If you want to understand just a tiny piece of it, check out this great article about how the overflow flag is implemented in hardware on the 6502:<p><a href="http:&#x2F;&#x2F;www.righto.com&#x2F;2013&#x2F;01&#x2F;a-small-part-of-6502-chip-explained.html" rel="nofollow">http:&#x2F;&#x2F;www.righto.com&#x2F;2013&#x2F;01&#x2F;a-small-part-of-6502-chip-expl...</a><p>(I love linking people to this article. It&#x27;s one of my favorite things I&#x27;ve ever read.)