I noticed pr #1594, which does what I did only differently wrt aha2[78]4x
support.

I like the thought of having one ahc driver which will support all the
aha* using aic7770 or aic7870.  Is there something broken with that
pr?  I'd consider updating the pr if others agree it's a Good Thing.

This brings up yet another point.  Where should a driver which supports
more than one bus (pci, isa, and eisa) go?  It doesn't fit anywhere
really.  Perhaps the divided bus idea was a bad one, or the divisions
were bad?