Another interesting scheme I once heard about was to purposely blow a
particular chip or diode or transistor, and put it in the circuit. If
someone copied your circuit exactly, they'd put in a working component,
and your firmware would detect that and refuse to run. I've never
bothered to figure out what would work best. Probably a diode...cheap,
and fairly easy to destroy.

Josh Koffman
joshy@mb.sympatico.ca

Chris Eddy wrote:
>
> Oh, that is VERY good.   Gives me chills.  I think I will use that some time in the
> future.
>
> That is similar to a protection scheme that I heard sometime ago, probably on the
> list..
>
> Hide a special key sequence in your menu system.  If the competitor steals your
> code, then you can call in your trump card right there in front of the jury.
>
> > A slave will only accept commands after it has received a message "COPYRIGHT
> > XXXX" where XXX is the company name and copyright date.