I did LFS once sometime around 2008. It certainly is an experience, but much of it boils down to downloading a tarball, extracting it, compiling it, then installing it. Then doing that again for 60 other packages. It is a great learning tool, but we invented package managers for this. There is no practical way to keep an LFS system up to date.

Sorry I misread your post. I hung out in an IRC channel some time back. Probably earlier, around 2006-2007. We decided one day we wanted to make an OS from scratch. Personally, I got no farther then fucking around with bootsectors. A BIOS system will load the first 512 bytes from the boot media into memory, and then it is up to that half-kilobyte of code to start the rest of everything. The partition table is also stored in this sector, so you actually get less memory than that.

I managed to write a boot sector which was capable of loading the second sector from a floppy disk into memory (you do this by sending interrupts to the keyboard controller 🙃) , as well as one which would draw a bunch of lines on the screen. That is about as far as I got.

All x86 processors (including modern ones) boot in 16 bit real mode. DOS shit. The UEFI firmware takes the responsibility of transferring the machine into 64 bit protected mode and loading an ELF image, but if you are booting from BIOS, this is also a thing you need to do from scratch. You basically get maybe 300 bytes to write a minimally functional filesystem driver and disk IO layer. On the bright side, the opcodes and pointers are only 16 bits long.

At the time I was fucking around with this, you could order print (and delivered to your door) x86 architecture manuals from Intel at no charge. I was 16 and was able to order them without even having a credit card number. The manuals spanned 5 volumes, and two of them were dedicated to just the instruction set alone.

Under communism, all CISC CPUs will be destroyed and their creators will be sent to the gulag.