It used to be very common to use lasers on a microchip before it was packaged. You would test the microchip and based on the test results, pass coordinates to a laser telling it where to burn. This gave you the opportunity to fix bad chips or program customer specific information.
This is still done at a lot of companies that use older manufacturing processes.
The switch to EEPROMs and similar methodologies has happened in the last 20 years.
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