Re: Reverse Engineering-- Why Not?

[david@uow.edu.au (David E A Wilson)]

Andrew Roughan <posty@iggy.triode.net.au> writes:
>I know that there is a PAL/GAL reader, however it can't do 'protected' chips.
>Unfortunately, the TWGS GALs are protected.

It is certainly possible to read a protected PAL/GAL. The problem is that
it could take a long while and then might be difficult to get the original
fuse map.

For non register PALs you just apply every possible bit pattern to the inputs
and record the outputs. Then you apply standard minimisation principles to
this and work out the simplest fuse map.

Register PALs are harder - you can only apply some bit patterns yourself, the
others are the current state recorded in the output registers. The PAL could
have states into which it is impossible to get.
--
David Wilson	Dept CompSci Uni Wollongong Australia	david@cs.uow.edu.au