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reading "secure" GAL chips

Discussion in 'Electronic Repair' started by Ray Carlsen, Oct 23, 2012.

  1. Ray Carlsen

    Ray Carlsen Guest

    I know they are almost a thing of the past but I wonder if there is
    any way to extract the code from a protected GAL IC (example: GAL16V8A)
    that has had its security bit set.
    I repair mostly old Commodore 8 bit computers. There are a lot of
    users of an after-market device called a RAMLink originally made by
    Creative Micro Designs (CMD is now out of business) back in the 1980's,
    and I was asked to repair a few of them. Turns out each one has four or
    five GALs and they all are copy protected which makes repair of those
    orphan devices impossible unless I can find a way to extract the code
    from the chips in a working unit. Any hackers out there?

    Ray
     
  2. It was told to be software that presented series of input signals to the
    PAL/GAL that searched for the fuse pattern rather then the logic. But I
    never found it. Off course, combinatorial can be found easily. A pre
    NT/2000/XP machine with a parallel printerport - preferable EPP - , a little
    hardware and some old fashioned GWBASIC programming will do that job quite
    easily. But the moment there are state machines inside, you're out of luck.
    The only time I needed to reverse engineer a PAL like that, it was
    relatively easy to find out the function from the schematic. I suppose it is
    still the best thing to do. Off course, one can still go for the ultimate
    PAL cracker but is it worth the time and the effort?

    petrus bitbyter
     
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