Honestly here's how you do e.g. ARM: - Get multitasking working in x86 since there are a ton of guides for that. Learn OSdev concepts. - Read the ARMARM. It's

Honestly here's how you do e.g. ARM: - Get multitasking working in x86 since there are a ton of guides for that. Learn OSdev concepts. - Read the ARMARM. It's many thousands of pages of dense technical material, nearly everything you need to get started. The only parts it doesn't cover are boot media/formats and peripherals. There aren't good resources for ARM osdev because the environment is not standardized at all. ARM chips are used everywhere and you're often targeting specific boards, not chips. Writing the ARM-specific stuff is only half the battle.