thanks Carlos Fenollosa and Anton Burtsev
https://github.com/cfenollosa/os-tutorial/
http://www.jamesmolloy.co.uk/
Writing a Simple Operating System from Scratch Nick Blundell
https://wiki.osdev.org/
https://users.cs.utah.edu/~aburtsev/238P
https://read.seas.harvard.edu/cs161/2022/schedule/
INTEL 80386 programmer's reference manual 1986
http://littleosbook.github.io/
INTEL 64 and IA-32 architectures software developer's manual
https://github.com/dreamos82/Dreamos64
https://github.com/szhou42/osdev