alpha_cpu.h, and this file is no longer necessary for the
Alpha. However, some machine-independent code (e.g.
/sys/compat/common/kern_exit_43.c) still wants a file with
this name to be around.
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.