Voters Education The Control Unit is the control section of the EVM and it is only operated by the polling official. This unit controls the polling process. The Control Unit consists of four sections, the display screen, candidate set, results and ballot button. Voting using the EVM The EVM does not change the existing voting pattern but only replaces the issuing of a paper ballot by the press of a green button on the Control Unit and instead of the voter marking or making a cross on the ballot paper, he/she will be pressing a green button corresponding to the political party or candidate of his or her choice. The voter then has to press the red Register button on the Ballot Unit to complete the voting process.