If you can find a copy of this on the high seas, it's a great resource. I wrote my own OS by starting with this and the Linux source in the mid-90s:

https://www.amazon.com/-/he/Developing-32-Bit-Operating-Syst...

Ha! Same. Lost the code too. It was fun actually booting something into bare metal. This book helped a lot:

https://www.amazon.com/Developing-32-Bit-Operating-System-Cd...

I always drop this book when people talk about writing or hacking their own OS etc:

https://www.amazon.com/Developing-32-Bit-Operating-System-Cd...

Can probably find it on a shadow library. Getting something to boot on x86 is a little tricky, because IIRC the CPU comes up in real mode, so you have to create your own boot sector and bootloader before you can even execute your kernel.

That book + Linux inspired me to write my own OS in 1995. My goal was to have an OS that booted directly into a modern GUI and fitted (with basic tools) onto a single 1.4Mb floppy, which I did manage.

This is a really good step-by-step reference to writing your own OS:

https://www.amazon.com/Developing-32-Bit-Operating-System-Cd...

Find a copy on your favorite shadow library.

I did the same in the mid-90s but for a 32-bit hobby GUI OS. This book was absolutely essential reading:

https://www.amazon.com/Developing-32-Bit-Operating-System-Cd...

Having checked off most of the list, I would agree the Game Boy emulator is far easier than the OS.

I guess with the emulator it depends how much you want to do. You'd be foolish to write a console emulator and not import someone else's CPU code. When I wrote a Game Gear emulator 26 years ago I used off-the-shelf CPU code and just mapped all the in/out and did the graphics bits. Took me and a friend a single evening to get it happily playing games.

And OS is harder. Well, it was last time I wrote one, again about 26 or 27 years ago. Getting something to boot at all was tricky. I used this book as my main source of inspiration:

https://www.amazon.com/Developing-32-Bit-Operating-System-Cd...

After I started using Linux in 1994 I wanted to write my own OS that was entirely GUI based. I used this book to learn the fundamentals and it really would help explain a lot of the Linux code, and would also teach you how to even get your kernel loaded and booted, which is the hardest bit for a new OS:

https://www.amazon.com/Developing-32-Bit-Operating-System-Cd...

It's funny - I remember doing pretty much the same thing. I wrote my own GUI OS from scratch in x86 based partially on the following book, in about 1998: https://www.amazon.com/Developing-32-Bit-Operating-System-Cd...

And then wrote my own Game Gear emulator for it one night, just for shits and giggles, like you did. It was also my first attempt at writing a whole system emulator, and the GG, like the GB, was incredibly well understood even back then.

For anyone interested in emulation I think it is a great little project to write a video game emulator. It is enormously fun to watch one of your favorite video games boot up in code that you wrote. And it is fun (for me) to try and debug all the little glitches where you've made errors or omissions in your emulator.

This is the book I learned from in the 90s: https://www.amazon.com/Developing-32-Bit-Operating-System-Cd...

It's basically "Writing an Operating System from Scratch for Dummies".

I actually wrote my own graphical x86 OS starting from the code in there.

Related: Source Code For MMURTL:

https://github.com/bproctor/MMURTL

Keywords: Richard A. Burgess "Developing your own 32-bit operating system"

Buy either of his two books on Amazon:

https://www.amazon.com/gp/product/0672306557

https://www.amazon.com/gp/product/1588530000

I remember this as a great book on OS'es, back in the day...

Back in the 90s they used to do these quite often. I remember reading one for the same reasons, self taught network engineer and programmer and wanted to get under the hood. I say do it and bring the concept upto date.

Here's an examplehttp://www.amazon.com/Developing-32-Bit-Operating-System-Cd-...