Subject:
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Re: IR Tower not working when downloading firmware
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 11 Jan 2003 06:24:22 GMT
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Original-From:
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Steve Baker <{sjbaker1@}nomorespam{airmail.net}>
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Viewed:
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955 times
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Nick Tarleton wrote:
> Steve Baker wrote:
>
> > Touch the pins of the paperclip between pin 2 and 3
> > of one of the ports - and that port will echo every character
> > you send it...the other ports won't.
> >
> >
> Which physical pins are 2 and 3? I assume they would be the Tx and Rx pins,
> but I don't know where they are.
For a female connector:
5 4 3 2 1
* * * * *
* * * *
9 8 7 6
For a male connector:
1 2 3 4 5
* * * * *
* * * *
6 7 8 9
(The 'male' is the one with the pins - the 'female' is the
one with the holes)
> Pretty cool - data going through a paperclip.
Yes - I have some good Geek stories about that...
1) We once had a huge expensive mainframe computer you
could crash with a paperclip by doing the trick of
shorting pins 2 and 3 on a spare serial port (where you were
SUPPOSED to plug in a terminal or a modem or something).
What would happen would be that the computer would print
to the terminal: "System Ready" - then on the next line,
"Login:" - and expect you to type your username and password.
With the paperclip there, it would see the string 'System Ready'
sent back to it as the username - which would be invalid.
So the computer would print
"System Ready" is not a valid username
and then "Login:"...so then it would see that string entered
as the username - so it would reply:
""System Ready" is not a valid username" is not a valid username
and then say 'Login:' again. The message would get longer and
longer until after about 10 minutes, it's input buffer would
overflow and the computer would crash.
It was pretty cool to just stick a paperclip into the terminal port
and walk away - having started a 10 minute 'timebomb' that would
eventually crash a million dollar's worth of computer!
...OK maybe "childish" is a better word. :-)
2) In one application I was writing, we needed a reasonably accurate
interval delay interrupt in a DOS machine. All of the hardware
timers were used up - so the plan was to go out and purchase an
industrial controller card for the PC that had a suitable timer
on it. Unfortunately, the card cost many hundreds of dollars
(this was for VERY original 8088 IBM PC's - and all hardware
addons were expensive back then).
I had the bright idea of using a bent paperclip between two pins
of the serial port connector. By setting up an interrupt from
the serial port, then sending a single ASCII character to COM1:,
you could get an interrupt a short time later when the character
had been clocked out of the PC, through the paperclip and back
in again. By adjusting the baud rate, you could get pretty much
any amount of delay from about a millisecond up to about a quarter
of a second!
Saving the cost of the timer card was really worth-while in this product
and telling our customer (DisneyLand!) that they should install a
paperclip in order to make their ride work didn't seem too professional
- so we made up a little dummy plug that would go into the serial
port that had a short length of wire soldered between pins 2 and 3.
But in deference to my original design, this part was called "the BPC
plug" in all the documentation and system diagrams. Management never
knew what the acronym stood for - and that was never explained anywhere
in the manual. What it actually stood for was "Bent Paper Clip".
:-)
---------------------------- Steve Baker -------------------------
HomeEmail: <sjbaker1@airmail.net> WorkEmail: <sjbaker@link.com>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net http://tuxaqfh.sf.net
http://tuxkart.sf.net http://prettypoly.sf.net
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