A semiconductor system includes a semiconductor device. The semiconductor device outputs a first group of data and a second group of data to a first group of input/output (I/O) lines and a second group of I/O lines in response to a command and an address. The second semiconductor device sequentially latches the first group of data loaded on the first group of I/O lines and the second group of data loaded on the second group of I/O lines to generate an output data or simultaneously latches the first and second groups of data loaded on the first and second groups of I/O lines to generate the output data, in response to a burst length information signal.