Operating Systems - nimrody/knowledgebase GitHub Wiki

Operating Systems Course
Little book of OS development (and here)
Microsoft Midori
Genod - operating system framework
Helios - ddvaults's microkernel
ZealOS - TempleOS modernized
Board.KolibriOS.org https://kolibrios.org/en/screen.htm
menuetOs https://www.menuetos.net/0983.png