A DRAM device includes first terminals, second terminals, third terminals, a control signal generator, a CRC unit, a row decoder, a column decoder, and a memory cell array. The control signal generator generates a control signal. The CRC unit performs a first CRC logical operation on a first data group including qn-bit first data generated by inputting n-bit first data q times, generates a first CRC result signal, performs a second CRC logical operation on a second data group including qn-bit second data by inputting n-bit second q times, generates a second CRC result signal, and generates an error signal based on the first CRC result signal and the second CRC result signal. The error signal is generated based on the second CRC result signal regardless of the first CRC result signal in response to the control signal.