Adam Davis wrote:

> Use a resister ladder and two pins.  You'll need to have a chip with
> schotky(sp) input, and you'll need to know the cutoff voltage for it.

  Basically, one resistor between two pins.  The second can be an output
that is not otherwise used at the moment of testing (but may have
another output allocation).

  If the input follows the alternate states of the output, it is
connected to a tri-state, if it doesn't it is fixed.  I suspect that is
what was asked for.
--
  Cheers,
        Paul B.