Utility to test IDE cable connections?

"Michael Salem" wrote in message
T...
Some errors that are not noticed will have no consequences (corruption
of a bit in memory that is not used before it it next written to -- I
would expect this to be by far the most common case).

Alex Fraser wrote

Isn't expecting that "by far the most common case" is that a flipped bit is
written to before it is next read equivalent to saying that most bits are
written multiple times without being read inbetween?

Hmm. Maybe I just worked out the answer: processor caches result in exactly
that effect on main memory.

The experiment I propose would test this, speculation won't. The test
could be made with cache enabled and disabled, if possible.

The only matter of speculation here is over the odds
in a game of Russian roulette.

-- Bob Day

"Michael Salem" wrote in message
T...
Alex Fraser wrote
Isn't expecting that "by far the most common case" is that a flipped
bit is written to before it is next read equivalent to saying that most
bits are written multiple times without being read inbetween?

Hmm. Maybe I just worked out the answer: processor caches result in
exactly that effect on main memory.

The experiment I propose would test this, speculation won't. The test
could be made with cache enabled and disabled, if possible.

****, what is it with people evading my questions, using them as an excuse
to repeat themselves?

Your experiment is an excellent idea. Sadly, I wouldn't know where to start
to implement it. Well, almost, anyway. Probably the most accessible method
would be to do it in the Linux kernel.

Alex

Alex Fraser wrote:
"Michael Salem" wrote in message
T...
Alex Fraser wrote
Isn't expecting that "by far the most common case" is that a flipped
bit is written to before it is next read equivalent to saying that most
bits are written multiple times without being read inbetween?

Hmm. Maybe I just worked out the answer: processor caches result in
exactly that effect on main memory.

The experiment I propose would test this, speculation won't. The test
could be made with cache enabled and disabled, if possible.

****, what is it with people evading my questions, using them as an excuse
to repeat themselves?

With this sort of question, waffling away with speculation is pointless
when a fairly simple experiment can be made. I'm reminded of all the
experts who agreed that denser things fell faster than lighter things
until Galileo took the couple of minutes to drop balls of different
density from the tower of Pisa (or so it is said).

So I can't answer your question authoritatively (rather than evading
it). I did actually start drafting a response, but decided that it was a
waste of time.

Your experiment is an excellent idea. Sadly, I wouldn't know where to start
to implement it. Well, almost, anyway. Probably the most accessible method
would be to do it in the Linux kernel.

It would need to be done with each operating system for which we want to
know the answer.

If somebody knows how to enable a program to write to any location in
memory in Windows XP I might write and make available a program to
corrupt memory in the way I discussed. The answer is probably simple;
I've just never done anything like this since the days when the
operating system didn't protect memory.

Best wishes,
--
Michael Salem

I think sysinterns.com documents \Device\PhysicalMemory.

"Michael Salem" wrote in message
T...

It would need to be done with each operating system for which we want to
know the answer.

If somebody knows how to enable a program to write to any location in
memory in Windows XP I might write and make available a program to
corrupt memory in the way I discussed. The answer is probably simple;
I've just never done anything like this since the days when the
operating system didn't protect memory.

Michael Salem wrote:
Alex Fraser wrote:

.... snip ...

Your experiment is an excellent idea. Sadly, I wouldn't know
where to start to implement it. Well, almost, anyway. Probably
the most accessible method would be to do it in the Linux kernel.

It would need to be done with each operating system for which we
want to know the answer.

If somebody knows how to enable a program to write to any location
in memory in Windows XP I might write and make available a program
to corrupt memory in the way I discussed. The answer is probably
simple; I've just never done anything like this since the days
when the operating system didn't protect memory.

This link, which someone put up a short while ago, has a good
discussion of that very aspect, backed by some experiments. They
do tend to waste paper, though.

http://www.eecg.toronto.edu/~lie/papers/hp-softerrors-ieeetocs.pdf

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