An apparatus includes a first external terminal, a first circuit, a signal line and a second circuit. The first external terminal receives at least one of data mask information and data bus inversion information. The first circuit performs one of an error check operation and a data bus inversion operation. The signal line is coupled between the first external terminal and the first circuit. The second circuit is coupled to the signal line and first a voltage level of the signal line at a substantially constant level responsive to a first control signal.