Generically, it would be referred to as &quot;OTP NVM&quot;, or one time programmable non-volatile memory.<p>There are apparently a few different ways to implement that.<p>A little dry, but the only thing I could find with some comparison of approaches: <a href="http:&#x2F;&#x2F;www.kilopass.com&#x2F;wp-content&#x2F;uploads&#x2F;2010&#x2F;04&#x2F;comparison_of_embedded_nvm.pdf" rel="nofollow">http:&#x2F;&#x2F;www.kilopass.com&#x2F;wp-content&#x2F;uploads&#x2F;2010&#x2F;04&#x2F;compariso...</a>