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As a first requirement, your code must execute in an enviroment that grants direct hardware access, either in real mode or in protectec mode with supervisor (kernel) privileges.
Then you have to write your own drivers respectively BIOS. You should however consider, that a video card supplies it's own BIOS as a wrapper for direct hardware access. If you don't use it, you have to know all specific hardware details of your video card. Also modern PC hardware has a lot of chipset specific properties, that would be hard to control without the built-in BIOS.
You have a fair chance, if you start with old XT or AT boards, that uses exclusively standard hardware with wellknown addresses and register function.