> -----Original Message-----
> From: Edmund T [mailto:tedmund@singnet.com.sg]
> Hi,
> Do any kind soul have any ideal why my 16F877 work only when
> I pulldown all un-used port to ground?
> I used a 10k resistors to do that. Both VDD & VSS are
> connected and Pin 1 to reset. Chip running at 4Mhz.

Which ports do you consider unused, and how are they configured?  If the ports
are RB0, or RB4:RB7 and configured as inputs, you could be getting an interrupt
that you're not handling.

-Mike

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