The University of Toronto used to use OS161 as well. The OS161 code contains lots comments, but xv6&#x27;s textbook [1] covers things in more detail which is sometimes useful.<p>[1] <a href="https:&#x2F;&#x2F;pdos.csail.mit.edu&#x2F;6.828&#x2F;2014&#x2F;xv6&#x2F;book-rev8.pdf" rel="nofollow">https:&#x2F;&#x2F;pdos.csail.mit.edu&#x2F;6.828&#x2F;2014&#x2F;xv6&#x2F;book-rev8.pdf</a>