The Mini-DVI connector is used on Apple computers as a digital alternative to the Mini-VGA connector. Its size is between the full-sized DVI and the tiny Micro-DVI. It is found on the 12-inch PowerBook G4, Intel-based iMac, the MacBook Intel-based laptop, and the Intel-based Xserve, but not the MacBook Air, which uses Micro-DVI instead. Mini-DVI connectors on Apple hardware are capable of carrying DVI, VGA, or TV signals through the use of adapters, detected with EDID (Extended display identification data) via DDC. This connector is often used in place of a DVI connector in order to save physical space on devices. It needs a Mini-DVI Adapter to connect to another monitor. Mini-DVI does not support dual-link connections and hence cannot support resolutions higher than 1920x1200 @60Hz.
There are various types of Mini-DVI Adapter:
The physical connector is similar to Mini-VGA, but is differentiated by having four rows of pins arranged in two vertically-stacked slots rather than the two rows of pins in the Mini-VGA.
To use a DVI-I connecter, you must connect a Mini-DVI to DVI-D cable to a DVI-D to DVI-I adapter.