I haven&#x27;t watched through the whole thing, but the C code I saw from skipping through looks like it&#x27;s actually the output from CWEB [1], one of Knuth&#x27;s literate programming tools.  It combines C source code with long-form documentation, and it can either be preprocessed to TeX (to give that nice, pretty printed document that Knuth shows in the video) or to standard C source code to compile and run.<p>CWEB is one of Knuth&#x27;s languages of choice, and he&#x27;s got tons of code written in it on his website [2], including versions of some of the stuff he&#x27;s demoing on-screen.<p>[1] <a href="http:&#x2F;&#x2F;www-cs-faculty.stanford.edu&#x2F;~uno&#x2F;cweb.html" rel="nofollow">http:&#x2F;&#x2F;www-cs-faculty.stanford.edu&#x2F;~uno&#x2F;cweb.html</a><p>[2] <a href="http:&#x2F;&#x2F;www-cs-faculty.stanford.edu&#x2F;~uno&#x2F;programs.html" rel="nofollow">http:&#x2F;&#x2F;www-cs-faculty.stanford.edu&#x2F;~uno&#x2F;programs.html</a>