  We numerically studied the required conditions for achieving a memory
operation based on Kerr bistability in the presence of the thermo-optic effect
in silicon nitride microring cavity systems. By comparing a side-coupled system
and an add-drop system, we found that the latter is needed to realize obtain
Kerr bistable operation. In addition, we show the coupling coefficient range in
which the memory operation does not suffer from the thermo-optic effect.
