I have a 5 1/4" drive as drive A.  How can I make the system boot from
my 3 1/2" B drive?  (Optimally, the computer would be able to boot
from either A or B, checking them in order for a bootable disk.  But
if I have to switch cables around and simply switch the drives so that
it can't boot 5 1/4" disks, that's OK.  Also, boot_b won't do the trick
for me.)

Thanks,
  Davebo
