[Read your NDA carefully. It will tell you some of this. I can't quote from any of the ones I signed because they all include clauses that say I can't do that, but read your own in detail. Also keep in mind that overly broad NDAs are often set aside by courts, so if you act reasonably you will not be attracting legal or ethical jeopardy.] Let's say as part of working on X you learned a true fact like "A is faster than B" or "these screws don't rust in the environment X is deployed in" or "you sh...