In message  <3.0.16.19970424104738.526f601a@pop3.nw.com.br>
 PICLIST@MITVMA.MIT.EDU writes:
> At 18:35 23/04/97 -0800, Andrew Warren wrote:
> >> Erasing the [Code Protect] bit after (or even together with) all
> >> the program data doesn't seem like stealing code...
> >
> >    Right, Gerhard... But how would you ensure that the bit gets
> >    erased AFTER the program data?
>
> It seems possible to influence the "erasability" of memory bits by design.
> They could put the configuration bits in a memory different from program
> memory, thus making sure that they get erased after the program.
>
> Tjaart seems to agree with me, I just read in another message. I think it
> could be really helpful to be able to deliver completely erasable (and
> therefore reprogrammable) chips _with_ (erasable) memory protection.
>

This is how it used to be on many of the older PICs (16C5x, C71, C61...),
but it was changed for a reason - the reason being that it was too easy
to defeat the copy protection.

If Andy Kunz is right (and I don't doubt him) over-cooking a code
protected part in a UV light will erase the code protect bit.


Regards,


Mike Watson
--
Mayes uk