I think the one thing we've lost is the complete "down to the register" accessibility and the close coupling of hardware and software. You can write your own b

I think the one thing we've lost is the complete "down to the register" accessibility and the close coupling of hardware and software. You can write your own boot code from bare metal and actually make useful things happen based on data sheets. It's concievable to grasp an entire 8086 or 68000 system in that way, but the Raspberry Pi, for all its benefits, is almost certainly going to be dealt with with relatively high-level languages and abstractions.