How do I build my Own Operating System by just using Assembler and NOT Win?

Hi!
I’m working and researching Operating Systems (OS), but I really want to build my own from scratch without Microsoft Components or Linux COM files.

Is there tools which could compile 16-bit files and let me build an BOOT and OS-loader.

Could somebody tell me where I could find the tools which I need, Pleas! NO VIRUS TOOLS OR TOOLS WHICH ARE CRACK.

Also is there any video tutorials here at Techrepublic where I could learn more about how to build and understand a BIOS.