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From: John H Meyers on 5 Feb 2010 07:27
On Fri, 05 Feb 2010 03:50:01 -0600, val wrote:

> I bought a TDS 1Mb RAM card last summer and the programs are still
> in the card even if the card was removed from the HP for more than
> 3 months. However, there is no battery holder on the card
> so I guess it is flash memory (?). There is no switch as well.

The battery is sealed into the card.

Remember when PCs had CMOS batteries soldered onto their motherboards?

What happened when those batteries ran down and could not recharge?

[r->] [OFF]
From: val on 5 Feb 2010 10:42
John H Meyers a �crit le 05/02/2010 :
> On Fri, 05 Feb 2010 03:50:01 -0600, val wrote:
>
>> I bought a TDS 1Mb RAM card last summer and the programs are still
>> in the card even if the card was removed from the HP for more than
>> 3 months. However, there is no battery holder on the card
>> so I guess it is flash memory (?). There is no switch as well.
>
> The battery is sealed into the card.

Ah, OK !

>
> Remember when PCs had CMOS batteries soldered onto their motherboards?
>
> What happened when those batteries ran down and could not recharge?
>
> [r->] [OFF]

Bad things ?


From: Ingo Thies on 10 Feb 2010 11:31
John H Meyers wrote:

> The original HP49G is the oldest of this series having flash memory
> for "ROM" and for "Port 2." Subsequent models have a different
> architecture, and probably different flash chips as well.

The original posting addressed a Casio 5800P, not a HP calculator,
which, in addition, also use battery-suspended RAM, and do write/erase
the Flash memory only if the user intends to do so. The Casio 5800P
seems to write the memory content (or just the recent changes?) to the
Flash each time it is switched off, at least if I am understanding the
manual correctly.

The Flash wearing problem with HPs can in principle be circumvented by
using SD cards, which can be used with, e.g., the HP 50g. They are also
Flashes, of course, but could be replaced without replacing the whole
calculator ;-)

Ingo
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