On January 17, 2007 08:55 am, Christopher Friedt wrote:
> Hi James,
>
> Neither of these boards will execute any code from flash as opposed to
> ram, that would hinder the processor drastically. I don't even think the
> processor supports program addressing in flash-based devices.
Technically NOR flash can execute code in-place (XIP). See article:
http://www.edn.com/article-partner/CA6257144.html
Nand Flash cannot XIP. It works more like a hard drive loading and storing
sectors. Nand also need to correct errors that occur in each pages(ECC), NOR
doesn't.
I'm not sure if the TS-7200 with NOR flash uses XIP. But that should not
really matter. The EP9302 (or EP9301 on earlier TS-7200 boards) has enough
cache to store most of your critical code. Its the speed of the cache that
will be the biggest factor.
So Nor and Nand will only make a difference in the speed of loading code to
your cache. Once the code is in the cache it will go at top speed!
>
> You're looking at nearly the exact same execution time. There would only
> be a very slight difference if one board had 32 MB sdram and one had 64
> MB sdram, since a board w/ 64 MB sdram has a dis-contiguous ram layout
> and thus would require a very very slight overhead in page table
> translation from virtual addressing -> physical addressing.
The 32MB sdram is discontinuous too. The EP9302 stores data and code in the
cache indexed by its virtual address, not its physical addresses. So once the
code is in the cache it does not need address translation to get fetched
again. So address translation will not slow it down.
>
> ~/Chris
>
> twhk2007 wrote:
> > Hello all !
> >
> > TS-7200 uses NOR flash while TS-7260 uses NAND flash. I know that the
> > read time for NOR flash is faster than that of NAND flash. I will use
> > the board to do a lot of floating point calculations. Could you anyone
You may look into downloading the Cirrus Logic GCC compiler with Maverick
Crunch enabled. This could double the speed of your code. The only problem is
the TS Linux kernel does not support Maverick Crunch. So it isn't initialized
and you can't have more than one task using it, as the Crunch registers are
not preserved between tasks. You will also have trouble linking to libraries
that were not compiled with it.
Some people have ported Linux 2.6 kernels that should support Crunch.
-Curtis.
> > on the execution speed for these two boards ? Some people mention that
> > the code in NAND flash will be transfered to SDRAM during excution, so
> > the excution speed of a NAND flash-based board can be faster than NOR
> > flash-based board. Is this true for TS-7260 ?
> >
> > Best regards,
> > James
> >
> >
>
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