How do mains powered devices retain their settings when powered off

londonTiger

I know that motherboards in computers have a penny shape battery that keeps the cmos settings and time in memory, but what about routers, modems dongles etc, how do they retain the APN/SSID/port forwarding settings in their memory? I took a few apart and didn't notice any batteries in them.

Do they store the memory on a solid state like storage cell on the circuit board? if so how much data can they typically store and how long can they store the data?

I'd like to know because my business supplies 4g routers to businesses for use in conferences. We had 1 model with 2 sim card slots and we set the device to switch sims after 95% of the sim cards data capacity is used. Auto sim switching doesn't work because the network still serves web pages (the top up notification page) and the router does not detect that the sim has ran out of data.

The router keeps a count of the data used, but I don't know how long or how accurately it will retain the data.

TadleyBaggie

Non-volatile RAM. Access to such is quite slow compared to normal RAM, which is why it generally only used to hold small amounts of configuration data.

londonTiger

TadleyBaggie wrote: »

Non-volatile RAM. Access to such is quite slow compared to normal RAM, which is why it generally only used to hold small amounts of configuration data.

and I presume this data will be permanently held until rewritten over?

I_have_spoken

EEPROM

RobertoMoir

londonTiger wrote: »

and I presume this data will be permanently held until rewritten over?

Near as makes no odds, yes.

enfield_freddy

pixies ,,,, lots of them

esuhl

Non-volatile memory:
https://en.wikipedia.org/wiki/Non-volatile_memory

enfield_freddy wrote: »

pixies ,,,, lots of them

I thought they were what made my monitor glow... :-/

enfield_freddy

no ,,,, that is fairies , easily mistaken , but pixies have better memories , that's why they are used


the bloke that's sat in your printer with crayons is the clever one

J_B

enfield_freddy wrote: »

the bloke that's sat in your printer with crayons is the clever one

:rotfl:


:beer:


ten characters

prowla

The wee chappie who paints the picture in a camera when you press the button is really quick.

Peter999_2

Always seems to run out of pink though.