Semiconductor systems are provided. The semiconductor system may include a controller and a semiconductor device. The controller may generate command signals and address signals. The semiconductor device may discharge electric charges of a first local line pair and a second local line pair during a predetermined period after a read operation begins according to a combination of the command signals, equalize and pre-charge levels of the first and second local line pairs when a pre-charge operation is executed or the address signals are inputted thereto. The semiconductor device may also sense and amplify data loaded on the first or second local line pair to output the amplified data through an input/output line after the read operation begins.