Wow !
                Would anyone else like to confirm this mail. (That even
new pics can have CP bit erased given enough UV light ). Not that I'm
doubting you Mike just curious if Microchip would like to confirm that
this is a design feature rather than a fault in Mike's chips...

                                Thanks..
                                                David.




On Mon, 24 Feb 1997, Andy Kunz wrote:

> At 08:57 AM 2/24/97 -0800, you wrote:
> >I wrote:
> >
> >> For many of the new PICs, enabling the Code Protection WILL prevent
> >> the chips from being erased.
> >
> >    I suppose some clarification is in order, since I've received a
> >    number of incredulous private responses to that statement:
> >
> >    On the newer PICs, the code-protect bits don't erase because
> >    they're physically shielded from UV light.  The rest of the
> >    memory WILL erase, but that doesn't matter since the devices
> >    can't be reprogrammed while the code-protection is enabled.
> >
> >    So... If you code-protect one of the newer PICs, you won't be
> >    able to reprogram it, even though you CAN erase most of it.
>
> You CAN erase all of it.  It just takes time.  The metal shield prevents the
> light from coming in easily.  It still gets there, and I have the chips to
> prove it.  I use them almost daily.
>
> Microchip made several other changes to the newer parts (often the "A" or
> 3-digit part) in order to foil the hackers, but they can only go so far.
> The shield causes light to be attenuated immensely, but it still gets
> through enough to reuse the chip after a 2-hour or so suntan.
>
> Please don't mislead folks into thinking that protected windowed parts that
> don't seem to erase after the normal time are garbage.  Unless, guys, you
> want to send them to me instead.  I'll throw them away for you <G>
>
> Andy
> ==================================================================
> Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865
>           Hardware & Software for Industry & R/C Hobbies
>         "Go fast, turn right, and keep the wet side down!"
> ==================================================================
>