DSL-504T modem

We have a 6-7 year old DSL 504T modem. It functions OK when left alone but seems to be erratic when parameters are changed or configurations are uploaded. I am wondering if this could be flash/EEPROM fade - anyone had similar problems?

On a more general note, for how long can flash memory or EEPROMS reliably hold programming code or static data.

I have decided to replace the modem anyway as new ones are quite cheap.

 

It should hold the data "indefinitely". Technically there will be a
limt to how many times the chips can be written to (just as there is
with those fancy new solid state drives), but unless you're changing
the configuration multiple times a day, you should get anywhere near
that limit.

But it begs the question why you're changing it so often? Once set-up,
you shouldn't need to change the modem ... unless you're one of those
strnage people who changes internet providers more often than their
underwear.

 

Oooh, I had one of those a couple of modems ago. The ADSL stopped
working, but I kept it as a switch for a while.

Cheers,

Cliff

 

It should hold the data "indefinitely". Technically there will be a
limt to how many times the chips can be written to (just as there is
with those fancy new solid state drives), but unless you're changing
the configuration multiple times a day, you should get anywhere near
that limit.

But it begs the question why you're changing it so often? Once set-up,
you shouldn't need to change the modem ... unless you're one of those
strnage people who changes internet providers more often than their
underwear.

 

I changed it twice this year (password then to add something to DMZ) and did not touch it for the last three years. Cannot be that.

 

I change the wireless blacklist on mine often, in an attempt to limit how
much time my teenagers spend in bed glued to a screen. I'm sure there's
other use cases, too.

 

For EPROMs and EEPROMs I'm familiar with (in embedded systems
programming), the lowest specification I've seen mentioned for data
retention is 10 years. Some EEPROMs are rated to retain data for 100
years. These should be minimums, and assume the device is used within
its operating parameters - it could be a lot less if exposed to out of
range temperatures or voltages.

Flash memory is harder to pin down. The data book I happen to have handy
(from Atmel in 1998) doesn't mention data retention time for Flash. I
expect Flash is supposed to retain data for at least ten years, matching
EPROM.

They certainly don't last forever - the data is stored by holding
electrons in a memory cell (similar to a capacitor), and they gradually
leak electrons. Rewriting cells should give another full lifetime.

The other question is the number of rewrite cycles each cell/block in
the device is guaranteed to handle. The lowest I've seen is the
integrated program memory Flash in some CPUs, which was only rated for a
minimum of 100 write cycles. (When they ran out, the CPU wasn't much use
any more, which meant replacing the whole board if wasn't practical to
remove the CPU and solder on a new one.)

Most EEPROM and Flash memory I've worked with is rated for at least 1000
or 10 thousand cycles, and I've seen some which claim to support 100
thousand or 1 million write cycles.

(SSDs are more complex - I'm talking about simple memory chips here.)