Re: Long term reliability problems?
I have a couple of those Ramtron devices for some homebrew stuff I'm doing. They're great --- absurdly easy to interface to and utterly reliable. I'm using SPI/I2C parts, and they speak the same protocol that serial flash and SRAM do, except simplified not to need erasure before rewriting. Could not be easier to use.
Weren't expensive, either, although I got the impression that Cypress (who own Ramtron) aren't really set up for people wanting to buy less than a thousand or so. (I got two. In a very large box.) Here's a datasheet:
I do notice that they don't seem to have the parts in DIP8 any more, which is a shame is it's vastly more homebrew-friendly.
Also of interest is that you can get MSP430 microcontrollers with FRAM instead of SRAM. Which means, of course, that they can power down completely and restart with all their RAM intact. Again, not DIP, but it's still awesome.