Chris Siebenmann is a Unix herder in the Unix systems group here at the University of Toronto along with people such as Paul Kern.
pkern's misc stuff.

UZI180 - Unix Z80 Implementation for the Z-180 (UZI180)

Pyramid Technology
DC/OSx is a discontinued Unix operating system for MIPS based systems developed by Pyramid Technology.
SINIX is a discontinued variant of the Unix operating system from Siemens Nixdorf Informationssysteme.

Stack Overflow - How can I reverse the order of lines in a file?

YouTube - VCF East 2019 -- Brian Kernighan interviews Ken Thompson by Vintage Computer Federation
YouTube - T-Dose 2016, From UNIX to Linux, a time lapse of 45 years, Hendrik Jan Thomassen by CityTV.nl.
YouTube - Jon "maddog" Hall talks Unix and Linux history by Charbax.
YouTube - The Hidden Early History of Unix The Forgotten history of early Unix by FOSDEM.
YouTube - The History of Unix, Rob Pike by Stephanie Borgman.
YouTube - Unearthing the History of Unix: Warner Losh by BSDCan.
YouTube - Unix: History and Memoir by nerdearla.
YouTube - Unix Architecture Evolution from the 1970 PDP-7 to the 2018 FreeBSD Important Milestones and Lesson… by FOSDEM.