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Do the chips really loose their programming after 40yrs?

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Triode

Active Member
I'm just curious about this because a lot of my PIC chips say in the datasheet that they hold their programming for 40 years. Don't get me wrong, thats long enough, I'm sure anything I make will be forgoten or broken in another way by 2050 anyhow. But I can't find anything that goes into more detail about this and im curious. Do they really loose their programming? What is the main cause of it? Are their chips that boast extended program retention?
 

Triode

Active Member
Yeah, I kind of figured it was just their way of saying that these chips don't last forever. I still wonder if there are special chips that are supposed to last longer. Not that I need it myself.
 

Triode

Active Member
I actually have one of those, a chip with a window, I got it out of an old power box. I dont know exactly what the box did but it was a big grey metal box with a really high capacity lever switch on the side and a circuit board in the back. I've never tried to program it cause I have no idea how, but it has a little window where you can see the chip inside, initially there was a foil sticker covering it.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I actually have one of those, a chip with a window, I got it out of an old power box. I dont know exactly what the box did but it was a big grey metal box with a really high capacity lever switch on the side and a circuit board in the back. I've never tried to program it cause I have no idea how, but it has a little window where you can see the chip inside, initially there was a foil sticker covering it.

Most probalby it's just an EPROM, and not a processor - the foil sticker was to keep UV out and prevent it getting erased.
 

Triode

Active Member
I did look it up using the code number, I just cant remember what it was now. It probably was just memory like you said. I read the datasheet because I was so curious as to why it had a window, it mentioned about sheilding it because a few hours of UV would erase it. I got a lot of parts from those because they were all in sockets where I could just pull them out. It was a big pile of them too. But almost all the chips were single and quad comparators, I pulled that stuff before Id really learned anything about electronics, so now Ive got a large jarfull of iffy quad comparators, and 2 or 3 larger chips.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I did look it up using the code number, I just cant remember what it was now. It probably was just memory like you said. I read the datasheet because I was so curious as to why it had a window, it mentioned about sheilding it because a few hours of UV would erase it. I got a lot of parts from those because they were all in sockets where I could just pull them out. It was a big pile of them too. But almost all the chips were single and quad comparators, I pulled that stuff before Id really learned anything about electronics, so now Ive got a large jarfull of iffy quad comparators, and 2 or 3 larger chips.

If I remember correctly?, they were numbers like 2708, 2716 etc.

Commonly they were used to store the operating system for microprocessors, and for larger systems enough to start the system and boot from floppy disk.
 

Sceadwian

Banned
eeproms and flash memory are basically the same thing just slight variations on a theme. The information is actually stored inside a capacitor in the chip. With chip sizes getting ever lower the insulation rating around these capacitors gets lower so leakage current increases which causes a shorter lifespan because even not connected to anything, just the tiniest little bit of current is leaking on. I doubt it's ever really an issue, but many modern micros have the ability to write to their own program memory so in theory if you had an RTC clock you could write code that could make the chip refresh it's own contents every so many years if you're on the paranoid side.
 

Triode

Active Member
In the same vein, If you really needed an electronic device to last 100 years, you could put in a couple chips with the same programming, with some kind of query they could run on eachother to make sure it was still programmed right, and if not it could reprogram that chip. But I cant think of many reasons you would need to do that.
 
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smanches

New Member
RAID 5 eproms? Thats an interesting idea.
 

Sceadwian

Banned
And virtually totally impractical, the cost/benefit ratio is almost 0
 

Triode

Active Member
That depends on how important it is. A bolt can be worth $7000 if it would be absolutely catastrophic if it failed.
 

bryan

Member
I'm just curious about this because a lot of my PIC chips say in the datasheet that they hold their programming for 40 years. Don't get me wrong, thats long enough, I'm sure anything I make will be forgoten or broken in another way by 2050 anyhow.

I bet that could be an issue with satellites. But suspect that is a whole different ball game with cosmic rays wreaking havoc on electrical components.
 
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