"larz@s054.aone.net.au" <larz@s054.aone.net.au> wrote:
> Is there any way to "un-fuse" the read function of a 12C508 PIC? I want to
> compare the source code of one pic to another to see if maybe there's an
> inherent glitch in the code but the PIC turned out to be protected from
> reading the code.

It wouldn't be a very useful code protect if it could easily be turned off,
now would it?

I'm not sure about the 12C508 specifically, but most PICs use a simple
XOR hash function when you try to read them and the code protect bit is set.
If you really just want to compare the code in two PICs, one of which is
code protected, just set the code protect of the other one and compare the
hashed data.

Of all the requests that I receive via personal email for information
on defeating PIC code protection, it seems that the vast majority are from
people who want to copy the Playstation mod chips.  It's pretty silly,
since the source code is available on the net.  (Don't ask me where; use
Altavista or Lycos to find it yourself.)

Cheers,
Eric