Efforts to register mental patients and residents of centers for the developmentally disabled have taken place in recent months in several locations around the state.Employees of the Murdoch Developmental Center, a state-run facility in Butner for the mentally retarded and developmentally disabled, recently registered 36 of the more than 500 residents to vote in what appears to have been a voter registration drive at the facility. In addition, some residents were checked out of the facility and transported to early voting centers to cast votes.