🚀 go-pugleaf

rnichols@cbnewsg.cb.att.com (robert.k.nichols) writes:
> In article <1992Dec27.105039.25690@microsoft.com> chuckst@microsoft.com (Chuck Strouss) writes:
> ...
> >It is surprising how long some DRAMs can go without refresh.  For
> >production systems, you must believe the manufacturers worst-case
> >specs, but DRAMs rarely need to be refreshed that often.
> ...
> 
> The length of time that a DRAM cell can hold its content without
> refresh is inversely proportional to the leakage current in the
> device.  The leakage current, in turn, is an *exponential* function of
> temperature.  What this boils down to is that a device with cells that
> must be refreshed every 2 ms at max rated temperature will hold
> information for over 20 SECONDS at a junction temperature of 25 C.
> One particularly nasty consequence of this is that it becomes very
> difficult to tell whether refresh is working correctly in your system,
> and even harder to devise a test which will reliably detect memory
> cells that might be marginal (from a refresh standpoint) at high
> temperatures.
Correct, but it was a simple question and I wanted to give a simple
answer. I know that DRAMs can do it without refresh for seconds at
room temperature, but it's really not advisable for a greenhorn to
try it...
BTW, I wrote a program that switches to lower refresh rates whenever
possible (some PCs fail to access diskettes if the rate has been
changed, and the beep won't work correctly). If anyone is interested
in it, please email.

Happy new year!

Chris
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Christian Blum                   Universitaet des Saarlandes, Germany
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