There is also some useful discussion of technique for a master/slave
two-headed VAX 11/780 running 4.1 (and later 4.2) BSD UNIX in a paper by
George Goble, which can be found at

http://ghg.ecn.purdue.edu/

in a series of GIF files (I guess he lost the original [nt]roff source).
You can also look at the interesting photos of George lighting a BBQ grill
with LOX (and I don't mean smoked fish).

        Erik Fair