oryoki2000 wrote:
> Walter Knapp wrote:
>
>>I was told that there is a small current circulating
>>in the memory to maintain [the data].
>
>
> Nope. Compactflash, Memory Stick, Smart Media, Secure Digital,
> and other modern flash memory formats are "non-volatile."
> They do not require power to maintain data. Search Google
> for "compactflash non volatile" for many references to
> manufacturers' pages describing how no power is required.
>
> You may be confusing this with SRAM (static RAM), which
> does require a tiny power source to maintain memory
> contents.=20
They store a charge, which can be changed by a stronger electric field.
Read for yourself.
That may explain why here in Georgia I know several folks who have lost
very hard to get photos stored on these things. All are field
biologists, but not sound recordists.
I've had components in computers vaporized by lightning bolts that never
hit the ground here. Cloud lightning. The voltages to do that were
induced in sometimes very short sections of wire or even circuit traces
and in spite of a elaborate surge suppression system. Flash memory
takes even less voltage to change it.
I don't remember any lightning exposure when I had problems with flash
memory not holding. But around here we hardly notice such stuff as it's
common. We only take precautions when it's close enough.
So, current technology in them has no battery. The required electrical
differential that's the actual memory is stored directly in the solid
state substrate.
Note that non-volatile includes hard disks, optical disks, minidiscs.
Walt
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