initial device, and will also allow for e.g. a device menu to be presented
to the user.

Change from using #if to #ifdef, since #if can't cope with string
constants.

Move ISA probe address logic from config.c into isa.c, create header file
config/isa.h.

link time to accommodate whatever bus objects are included.

the boot device.

*other* than the main boot device.

Tie into new boot device framework.

out the new probing logic.

infrastructure.

call it initialise() and place it in main.c.  :)

only via the initialisation function table.

logic (e.g. avoiding memory regions with A20=0).