The first few pic circuits I built were very tempramental some days they
would start up some days they wouldn't, I was realy puzzled. Then I
noticed that when I checked the voltages around the 16F84 pins just
touching the MCLR pin would bring the circuit to life. So I changed the
reset pull up from a simple resistor to Vcc to the one shown in the pic
manual (with a diode and capacitor) since then I have not had this
problem with any of the many 16F84 circuits I have built.

---- John

 On Thu, 30 Nov 2000, Peter L. Peres wrote:

> This is the typical symptom of a PIC (or other CMOS processor) not
> starting from Reset. If power comes too slowly or if it does not go low
> enough to make the internal reset circuit notice it is low then the
> processor will start (or continue) execution from an undefined state. To
> confirm, use a reset button temporarily mounted on MCLR. If this always
> fixes the problem, then a reset monitor or watchdog on operation is a good
> idea imho.
>
> Peter
>
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