A semiconductor system includes a first semiconductor device and a second semiconductor device. The first semiconductor device outputs command/address signals and a plurality of data. The second semiconductor device generates a first mode signal and a second mode signal according to a combination of the command/address signals. The second semiconductor device is suitable for inverting the plurality of data inputted through a pad in response to the first or the second mode signal to store the inverted data suitable for blocking input of the inverted data in response to the second mode signal if a number of bits having a predetermined level in the plurality of data is equal to or greater than a predetermined number.