A semiconductor system includes a first semiconductor device and a second semiconductor device. The first semiconductor device outputs an external command and external addresses. The second semiconductor device generates an internal active command in response to the external command, generates active addresses in response to the external addresses, generates a refresh signal and refresh addresses in response to the internal active command, performs an internal operation in response to the internal active command and the active addresses, and performs a refresh operation in response to the refresh signal and the refresh addresses.