>Let me clarify. The process of the MBR bootstrapping the netbsd system and
>the kernel.

You should really get rid of "MBR", because NetBSD doesn't require an
MBR to boot, even on the i386.

What happens in a general sort of way is that the BIOS looks at a special
spot on the disk to find the boot block.  It loads this boot block into
memory and executes it.

The boot block is something that's a little smarter than the BIOS.  It
knows something about the operating system that it's going to boot.  In
the case of NetBSD, the NetBSD boot block knows how to search the root
filesystem on the disk, open up a particular file (in this case, "netbsd"),
load it, and execute it.  Then the kernel starts running, and normal
Unix things start to happen.

Obviously I'm skipping a lot of things here (the kernel has to do a lot
of bootstrapping for itself at first), but that's the general sort of
things that happen: Hardware loads the boot block, the boot block loads
the kernel.  If you want more specifics, you can look at the boot blocks
(/sys/arch/i386/stand).

--Ken