Excessive theory is worse than no theory because it makes things seem more difficult than they really are. - How to create an OS from scratch

• Writing a “bare metal” operating system for Raspberry Pi 4

• SerenityOS / Andreas Kling - a graphical Unix-like OS for x86, with 90s aesthetics

• I wrote a display server, a desktop environment, and a debugging/reversing tool

• Xv6, a simple Unix-like teaching operating system / HN

• minix 3 - Deader than disco.