mov dx, 200
mov ah, 9
mov ax, 4c00
db "Hello, World$"
Edit: Geezus. It's just an example of how accessible getting something running in assembly language was compared to all the qemu, UEFI stuff in the article.
A BIOS CALL. :)
Still not bare metal.
(I'm totally gatekeeping for laughs: write your own BIOS you noob!)
You can still use INT 10 for BIOS video services.
Or just write into the text framebuffer directly; it's at B800:0000 in colour modes and B000:0000 in monochrome modes (it's surprising how much I still remember from when I exclusively did x86 PC Asm, ~3 decades ago.)
It look liked this 1200 page book, but this isn't it (also a book I used):
I also had the Apple ][+ ROM listing in one of those spiral-bound books from apple circa 1980 but that too has been lost, sadly.
https://sites.google.com/site/pcdosretro/ibmpcbios has the source code for various models typed.
I'm not sure it would work if you stuck this in a boot sector.
 Why do I even remember this stuff? I haven't used any of this since the early 90s! Sheesh!
IIRC, BIOS was 10 and 13.