Re: Does reboot clear RAM?

[Joachim Durchholz]

Am 12.11.19 um 02:20 schrieb Jakob Bohm:
> On 11/11/2019 20:27, Joachim Durchholz wrote:
> > Am 11.11.19 um 15:35 schrieb Jakob Bohm:
> > > On physical machines, the following mechanisms are common:
> > >
> > > 1. DRAM chips physically loose their contents after a few seconds of 
> > > power
> > >    off,
> >
> > I am by no way an expert, but the forensic experts tell me that data 
> > can persist for *minutes*.
> > Of course, the first bits flip after a few seconds. But you don't get 
> > a guarantee that everything is zeroed.
> > I also hear that temperature plays a really big role here.
> There's a difference between reading faded bits with special analogue 
> equipment
> after artificially cooling chips way below what the datasheet allows, and
> reading the digital bits at normal temperature, voltage etc.

The refresh circuitry of a DRAM chip is just for the purpose of reading 
faded bits.
And of course it will read whatever it decides is in the cell. If enough 
electrons are left, it will be above the threshold, so you can expect to 
see the occasional 1 bit in RAM unless it's cleared.

I'm still interested in hearing whether typical RAM has a RST line and 
whether that wipes memory (or merely initializes internal circuitry).
Speculation about potential low-level circuit trickery is nice but does 
not answer that question, I fear.

Regards,
Jo