Re: [NTLK] Flash card power usage & stuff

On 8/24/2009 10:49 AM, Bob Carls Dudney wrote:
> On 23/8/09, M. Horvat wrote:
> |
>> flash [cards] reduce wear on interal flash chip
>
> Even with heavy use, internal flash should last many years even if
> its your main or only store. But once it's gone your machine probably
> is, too. And without external flash there's no backup. Also, one
> needs at least one additional flash card to backup external card(s)
> (assuming one has more on card than free memory on internal; if not
> one could use internal store for backup, but it generally won't last
> as long as an external flash backup because some operations
> exclusively write to internal store, e.g, owner and work site cards,
> system preferences).
>
While this is true, you can really reduce the amount your internal flash
is used by saving most data to cards. Certainly data that changes. If
you use this method, then the only data that is changed on the internal
is alarms and preferences (system soup). Since the Newton has very good
quality flash memory installed internally and as I understanding it,
wear leveling as well. Then it is quite possible that your newton
memory will out last you.

I use a alarm system that stores them externally rather than internally
to save a few write cycles as well.

>> Newton-compatible [linear] cards increasingly rare
>
> Tima Scientific in Toronto lists many. Yes, they are a lot more
> expensive than ATA. One can do better on eBay and also on this list
> occasionally.
>
>> 2. Do flash cards use any extra power when they are not read or written to?
>
> The best cards sleep when not being accessed, a state that only draws
> a few mA if any. My inexpert observations of amp readings suggest
> cards suck no more than a few mA when awake and idle, so the sleep
> function is probably negligible benefit. (They also seem to go to
> sleep in less than a minute.)
>
> Far more significant to battery drain is how much Newt is on.

Sleep is a relative term. Generally storage cards don't take energy not
being accessed, unless they are SRAM. But the battery usage of SRAM is
so small you will unlikely notice it. Also it should be mentioned that
flash cards take very low power at access, but when writing data energy
required is far far greater. SRAM of course is the exception since the
energy requirements is constant (and very low).

>
>> 3. How about heap?
>
> Since no one else is responding: my inexpert understanding is soups
> and non-frozen packages are the main consumers of heap, not the card
> itself. I've certainly never noticed a difference whether using
> internal or external store.

Soups do not consume heap per se (certainly not on a constant basis and
depending on usage), put unfrozen packages definitely do. Also the card
itself DOES in fact take heap. The larger the card the more heap it
will take as the Newton has to keep track of memory on the card. There
is not a difference internal VS external, unless you are using a
fragmented card/store then you will definitely see a difference in
speed. Or you are using a ATA driver with a ATA flash card, that will
be slower.

If you wish to test the larger card vs smaller card. Take a small
capacity and a large capacity card (both empty). Insert them into a
newt and take notice of the heap. You will see a difference. Granted
in general it is not worth being concerned about with a MP2x00 but with
130 or earlier and certain applications that need every bit of heap you
can get....it does.

-Dan

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Received on Mon Aug 24 20:23:17 2009