Re: how can a bit be off in memory?

Jean-David Beyer wrote:
The Natural Philosopher wrote:

> Never believe that computers are 100% reliable,. A friend spent some
time years ago developing hardware: they ran into an interrupt timing
issue. Every 4-5 hours the machine would crash when a timer interrupt
interrupted a particular piece of code. For reasons deep and complex,
they couldn't turn interrupts off, but the managed to re-code the bit of
code so the offending part was very small, and they calculated the crash
would occur only once in every 5 years or so.

They left it that way, knowing that occasionally a user would scratch
his head, reboot, and shrug his shoulders 'I wonder what THAT was?' :-)
:-)

If they left it like that, I hope one of their systems controlled an
essential piece of equipment in the Intensive Care Unit of the local
hospital when that designer needed care!


Hardly: This was a 'home computer' - remember those? Acorn atom IIRC.

I designed some software to deal with a concurrent update problem in a dbms.
The project managers said my solution had too much disk overhead and did
double the IO and made me remove it. It added only 8 bytes per record, and
did not double the IO: it added 1 IO to a task that already used 10 or a
little more. They insisted that the odds of a problem were greater than a
million to one against. (I had calculated that they were about 6000 to one
against or something like that.) I said that granting their figures, we
would have a problem every two weeks. But they would not allow my solution
into the product. Well, we had a problem in the first week. By then, the
database design was frozen, so they had to use manual methods to prevent
multiple people updating the same record at the same time. Needless to say,
that did not work and eventually the system was scrapped.

Sounds like every other health database I have ever heard of..
.

Relevant Pages

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    (microsoft.public.development.device.drivers)
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  • Re: Filter Hook
    ... Windows 2k/XP/2k3 Filesystem and Driver Consulting ... use IoConnectInterrupt with a software interrupt. ... What IRQL are you running at when you crash, ...
    (microsoft.public.development.device.drivers)
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    ... A filter hook driver should not have an interrupt handler it is only ... What IRQL are you running at when you crash, a common problem here would be ... I have tried to set up a Filter Hook driver. ... "IoConnectInterrupt" from the isrStack). ...
    (microsoft.public.development.device.drivers)
  • Re: Filter Hook
    ... use IoConnectInterrupt with a software interrupt. ... What IRQL are you running at when you crash, a common problem here would be ... Windows 2k/XP/2k3 Filesystem and Driver Consulting ... "IoConnectInterrupt" from the isrStack). ...
    (microsoft.public.development.device.drivers)