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Orchid XP v8 schrieb:
> Interesting thing: According to Wikipedia [which is never wrong], a
> nuclear explosion only generates an EMP because of the Earth's magnetic
> field. Like, if it was in space, it wouldn't do that...
I think I heard it was the atmosphere, not the magnetic field...
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On Tue, 10 Nov 2009 15:25:18 +0000, Invisible wrote:
>>> Tape operates at much lower speeds. And since the only people who use
>>> tape are people who want seriously reliable backup storage, it tends
>>> to be very well engineered. (And stupidly expensive...)
>>
>> Never used DAT drives for backup, have you? ;-)
>
> No, only for the last 6 years.
I feel for you. I had tapes that actually verified nightly that were
completely useless to restore from. This is back in the DDS-1/DDS-2
days, so maybe it's improved - but here's the thing: DAT stands for
"Digital Audio Tape".
Q. What's one difference between audio and data?
A. You can lose some audio data and not notice it. You can't lose data
and not notice it.
Using "audio tape" for backup (digital or no) is generally not a good
idea. It was designed for audio, not data.
>> Horrible quality of storage media, and terrible shelf life IME.
>
> Really?
Yes, really. With the DDS-2 tapes I was using at the time, the
manufacturer recommended no more than something like 10 or 20 uses.
The tape also creates friction against the recording head, which rotates
in a direction that's counter to the tape direction, so the tape drives
burn out fairly easily. I used to have a Compaq 4/16 DAT autochanger for
my home server, along with a couple of standalone DAT drives, and I
burned the heads out on *all* of them while doing alpha and beta testing
of backup software.
I'm glad I didn't pay for the drives - otherwise I'd have been more upset
that they burned out so quickly (about a year, IIRC - but I was running
backups on a more or less continuous basis as part of my testing).
I had much better luck with DLT drives.
Jim
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On Tue, 10 Nov 2009 15:27:57 +0000, Invisible wrote:
>>> I often buy from Maplin because 1) I don't have to wait for it to be
>>> delivered, 2) their staff actually have a frickin clue, and 3) they
>>> don't argue about returns.
>>
>> Sometimes expediency is worth the extra cost - as is the ability to get
>> something replaced without a hassle.
>
> Maplin are pretty much the best electronics shop around.
>
> I mean, apart from being the *only* place in all of Christendom which
> can sell you (say) a 50kohm resistor, their staff have a clue about what
> they're supposed to be selling, and if you take something back they will
> exchange it or give you your money back (provided it isn't obviously
> busted).
>
> Their website utterly sucks, by the way...
Everyone's bad at something. ;-)
Jim
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Stefan Viljoen wrote:
> Its like Captain Picard saying "Full stop!" on the Enterprise, and in ten
> seconds they are at relative dead stop from going several hundred times
> lightspeed.
Clearly they're manipulating gravity, so that's not really a problem. You
can accelerate from 0 to 0.99c in seconds via frame dragging if you don't
have to deal with tidal forces.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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On Tue, 10 Nov 2009 11:12:57 +0100, Invisible <voi### [at] dev null> wrote:
>
> In theory, until the disks are spinning at full speed, you don't get
> that "cushion of air" for the heads to "fly" on, which should result in
> wear. Of course, no doubt manufacturers know all about this and have
> come up with ways to at least reduce the problem...
http://www.storagereview.com/guide2000/ref/hdd/op/actParking.html
http://www.wdc.com/en/library/eide/79-880134.pdf
--
FE
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Invisible wrote:
> Yeah. Amazing how all sentient beings are humanoids who just happen to
> speak American English, eh?
Except precisely when the plot requires otherwise. :-)
> I have no idea what the hell kind of energy it possesses.
Negative energy (and negative gravity, for that matter). That's how you get
the time-travel part from exotic matter.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Stefan Viljoen schrieb:
> Huh? That doesn't sound right. An old strategic option the USSR apparently
> had was to detonate a -real- big (50 megaton) thermonuke over the US, but
> out in space / low orbit. The idea was to melt all radios and computers,
> the entire US telephone network, etc. As far as I know EMP damage is caused
> by the massive radio waves generated by a nuclear explosion (besides all
> the "hard" gamma radiation, and other nasty stuff besides heat and light).
> These induce current in conductors (i. e. they fry microchips).
I think the story is slightly different:
- A nuclear explosion is caused by nuclear fission and/or fusion
(actually primarily fission, even in a thermonuke aka H-bomb); the
radiation given off by this is primarily gamma rays.
- As the gamma rays hit the atmosphere, they ionize it, turning it into
a plasma.
- The plasma in turn "glows" in the whole EM spectrum.
> Radio definitely travels in a vacuum where there is no magnetism - IMO,
> magnetism CAN effect radio but just to distort or interfere with it. So I'd
> think that a magnetic field will -moderate- or interfere an EMP pulse a
> bit, not be the part-cause of it?
Mind that the earth's magnetic field does not stop outside the atmosphere...
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Stefan Viljoen wrote:
> It just somehow... sad.
Check out some of Greg Egan's stories about the Aloof. Luminous (short
stories) or Incandescence for example. Folks live a very, very long time,
and regularly travel as data around the galaxy, but it's still light speed.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Invisible wrote:
>>> Wait - your garage door can open by itself?
>>>
>>> Man, if we want to open ours, we have to use *muscle power*. ;-)
>>
>> Hey, that's the U.S. of A. - they don't use muscle power for
>> /anything/, unless they happen to be football pros...
>
> I thought baseball was the national game of America?
Baseball doesn't take muscle power. Except maybe the pitcher.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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>> Interesting thing: According to Wikipedia [which is never wrong], a
>> nuclear explosion only generates an EMP because of the Earth's
>> magnetic field. Like, if it was in space, it wouldn't do that...
>
> I think I heard it was the atmosphere, not the magnetic field...
Seems the gamma rays generate a current in the atmosphere [which
wouldn't happen if there was no atmosphere], and the magnetic field
channels this to the ground [in certain parts of the globe which happen
to include the USA].
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