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On Thu, 17 Jul 2008 09:16:46 +0200, scott wrote:
>> That seems most common - for implementations that involve life and
>> death, the systems tend to be custom-built for a specific purpose, not
>> based on a general purpose operating system.
>
> It's not just the software, all the hardware will also need to be
> certified for applications where human life is at risk. You think your
> PC is reliable? You trust it enough, that if it ever failed you'd die?
> Didn't think so :-)
Ah yes, absolutely true. :-)
Jim
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On Fri, 18 Jul 2008 03:38:31 -0400, Sabrina Kilian wrote:
> Jim Henderson wrote:
>> On Wed, 16 Jul 2008 09:17:21 -0700, Darren New wrote:
>>
>>> And I wouldn't be surprised, anyway, if some MS software had a bug
>>> that caused some patient to get over-dosed with radiation during
>>> cancer treatment or some such.
>>
>> I would be, since the machines that control that sort of thing tend to
>> be custom-built and not PC-controlled, at least not that I've seen
>> (admittedly, I've not spent a lot of time in cancer treatment
>> facilities).
>>
>> Jim
>
> Even the custom built control software isn't always bug free.
> http://en.wikipedia.org/wiki/Therac-25
Oh, sure, I wouldn't say they were, but special purpose machines with a
single purpose in life tend to be much easier to troubleshoot than a
complex general-purpose system.
Jim
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On Thu, 17 Jul 2008 14:37:15 +0100, Orchid XP v8 wrote:
> I'm sure temperature ranges were tested, but ice? Maybe they hadn't
> thought about that. IDK.
Having lived in Florida for a brief time, I can tell you that the general
feeling is the risk of ice forming is relatively low. Given that the
shuttle was designed to take off from KSC in Florida, it may well not
have been a design consideration.
Jim
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On Thu, 17 Jul 2008 08:29:13 EDT, "bluetree" <nomail@nomail> wrote:
>Stephen <mcavoysAT@aolDOTcom> wrote:
>> On Tue, 15 Jul 2008 17:41:00 +0100, Orchid XP v8 <voi### [at] dev null> wrote:
>>
>> >>> (PID - Andrew should know what this means, Proportional,
>> >>> Integral, Derivative )
>> >
>> >Andrew did *not* know what it means. I was assuming Process ID...
>>
>> Since when did you start speaking about yourself in the 3rd person?
>> :)
>Since he is at version 8? ;-)
>
Gosh! He is getting old :)
--
Regards
Stephen
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Orchid XP v8 wrote:
> NASA?
>
> Aren't they those guys who tried to launch a rocket with a faulty O-ring?
It wasn't exactly faulty, it just had poorly understood design limits.
Doing statistical analysis on the failures, they were all over the map.
Out of the thousands of variables that could have influenced the
O-ring failing, none had any statistical link to the failure rate.
After the Challenger exploded, they began running analysis on the times
that the O-Rings *didn't* fail, and found that a certain range of
temperatures coincided exactly with the successes.
So, the O-Ring was perfectly fine, as long as it was used within a
certain temperature range.
...Chambers
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Chambers wrote:
> So, the O-Ring was perfectly fine, as long as it was used within a
> certain temperature range.
A bit like saying "Micro$oft Word is perfectly fine, as long as you
don't try to use numebered lists". ;-)
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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And lo on Sun, 20 Jul 2008 20:58:24 +0100, Orchid XP v8 <voi### [at] devnull>
did spake, saying:
> Chambers wrote:
>
>> So, the O-Ring was perfectly fine, as long as it was used within a
>> certain temperature range.
>
> A bit like saying "Micro$oft Word is perfectly fine, as long as you
> don't try to use numebered lists". ;-)
Perhaps more like our military designing weapons and vehicles for use in
Europe (read Russia) and then sending them over to Iraq; they work fine
with the cold and the mud, but didn't like the heat and the sand. It's not
a design fault they simply weren't tested for conditions that they would
normally never have encountered.
--
Phil Cook
--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com
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> Perhaps more like our military designing weapons and vehicles for use in
> Europe (read Russia) and then sending them over to Iraq; they work fine
> with the cold and the mud, but didn't like the heat and the sand. It's not
> a design fault they simply weren't tested for conditions that they would
> normally never have encountered.
That's why we have specifications for everything. Included in the spec will
be operating and storage conditions, including temperature and humidity,
there will also be dust and water ingression specifications, which will
specify under exactly what conditions the device can be operated. If it's
operating outside the spec, the maker does not guarantee it will work. If
it's within the specified conditions and it fails, you ask for your money
back.
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>> It's not a design fault they simply weren't tested for conditions that
>> they would normally never have encountered.
>
> That's why we have specifications for everything.
It's a pity nobody ever does this for software, eh? ;-)
[Yes, I'm aware that a tiny percentage of people *do* in fact do this.
But it is such a tiny minority as to be almost non-existent. Unfortunately.]
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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And lo on Wed, 23 Jul 2008 09:44:10 +0100, scott <sco### [at] scottcom> did
spake, saying:
>> Perhaps more like our military designing weapons and vehicles for use
>> in Europe (read Russia) and then sending them over to Iraq; they work
>> fine with the cold and the mud, but didn't like the heat and the sand.
>> It's not a design fault they simply weren't tested for conditions that
>> they would normally never have encountered.
>
> That's why we have specifications for everything. Included in the spec
> will be operating and storage conditions, including temperature and
> humidity, there will also be dust and water ingression specifications,
> which will specify under exactly what conditions the device can be
> operated. If it's operating outside the spec, the maker does not
> guarantee it will work. If it's within the specified conditions and it
> fails, you ask for your money back.
Which was my point. You can't blame the manufacturers just the people who
decided to use whatever it is outside its specifications. In the case of
the weaponry the deployers should have asked if it would work in those
conditions and in the case of the Shuttle 'have all our launch parts been
tested at this abnormally low temperature?'.
--
Phil Cook
--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com
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