[sdiy] Protected PAL/GAL reading service?

Magnus Danielson magnus at rubidium.dyndns.org
Mon Feb 18 00:01:20 CET 2013

On 02/17/2013 11:08 PM, Rainer Buchty wrote:
> On Sat, 16 Feb 2013, Tom Arnold wrote:
>> I have a couple 16L8 PALs I need the contents of. Can anyone recommend
>> a service for doing this sort of recovery?
> 16*L*8?
> Security fuses don't make much sense there ... If everything fails, just
> wire it to an EPROM socket and read the output bit pattern ("data") for
> each input bit pattern ("address").
> Then just create an EPROM of same content and wire it to the PAL socket.
> And if you really want the equations, feed the dump into a
> Quine-McCluskey minimizer or just do a batch-driven source generation
> (be it PALAM, ABEL, or VHDL), feed that into your favorite tool for
> minimization, and let it dump the minimized equations.

Does not always help. If internal feedback is being used, then it 
becomes a bit more tricky. In the PPG Wave 2.3 PALs, the feedback 
available on chip was not used, so it was wired on the board for one of 
the PALs. Ah well.

Still, It is relatively easy to figure out. Also, for most PAL designs, 
half of it you can guess pretty much from the surrounding design anyway.

It would not be too hard for something like a Raspberry Pi or something 
to "crack" PALs with feedback. A bit of soldering and a bit of software, 
hook it up and let it sit there and test it out. Would be a fun little 
programming project. I'll put it in the pile.


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