Graham wrote:

> I have found though that when I apply power while MCLR is low, wait a
> couple of seconds, then let MCLR go high through a pull-up resistor,
> it works every time.  This could mean that the power line takes that
> long to stabilize, which is very strange!

  Use the "brownout" circuit from the application notes.  One PNP
transistor and three resistors, Figure 8-15 of document DS30430C, page
46.

  As I see it, it is unwise *not* to use this circuit or a better one,
in any PIC application.

  Why isn't it built-in?  Well, if it were, it would limit you to a
specific voltage range for circuit operation.  It is expected that you
design this circuit for whatever operating voltage you will be using,
taking into account the characteristics of other associated devices.

  The circuit also uses a few microamps in operation.

  Of course, they *could* have included some sort of very low current,
1V threshold device I suppose.
--
  Cheers,
        Paul B.