You can thank reader [Alexandre Novello]’s laziness for generating this hack. Actually, as a self-proclaimed “software guy” he would have never approached this project if it wasn’t for the situation he was in: having to walk across the room to open the door for people, a door which has an electric opener right next to it. He’s got a thorough write-up on how he built the client and server portions of his software in Delphi. He also covers the hardware switch which is attached to the server via parallel port.