However, some rationalization of the machine specific commands is probably
   in order (sparc says "prom" when everyone else uses "halt"). Now that
   they're all documented side-by-side, comparisons can be made.


please note these are two different commands.  'halt' means to end
the execution of the operating system, where as the sparc "mach prom"
just drops you back to the prom, but the OS is still running, you
just have to "go" (c for old proms) to continue the OS...


this distinction (ability of the sparc) is very useful... i'd like
to eventually write, eg, a ps(1) type util in forth for it, etc...
nice for debugging  :)