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SubjectRe: Encrypted Swap
On Fri, 17 Aug 2001, Holger Lubitz wrote:

> "Richard B. Johnson" proclaimed:
>
> > Errrm no. All BIOS that anybody would use write all memory found when
> > initializing the SDRAM controller. They need to because nothing,
> > refresh, precharge, (or if you've got it, parity/crc) will work
> > until every cell is exercised. A "warm-boot" is different. However,
> > if you hit the reset or the power switch, nothing in RAM survives.
>
> Then this may have changed with SDRAM. However, back in my Amiga days it
> was pretty common to just reset the machine and rip whatever was left in
> the memory (DRAM). If memory serves me right, some people put in reset
> protection (by pointing the reset vector to some code that cleared the
> memory), which could be fooled by hardware reset or power cycling.
>
> Holger

Yes, even in the early PC-XT and PC/AT, where the DMA controller was
used for refresh, it was quite possible to reset the machine and
have RAM contents (except for the first 1 megabyte) remain untouched.
The first 1 megabyte was cleared, actually the first 640k, because
the boot code depended upon this. It didn't clear RAM used for
temporary variables.

But, now-days, you can't reset the machine without killing whatever
is in RAM.


Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).

I was going to compile a list of innovations that could be
attributed to Microsoft. Once I realized that Ctrl-Alt-Del
was handled in the BIOS, I found that there aren't any.


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