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'Code protect'
1995\04\26@155949 by David Tait

Amazing!  I have been sitting on the information about reading
protected 16C84s since March 1st 1995, but the very day I decide to
make it public, the same method is posted to
(see Lester Wilson's entry to the NEW PROGRAMMER thread).  In fact the
info there is a copy of a file I was asked to supply with my
programmer software and pre-dates the stuff included in my last

Lester Wilson advertises hardware to read and write all types of ISO
7816 smart cards and program PIC16C84s.  I'm not sure his case would
be well served by making a working technique available to all and
perhaps there is a flaw in the method after all.  On the other hand
convincing punters that it is possible might increase his sales.  I
note his posting ends with these words: "I have used methods SIMILAR
to the above to achieve the same result."

This is my last posting on this subject.  I'm sorry to debase this
erudite mail list with such unsavoury matters.


1995\04\26@165225 by David Tait

I think a null message escaped - sorry about that.

Anyway, I'm glad the code protect topic has come up again because it will
let me get this off my chest - sorry it's so long.

The security of the PIC code protection mechanism has been discussed
many times before.  It has even been discussed on the Microchip BBS:
in Message 61000 of the "Relablty" SIG David Wilkie of Microchip
ends one such thread with the soothing: "I assure you that the code is
safe once the protection bit is activated."

The vulnerability of the 16C84 is of particular concern. The 16C84 is
often used in smart cards issued by the satellite TV industry.  These
cards are intended to permit access to encrypted TV channels, and
clearly there is a lot of interest in being able to clone the cards
thereby avoiding payment to the TV providers.  This means the
protection topic is endlessly discussed in newsgroups like  Every so often this newsgroup carries
adverts for hardware which is claimed to be capable of reading
protected PICs.  I have always been skeptical of these claims.  I have
changed my mind.

The fact that I provide information on a homebrew 16C84 programmer
means that I often get asked whether I know how to read protected
PICs.  Recently an interesting situation arose.  I received yet
another request for this information at exactly the same time that
someone happened to send me details of a technique claimed to
unprotect PICs.  I simply passed these on from one correspondent to
the other.  Much to my surprise the requester later wrote back to say
the technique worked (but he destroyed 3 PICs in the attempt).  The
originator of the method is happy for the information to be placed in
the public domain although he wants to remain anonymous for some
reason.  So for the benefit of PICLIST readers (and I know that
includes Microchip employees) here are his instructions more or less
verbatim (although the description is tied to his programmer the other
guy used a variant of mine):

{Quote hidden}

I must admit it looks like a surefire way to destroy PICs to me so I
haven't tried it myself even though the originator claims that he has
never fried a 16C84 this way.  I realise the fact that I have never
tried it myself means that all this is just hearsay, but although
there are some points left to the imagination, the description is
explicit enough to be tested by those worried by such things.

I have no idea whether the method is related to Bela Gebles
<> technique, but if you think this info is
worth GBP1000, then like him, I'll be happy to give you my bank
account details :-)  On the other hand if you think it's all hogwash,
then I'm sorry to have wasted your time.


'code protect'
1997\02\17@140335 by tumilty
picon face
Can antone help me I code protected my pic16c71jw by mistake and now i
can't seem to blank it, is history

'Code Protect'
1998\01\31@193011 by David Sprenkle
I am new to the list and I am sure this question has been asked before
but does anyone know how secure your code is on the PIC16C5XX and
PIC12C5XXX series with the code protect bit on..

David Sprenkle

'Code protect'
1999\01\13@004454 by Tony Nixon
picon face
Hi all,

Just for info, I just had a look at this web site.

It claims to be making a PIC copier that can copy 16F84's as well as
16C84's even when code protected.

Also, even more interesting, being able to program the code protect fuse
'a special way' so that it can be reset easily.

Maybe, programming the fuse at a low VCC may weakly set it or

Best regards


Multimedia 16F84 Beginners PIC Tools.
** NEW PicNPro Programmer and Port Interface **

1999\01\13@172629 by Tony Nixon

picon face
Perhaps if I give the site address.....duhh!

Best regards


Multimedia 16F84 Beginners PIC Tools.
** NEW PicNPro Programmer and Port Interface **

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