I want to say thank you to all who answered my request, both
privately and on the list.  I tried the URL's suggested and found every bit
of the information I needed.  It looks like the game port connector is another
four-bit input although there is no strobe or hand-shake lines as such.
One of the web sites mentioned that one could sample the current drawn by
the timing capacitors in the analog inputs which are reset each time one
writes to the port so there is a kind of output possibility if one isn't
too picky about wave forms.  All timers are started at once so there
is really only one output available.

        The other thing that I thought of is that if one has an older system
that has the unidirectional printer port, a game port could give you the
other four bits that are not available on the printer port which does have
strobe capabilities.  One would just have to read the four bits from the
printer port, four bits from the game port and combine them.  I haven't
tried this, but there isn't anything extraordinary about reading the game
port digital lines.

        Again, thanks to all.

Martin McCormick