D-sub connectors, or d-subminiature connectors is a group of plugs and sockets that are commonly used in the communications area of older PCs. For instance, the analog VGA monitor interface uses a d-subminiature 15-pin plug and socket. D-sub con connectors are also called DB connectors and d-subs. D-sub connectors come in 9, 15, 25, 37, and 50 pin variations. The D-sub designation doesn’t describe the purpose of each line, it defines the physical structure of the connector itself.
Widely used as a printer port for PCs was the female DB-25. When serial ports were still popular on PCs the second serial port was the male DB-25. The male DB-25 is still commonly used for RS-232 communication devices.
The DB-9 male connector otherwise known as the DE-9 was commonly used for the first serial port on older PCs. They were also used on other communication devices.
The DB 15, DA-15 and DE 15 are widely used connectors. The bigger two-row female DA-15 connector is used as the game port on a PC. The smaller three-row connectors is a female high density DE-15 connector that is used for a VGA port.
D-sub connectors are named for their signature d-shaped metal shield. When they were introduced they were some of the smallest connectors that were used on computer systems. D-sub connectors have two or more parallel rows of sockets or pins that are surrounded by a d-shaped metal shield. The part tht has the pin contacts is called the male connector or plug. The part that contains the socket is the female end.
D-sub connectors were invented by ITT Cannon in 1952. They used D as the prefix for numbering the whole series of connectors. The D was followed by A,B,C,D or E to note the shell size. That was followed by the number of pins or sockets on the connector.
Cannon also made combo D-sub connectors with larger contacts instead of some of the normal contacts that were used for high-current, high-voltage or coaxial inserts. One common variation was the DB-13W3. It was commonly used for high-performance video connections.