> > Unfortunately some old BIOSes have the annoying property that they
> > refuse to boot without something looking like a keyboard attached;
> > as witnessed by the infamous "No Keyboard, press F2 to continue"
> > error message (or variants thereof).  Your mileage may wary.
change in BIOS settings (standard options):

Halt on: "all errors" to halt on "all but disk/key" or "no errors"

it well make some beeps etc. but boots without keyboard and graphics... 
> Yes, I suppose.  (I also have a somewhat newer machine that won't boot
> without a video card in it---and there's no BIOS option to override that
see above :)

works