>Mmm... good point, they specifically refer to voltage spikes below Vss.
>
>Perhaps they are concerned about parasitics in long wires running to a
>reset switch or something along that line. I regularly tie the output of
>the BOR circuit directly to /MCLR with a very short conductor along a
>ground plane. Can't see any reason to add the extra resistor...

I think it has more to do with driving the programming circuitry when it
should not. Consider that under programming conditions you have 13V on this
pin, i.e. 8V higher than Vcc. Now if you have 5V on this pin due to large
capacitor, and no other supply to the chip, what is happening inside the
programming enable circuitry? I suspect some large currents can flow because
devices are not biased correctly and things get destroyed in the manner
described by someone else.

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