Just a few comments about the feasability of zipping up a bunch of miles
on your electronic odometer with an oscillator....

    I wouldn't expect to be able to do this.  Not because the engineers at BMW are
putting in anti-fraud logic, but just because an automobile is a noisy, hostile
environment for electronics, and I would expect the software to be conservative.

   If I were to design a microprocessor-based odometer/speedometer program,
it would have the following features ( just off the top of my head ):

         * Debouncing/deglitching  ( Is this a real pulse, or just a glitch? )
         * Smoothing:  The rate-of-change of speed cannot be too high:
                                This is a car, not an electron.
         *  Top speed limit:  Anything above 200MPH is ridiculous: must be
                                        electrical noise or contact bounce

    As for getting in and presetting the pins:  if this is the circuit board out of
a BMW dashboard, I seem to remember a single big chip with lotsa pins in the
middle of the card.  Good luck getting at the counter :-).

    I wouldn't expect a high input frequency to damage the meter:  remember, it's
probably damped so it can't move too fast, and is probably protected.  After all,
a car is an extremely hostile place for delicate electronics;  there used to be an
app note in the National Semiconductor Linear Databook that went into this
in good detail.

                               - Jerry Kaidor ( tr2!jerry@dragoman.com, jkaidor@synoptics.com )
