All ( i.e. each individual) Xilinx FPGAs are tested 100% for speed while
operating at their highest guaranteed temperature. And testing means
reconfiguring hundreds of times, and running millions of test vectors
through each part.
"We really sell used FPGAs" :-)
I would imagine that our competitors do the same. It's the smart thing
to do...
Peter Alfke

Yttrium wrote:
>
> this might be a stupid question, but what does a speedgrade actually mean? i
> haven't found a clear and short answer yet! and the second question (might
> again be a stupid question) what does:
>
> Found area constraint ratio of 100 (+ 5) on block uart_controller, actual
> ratio is 1.
>
> mean? i have got this after compiling and what does the 100, +5 and 1
> exactly mean?
>
> thanx in advance,
>
> greetz
>
> Yttrium

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