> That should be no problem; I use a stabilized lab power supply set to 13 V for
> Vpp, and a 7805 for getting Vdd. But as I said, the very first read to verify
> the very first word programmed fails with "read 3FFF, expected
> 0186".
>
> So how can I verify that either the circuit or the 16F84 is bad?
> Any hints appreciated!
> Thanks,
> Franz


Hello Franz,

Do you use the pp05-Software (it really suports a 16F(!)84)? If not, I
can send you a copy. And I hope you use the PNP-switches and not the
CMOS 4066...
There is a hardware-debugging-mode in this software, just set the
environment variable PPDEBUG=1 (default=0) and run pp.exe without any
parameters. Now you can toggle each LPT-pin you are using with your
programmer.
How long is your cable? It should be less than 0,5m! Which type of
processor do have in your PC? Maybe you should disable the cache-memory
before burning, if you have timig problems.

Happy debugging!
Markus Rohe