Re: Help to copy PAL16 / GAL16 / GAL20 ICs

In article <HI6dnVXuwNMM_XDfRVn-oA@xxxxxxxxxxx>, apl2research@xxxxxxxxxxx says...

> I'm currently working on a project to "clone" some old computer boards I
> have. The companies are long since out of business. These boards are from
> around 1983 to 1985.

> I'm researching in to copying a few of the PAL16 / GAL16 / GAL20 ICs on
> these boards. I've been reading that it is possible to "read protect"
> (aka - registered) these chips and fear I may run in to this issue.

<snippety>

The protection you mention refers to disabling a device programmer's ability to read
the JEDEC fuse pattern burned into the PAL during initial programming. It's more commonly
referred to as the 'Security Fuse.'

If the security fuse has indeed been blown, you will not be able to read the PAL in
question. Reverse-engineering is possible, but it will likely require a logic analyzer. It
will also most definitely require schematic diagrams of the circuit in question, showing how
the PAL you're trying to reverse-engineer works into the circuit. Source code for the
circuit's microprocessor for the specific application may also be of assistance (good luck).

As far as a programmer goes, the Pilot MVP is an excellent choice. Don't think of it
as "more than you need." Think of it instead as a relatively future-proof investment. It is a
tool, and a quality one at that, one which will serve your needs for much more than just
PALs.

> I'm also looking for someone to help or "tutor" me with these PAL/GAL ICs
> and I'd be willing to pay for this service.

Such training could be hard to find. I'm not a good choice, as my knowledge of such
devices is still at the "basic" level, and I don't make a very good tutor in any case (wrong
personality for it). I would suggest checking with your local community colleges for
electronics courses involving basic digital logic and PALs.

Happy hunting.

.

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