They&#x27;re huge because they have to support a lot of stuff from hardware devices to synthesis to verification. Probably legacy issues in there too. It doesn&#x27;t help that every part of hardware development is Mega-Hard:<p><a href="http:&#x2F;&#x2F;fpgacomputing.blogspot.com&#x2F;2008&#x2F;08&#x2F;megahard-corp-open-source-eda-as.html" rel="nofollow">http:&#x2F;&#x2F;fpgacomputing.blogspot.com&#x2F;2008&#x2F;08&#x2F;megahard-corp-open...</a><p>Each aspect of synthesis, equivalence checking, testing, etc has whole MS&#x27;s and PhD&#x27;s dedicated to it. I&#x27;m sure the result can be a lot smaller than 20GB but it&#x27;s still going to be incomprehensible by one person except in pieces. And that person has to be an expert on every aspect of hardware development from digital to analog to the wires that make up the gates. Like major OS&#x27;s or software, you&#x27;re always going to be taking someone else&#x27;s word that a huge chunk of it&#x27;s safe. Might as well plan around that.