[sdiy] Digital delay memory

Eric Brombaugh ebrombaugh1 at cox.net
Wed Apr 27 20:07:24 CEST 2016

On 04/27/2016 10:57 AM, Richie Burnett wrote:
> Although one is supposed to refresh every location of DRAM at least
> every 16ms, I was once amazed to find intelligible audio playing out of
> the chips after I'd hit a breakpoint in the debugger and the refresh had
> be stopped for a couple of minutes!

That's true - DRAM data becomes unreliable if not refreshed but it 
certainly doesn't decay away to nothing. I remember "the good old days" 
when cycling power on a DRAM-based video card would still leave 
recognizable data visible on power-up.

The rate of data corruption is related to temperature - there are known 
computer security issues where hackers load up a machine's memory with 
secrets, cool the RAM with freeze-spray and then cut the power. 
Rebooting with a compromised OS then allows dumping the contents of the 
RAM for analysis without the victim OS and applications being able to 
detect the intrusion.


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