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Someone once wrote, "Any sufficiently advanced technology is indistinguishable from magic." Depending on your personal technology level some of this stuff, especially the things that can go wrong, seems like magic. Heck, I'm an engineer and have spent a (depressingly) large amount of time in my career chasing down slippery problems. (But then if it weren't for problems there would be an awful lot of unemployed engineers.) Of course, once you get the problem fixed and look back at how you arrived at the solution you invariably think, this should have been obvious! Ah, the wonders of 20/20 hindsight.
Have fun chasing those electrons.
Tom Gourley
----- Original Message ----- From: "Marvin Kaye" <marv@lancaironline.net>
To: "Lancair Mailing List" <lml@lancaironline.net>
Sent: Wednesday, April 19, 2006 7:56 PM
Subject: [LML] Re: Avionics: Black Art or Science
Posted for "Halle, John" <JJHALLE@stoel.com>:
Brent writes (below) that electrons follow rules that can (sooner or later)
be understood through the use of reason. Reminds me of the story about the
lawyer who wrote a one-page legal document and sent a bill for $500 with a
single item: "draft document: $500." The client objected that it could not
have taken more than a half hour to write the document. The lawyer sent back
a revised bill with two items: 1. "draft document: $50"; 2. "knowing what to
write: $450."
Having just finished replacing my panel, I must, at least superficially agree
with Brent. The problem is that, as anyone who has ever looked at the back of
a modern instrument panel knows, there are electrons going through hundreds of
wires. Some of them are carrying digital data (whether the electrons are
analog or not) that may be AIRINC, RS232 or something else, some are carrying
a simple current that is used to power something; some are carrying a current
that is used to transmit data. A huge number of them are going to something
called "ground", a simple concept until you try to actually do it right. They
go to and from various boxes that have unbelievebly complex circuits etched
onto chips and other devices. These boxes either do or don't talk to each
other using protocols understood only by software engineers. In theory we
don't have to understand how all this works because all we have to do is
follow the installation and setup directions, 100% of which are wrong or
incomplete in some respect and many of which are almost totally wrong or
incomplete. If something is not working properly, there are usually at least
ten possible explanations that occur even to a non-engineer, to say nothing of
the fifty explanations that occur to engineers. Each one of these
explanations involves the assumption that electrons follow simple rules that
can be understood through the use of reason. The black art is knowing which
explanation to investigate first.
--
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