> Brian is super modest and claims to be a horrible programmer but he is comparing himself to Ken Thompson, who he thinks is just incredible. Ken once wrote a disassembler, assembler and B interpreter for a mini-computer that ran a printer they were struggling with, in a couple of days, so that they could get it printing again. This blew Brian's mind.

For the next level up here's Ken (in a very interesting conversation with Brian Kernighan about the history of Unix) describing McIlroy:

> McIlroy keeps coming up. He's the smartest of all of us and the least remembered (or written down)... McIlroy sat there and wrote ---on a piece of paper, now, not on a computer--- TMG [a proprietary yacc-like program] written in TMG... And then! He now has TMG written in TMG, he decided to give his piece of paper to his piece of paper and write down what came out (the code). Which he did. And then he came over to my editor and he typed in his code, assembled it, and (I won't say without error, but with so few errors you'd be astonished) he came up with a TMG compiler, on the PDP-7, written in TMG. And it's the most basic, bare, impressive self-compilation I've ever seen in my life.

This story, by the way, leads into how Ken created B (and how that was eventually improved by Dennis Ritchie into C).

[0] https://youtu.be/EY6q5dv_B-o?t=2314