Nelson H. F. Beebe writes:
Jon Steinhart writes
I use UNIX instead of Unix as that's what I
believe is the correct form.
Brian Kernighan addresses this issue in section 7.3 of his
recent memoir: it has "UNIX A History and a Memoir" on the
cover, but prefers "Unix" in the rest of that book, except
in the noted section. He also refers back to the 1984
book with Rob Pike, "The UNIX Programming Environment",
in which the typography uses small caps for "UNIX".