Marc wrote:
>
> Hi.  Today I have trashed two 16C711 JW devices.  Although I
> spent a lot of attention to the code protection being set to OFF,
> both chips reported a programming error, namely the CP setting
> "illegal".
>
> Both are now not erasable anymore and ready for the trashcan.

So try baking them in high (150C) temperature oven for a while.
You've got nothing to loose. High temperature causes higher
leakage and may be able to drain off the buried charge on the
code protect bit. High temperatures are really only a packaging
problem, and in the JW case you can go REALLY high (after all
they fab the IC's at 1000's of degrees C).

If you have access to an x-ray machine, try blasting them with
low energy x-rays. That WILL remove the charge.
Someone on this list probably knows what dose would work.