Hi Wouter,
        Thanks for your reply. Although it wasn't what I wished to hear it
does clarify somewhat. However I do have a thought which may prove to be of
help for my requirement. It all hinges on whether the PICSTART always does a
bulk erase or not. If it does then I'll have to look at a more "flexible"
programmer.
On reading the programming spec I see that there is selective code
protection for blocks of memory. This means that initially I can programme
the first piece of code and protect the block (e.g. 400 -7ff). Now if I come
along later and selectively write to the remaining memory(e.g. 0 -3ff) - but
without doing a bulk erase first - I can get in the second part of the code.
The issue I see here is that if I then want to protect all the code it could
cause a bulk erase which puts me back at square one.
My gut feel on this issue is that if I leave the configuration word at it's
unprogrammed state ( all 1s - I'm assuming) and just write a zero to the one
bit for the 400 - 7ff block protection, I can then set all the other bits
(low) as required on the second programming run. I don't think this would
constitute a "reset" of the configuration word and thus no bulk erase
caused.

What do you think?

Slan
John

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