Originally developed by the Deutsches Institut fur Normung (DIN), which means the "German Institute for Standardization," the mini-DIN connector is a round plug containing a varying number of pins. The mini-DIN connector has found its way into a number of electronic devices, including computers, peripherals, and video equipment. Mini-DIN connector plugs typically have a symmetrical layout of pins combined with a plastic or metal key which ensures that they can only be connected in the correct way. They are frequently referred to by the name of the specific connection that they carry, such as the PS/2 mouse connector or S-Video connector.
The mini-DIN connector has three features. First, plugs have anywhere from three to nine pins which carry data, power, or a ground signal. Next, every mini-DIN plug has a round metal shield with a diameter of 9.5 millimeters and has certain notches or bumps to ensure that it is only connected correctly. Finally, they all have a non-conductive block that goes into a port on a mini-DIN jack to, again, prevent it from being incorrectly inserted. More than just making the connected devices work, correct insertion also protects the pins in the mini-DIN connector, which are very small and fragile.
One of the best-known mini-DIN connectors is the four-pin variant which is used in the S-Video connection standard. This standard, which came out to support higher quality pre-high definition systems such as S-VHS and the digital video (DV) mini-DV specification. Unlike composite video which carries the entire picture signal on one wire, S-Video separates information by brightness, or luminance, and color, also known as chroma, for better video quality. The four pin connector also came into use in many power supplies as well as in Apple® Desktop Bus (ADB™) peripherals, which was a precursor to the universal serial bus (USB).
When International Business Machines (IBM) released the Personal System/2 (PS/2) series of computers in 1987, they were supposed to return IBM to the top of the personal computer market. Although they failed to accomplish this goal, their small round mouse and keyboard connectors remained a standard for almost 20 years. The PS/2 mouse and keyboard connector uses a six-pin mini-DIN plug.
Beyond these well known applications, the mini-DIN connector is present as a multimedia connector on many notebooks and as a connection between scanners and their accessories, such as page feeders and light-up transparency adaptors. Professional audio and disc jockey components also frequently have this style of plug and jack. Many computer video cards also use mini-DIN jacks as connectors for their proprietary input and output cables.