I know the title reeks of confusion, and some of you might assume I am just wondering about how the computer boots in general, but I'm not. But I'll sort this out for you people now:

1.Onboard firmware is how mostly all modern computer devices work, whether or not with EFI/UEFI(even without "onboard firmware", older computers still employed bank switching, or similar methods with snap-in firmware, cartridges, etc.)

2.On startup there is no "programs" running in the traditional sense yet, i.e. no kernel, OS, user-applications; all of the instructions, especially the very first instruction, is specified by the Instruction Pointer, I am guessing. How is the IP/PC/etc. set to first point to an address for a BIOS/firmware/etc. instruction, and how do the BIOS instructions map themself out in memory prior to startup?

3.Aside from MMIO, BIOS uses certain RAM addresses to have instructions. The big ? comes in when I ask this ... how does BIOS do this?

Conclusion:

I am assuming that with the very first instruction there is an initial hardware setup for BIOS prior to complete OS bootup. What I want to know is if it's hardware engineered to always work this way, if there's another step in this bootup method I am missing, a gap of information I am unaware of, or how this all works from the very first instruction, and the RAM data itself.