This is a bit of a hack, as-is, since there's a lot of code that's
outright duplicated between the various files and because it doesn't
support detection of a network device as the root device. The
latter's not a problem yet, because NetBSD/Alpha can't load the kernel
from the network to begin with.
Support for AXPpci CPUs,
Support for AlphaStation 600 CPUs,
new boot block structure, which requires an 'installboot'
program and works a lot like the NetBSD/sparc boot blocks.
