While there is a variety of connectors for PCs, the pin (male) and socket (female) design of the Molex design has become recognized and very common for simplicity, reliability, and low cost.
Molex connector is the vernacular term for a two-piece pin and socket interconnection. Pioneered by Molex Connector Company, the two-piece design became an early electronic standard. Molex developed and patented the first examples of this connector style in the late 1950s and early 1960s. First used in home appliances, other industries soon began designing it into their products from automobiles to vending machines to mini-computers.
In such a connector, cylindrical spring-metal pins fit into cylindrical spring-metal sockets. The pins and sockets are held in a rectangular matrix in a nylon shell. The connector typically has 2 to 24 contacts and is polarized or keyed to ensure correct orientation. Pins and sockets can be arranged in any combination in a single housing, and each housing can be either male or female.
There are three typical pin sizes: 1.57 mm (0.062 in), 2.13 mm (0.084 in), and 2.36 mm (0.093 in). The 1.57 mm pin can carry 5 A of current, while the 2.36 mm can carry 8.5 A. Because the pins have a large contact surface area and fit tightly, these connectors are typically used for power.
In October 1963, AMP (now TE Connectivity) introduced the Mate-n-Lok connector. The AMP connector was similar to the patented Molex connectors but not interchangeable. Both were widely used in the computer industry and the term "Molex connector" is often inaccurately used to refer to all nylon plugs and receptacles.
The first 5.25-inch floppy disk drive, the Shugart SA400, introduced in August 1976, used the AMP Mate-n-Lok connector part number 350211-1. This connector became the standard for 5.25-inch format