Seeking local source for thin-client IDE flash modules.

[Lennart Sorensen]

On Fri, Dec 05, 2008 at 05:27:00PM -0500, D. Hugh Redelmeier wrote:
> Shouldn't the one with the opposite connector come from
> subractonics.com?

Yeah maybe.

> Maybe that's a good alternate name for DealExtreme.com.  They have a
> lot of inexpensive stuff.  Mailed from Hong Kong (can easily take two
> weeks). Uneven quality.  Fun!
> 
> http://www.dealextreme.com/details.dx/sku.2720
> 
> This says nothing about DMA.
> 
> One comment suggest that this one is built better:
> http://www.dealextreme.com/details.dx/sku.00711
> 
> A comment claims slow transfers with this, but a reply points out that
> "no processing is performed by the adapter".
> 
> What is needed for DMA?  Is it at all a function of the adaptor?  DX
> makes a point of mentioning it in describing this adaptor (which isn't
> the right gender anyway):
>  http://www.dealextreme.com/details.dx/sku.9304

DMA requires that the DMA request and ack pins are connected from the
ide port to the CF card.  On older CF specs, the pins were reserved but
on newer spec cards the two pins are now DMA control.

If you use a card with DMA on a controller with DMA support using an
adapter without DMA support, you will get a lot of problems since they
will negotiate to use DMA and then fail to do so (with lots of DMA
timeout errors from the kernel).  One would have to boot with ide=nodma
to avoid the problem but also get much lower performance.

> DX also has SD to IDE adaptors.  That is a less-trivial operation and
> so they are more expensive.  I imagine that a fast SD is slower than a
> fast CF.  SD is a lot cheaper than CF.

Sure.  SD is a high speed serial interface.  CF is IDE.

> I happened to throw in these with my last DX order but haven't even
> opened the wrapper on them.  So I don't know if they are any good:
>  http://www.dealextreme.com/details.dx/sku.00711
>  http://www.dealextreme.com/details.dx/sku.2720
> 
> The silk-screening on 711 mentions DMA.

Always good.  All it requires is the two traces to be connected so there
is no reason not to do it.

-- 
Len Sorensen
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