2^x bit operating system development

Question

I don't know how silly is my question although Its to interesting for me! I did a little investigation about os development and I found that all of tutorials are developing 32 bit os(x86 isn't 32 bit? )
So I have a question, what are differences between 32 and 64 or 16 bit operating system development process? Can you start developing OS only 64bit or you need to make 32 bit first and build 64 on top of it?

Answer 1

The x bit defines the size of registers, memory addresses, etc. When your computer boots up it boots in real mode or 16 bit mode for compatibility reasons. Then you can further escalate to 32 or 64 bit if the hardware supports it.