sine wave on an oscilloscope but the idea is kind of like reading
an EEG or electroencephalogram or an EKG, electrocardiogram. You
can't tell what a person is thinking during an
electroencephalogram, but you can make generalizations as to
whether or not the person has signs of life, is asleep or awake
or having abnormal activity such as epilepsy.
I have used radios to do something similar when messing
with computers and you can tell by listening to the static
whether or not something useful is going on or the thing is dead
as a door nail. When a computer is doing something, one can hear
organized chaos with zips, pops, squeals, sort of like listening
to whales. If it is locked up or dead, there is either nothing
coming from the box or maybe a steady bunch of carriers that
sound like a radio station with nothing on the air. You just have
to train your ears.
This is very handy when working with PIC microcontrollers
or other single-chip computers. If they go off in to Never-Never
land, it is nice to know if they are really dead or just a little
sick.
PIC microcontrollers have a sleep instruction which makes
the chip stop it's event clock and turn off all outputs such as
if you build some device that runs on batteries and saving
batteries is important, you want the device to go to sleep
between uses. You can program some PIC's to wake up from sleep if
a particular pin changes state. If one goofs in his or her
program, you may cause the PIC to go to sleep when it shouldn't
and a small short wave radio tuned to the clock frequency will
suddenly stop showing any signal when you know it should still be
working.
If I have a Linux box in front of me and it should be
talking, a radio can tell me if it started to boot and is hung
now or if it probably booted but isn't talking.
Sorry for the length of this post, but the more tricks
you know, the more likely you are to get stuff working.
Martin
Jude DaShiell <jdashiel@xxxxxxxxx> wrote:
> I bet Martin even remembers how to use an oscilloscope to repair a
> computer
> too.
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