As already mentioned, you don't 'write protect' them (what good would that do?), you 'read protect' so they can't be copied by any third party.Guided missiles would have they're own special write protecting system!?
Yup it's a 94 era tech we are working on... we have an appropriate programmer and our repro chips are successfully accepting the logic programs and working fine in our new boards.
It's taken along time and a lot of work so ideally we'd like to write protect them but can't seem to work out how to do it or where the security 'bit is? I was just wondering if anyone can help?