What is the function of the keeper circuits?
The keepers are intended to keep nets from oscillating while not being actively driven. They are not intended to keep a certain logic level on a net. They supply a small (less than 100uA) drive current that works to maintain the net in its current state. The keepers do not force the level of the net to a particular value, so they do not take the place of required pullup or pulldown resistors.
