Re: For the TWGS and The Zip cards

[ToasterKing <ToasterKing@mindlessPLOP.com (Delete "PLOP" to reply)>]

In article <1dplt5n.cbyf7q1bmzbrtN@dempson.actrix.gen.nz> David Empson,
dempson@actrix.gen.nz writes:
>The million dollar question for this is whether anyone has the source
>file for the GAL.  In 99% of the cases I've encountered, PALs, GALs and
>the like have a protection mechanism that prevents their internal logic
>being read back by the programmer, after a protection fuse is blown.
>
>We use OTP and Flash PALs at work, and both types have this feature.
>Our programming software automatically blows it unless you do each
>programming step manually (blank check, program, verify).

Wow.  I had no idea that such a thing as a protection fuse was possible
in this case.  Of course, I know nothing about burning chips and/or
obtaining source data from the chip, etc.  If it's easy to explain, what
exactly happens (electrically) when an attempt to read the data is made
that causes the internal fuse to be blown?  If you could explain it, I'd
be really intrigued to know.

And I suppose I was right about the original GAL chipset also slowing
down instructions?

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