Abstract: The invention relates to a process for data input and data output into or out of an electronic data processing means that has an input to which a voltage is applied via a resistor and that is connected to the ground via an input switch, so that the voltage present at the input is higher than a specified voltage value when the input switch is open and lower than a specified voltage value when the input switch is closed, which is recognized by the software running in the electronic data processing means so that, by actuating the input switch, data can be input into the electronic data processing means. In a preferred embodiment that has an output line, the data can be input via the output line so that no separate line is needed.