D-subminiature
A D-sub contains two or more parallel rows of pins or sockets usually surrounded by a D-shaped metal shield, or shell, that provides mechanical support, ensures correct orientation, and may screen against electromagnetic interference.
Later D-sub connectors added extra pins to the original shell sizes, and their names follow the same pattern.
For example, the DE-15, usually found in VGA cables, has 15 pins in three rows, all surrounded by an E size shell.
[1] The double density series of D-sub connectors features even denser arrangements and consists of the DE-19, DA-31, DB-52, DC-79, and DD-100.
The non-standard 23-pin D-sub connectors for external floppy drives and video output on most of the Amiga computers are usually labeled DB-23, even though their shell size is two pins smaller than ordinary DB sockets.
Smaller connectors have been derived from the D-sub including the microminiature D (micro-D) and nanominiature D (nano-D) which are trademarks of ITT Cannon.
[12]The widest application of D-subs is for RS-232 serial communications, though the standard did not make this connector mandatory.
Early Apple Macintosh models used DE-9 connectors for RS-422 multi-drop serial interfaces (which can operate as RS-232).
Many uninterruptible power supply units have a DE-9F connector on them in order to signal to the attached computer via an RS-232 interface.
Often these do not send data serially to the computer but instead use the handshaking control lines to indicate low battery, power failure, or other conditions.
Originally in the 1980s Ethernet network interface cards or devices were connected using Attachment Unit Interface (AUI) cables to Medium Attachment Units that then connected to 10BASE5 and later 10BASE2 or 10BASE-T network cabling.
The sliding latch was intended to be quicker to engage and disengage and to work in places where jackscrews could not be used for reasons of component shape.
[13] A female 9-pin connector on an IBM compatible personal computer may be a digital RGBI video display output such as MDA, Hercules, CGA, or EGA (rarely VGA or others).
The additional pins of the DE-15 VGA connector were used to add increasingly sophisticated monitor-sensing plug and play functionality.
The Atari joystick ports have bodies entirely of molded plastic without the metal shield, and they omit the pair of fastening screws.
The most common wiring supported five connections for discrete signals (five switches, for up, down, left, and right movement, and a fire button), plus one pair of 100 kΩ potentiometers, or paddles, for analog input.
NEC's home computers (e.g. PC-88, PC-98) also used DE-9 connectors for game controllers, depending on the sound card used.
The Fairchild Channel F System II[22] and Bally Astrocade[23] use DE-9 connectors for their detachable joystick as well.
The IBM DA-15 PC game connector has been modified to add a (usually MPU-401 compatible) MIDI interface, and this is often implemented in the game connectors on third-party sound cards, for example, the Sound Blaster line from Creative Labs.
D-subminiature connectors are often used in industrial products, the DA-15 version being commonly used on rotary and linear encoders.
The early Macintosh and late Apple II computers used a non-standard 19-pin D-sub for connecting external floppy disk drives.
The Commodore Amiga used an equally non-standard 23-pin version for both its video output (male) and its port for daisy-chaining up to three extra external floppy disk drives (female).
DC-37 connectors are commonly used in hospital facilities as an interface between hospital beds and nurse call systems, allowing for the connection and signaling of Nurse Call, Bed Exit, and Cord out including TV entertainment and lighting controls.
