The macbook macbook pro and macbook air each have a mini displayport that allows you to connect an external display or projector using an adapter you can use an external display as your main workspace or to extend your desktop or you can work in mirrored mode with a projector so you can view what your audience sees use the mini displayport to dual link dvi adapter to connect your macbook macbook pro or macbook air to a 30 inch display such as the 30 inch apple cinema display hd and e