Marc wrote:

> Make sure that 13V programming voltage is _stiff_ and has _quick_ rise
> time. If it is slow, the PIC might start executing instructions while
> MCLR travels through 2-7V on its way to 13V.  Executing instructions
> increments PC, which is used as address pointer during programming.
> I made a programmer once with the 14V/0V decision made by an NPN and
> pullup to 13V. It didn't work reliable for that very reason: the rise
> time was just too slow.

  Ahem!  What you mention applies to ISP programmers.  It does *not*
AFAIK apply to stand-alone programmers as - they have no crystal or RC
to oscillate!  (Unlike AVR programming.)

  No oscillator - no clocking - no execution of instructions/ no
increment of PC.

  If you want to be sure, provide a link (across the capacitor) to
ground OSC1 whilst programming.

  If you have no crystal or OSC1 is grounded and it still malfunctions,
look elsewhere than the MCLR risetime.
--
  Cheers,
        Paul B.