On Thu, 13 Feb 1997, Mike wrote:

> >David,
> >
> >   Not that it is any consolation but I am looking at 3 PIC16C62A/JWs
> >   out of a group of 5 that I had been using.  These 3 all mysteriously
> >   got code protected.  Even though I have been especially careful and
> >   am using a Microchip Promate programmer, it still happened.
>
> I understand that on HC705 series any code protection is via EPROM bit,
> I infer that code protection on PIC is via a fuse and therefore cannot
> be erased by UV ?

Yeah I'd imagine so !

>
> Does this also apply to the flash parts - wouldn't it be more efficient
> that the code protection be via EPROM type bit anyway ?
>
> Are there any moves by microchip (hi guys) to change to EPROM bit ?
>
        I hate to say it but  I recon judging by previous discussions I
have heard that the move was actually in the other direction. I reckon
that it may have been due to a worry by microchip that one may be able to
selectively erase parts of the windowed chip using perhaps a fine laser
beam or something. And by doing so only wipe the CP bit.. I.e. exposing
the protected code..
        I am no expert on the subject so all I have just said is purely
hearsay. Please correct me if I'm wrong in those assumptions.
        However on the note of Microchip doing something about the problem
I would suggest and hope I'm taken seriously that a variant of the
windowed chip be produced that has no code protect bit.. Surely this
wouldn't be difficult (I realise Chip changes incur fabrication costs )
but I believe there would definately be a large market for such chips as
most developers have no need to code protect their windowed versions..
It's easier to lock them in your drawer ! Could anyone who agrees with
this suggestion please voice your support to confrim such a market.





> And in any case since I hear that all code protected PIC parts are just
> as easy to read as the code protected motorola parts - wouldn't it be
> logical that a code protect chip could be erased and reused ?
>

        Hmmmm, Are you sure on that one ? I'm sure microchip wouldn't be
impressed !

> Rgds
>
>
> Mike
>


                                        Dave.



http://www.csn.ul.ie/~david