You&#x27;re right that Compaq went to a lot of reverse engineering effort, userbinator is also right about IBM releasing the source code for their BIOS.  They did it to prevent reverse engineering by tainting anyone exposed to the code. <a href="https:&#x2F;&#x2F;en.m.wikipedia.org&#x2F;wiki&#x2F;Phoenix_Technologies" rel="nofollow">https:&#x2F;&#x2F;en.m.wikipedia.org&#x2F;wiki&#x2F;Phoenix_Technologies</a>