Apparatus include a data bus and a signal driver circuit having pluralities of first and second termination devices connected in parallel between a voltage node and an output node. Each of the termination devices is configured to be deactivated in response to control signals having a particular set of logic levels, and to be activated in response to control signals having a set of logic levels other than the particular set of logic levels. Activated second termination devices each exhibit respective resistances greater than a particular resistance of each activated first termination device. Methods include connecting a node of an apparatus to a first voltage node through a reference resistance, connecting the node to a second voltage node through a termination device, and comparing a resulting voltage level to a reference voltage different than half-way between voltage levels of the first and second voltage nodes.