Reprogrammable ROM with jumpers for write-protect is what I did in mine way back. Even game consoles had removable ROM on cartridges. ;) Another scheme, independently designed before me, was to use two memories with a ROM being root-of-trust with trusted boot and flash having most firmware for update purposes.<p>Far as Joanna&#x27;s idea, this has been done before twice. I posted a business and legal analysis of it here:<p><a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=10788617" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=10788617</a><p>What do you think of the analysis? Aside from I should patent my ideas more. ;)