I’ve read that Ken wrote the kernel with an eye to it
being a coding exemplar.
Deliberately wrote consistent, high quality code.
From UNIX Implementation:
What is or is not implemented in the kernel represents both a great responsibility and a
great power. It is a soap-box platform on "the way things should be done."
- Ken Thompson, 1977
This paper can be found in the BSTJ Vol. 57, No. 6 as well as various "Documents for
UNIX" compilations such as the Version 7 manual Volume 2.
- Matt G.