>> Or 27 resistors going to a single pin held at 2.5v (using an op amp).
>>
Ah.  So THAT'S what an LCD driver actually does in a micro!  Lets the
third state of pins float at a different voltage.  From looking at
the external schematics of such things, it was clear that they were
getting a different voltage level, but I never quite connected that
with THREE possible output voltages...

BillW
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