Communications ports The widest application of D-subs is for
RS-232 serial communications. RS-232 devices used the DB-25 as far back as the
Bell 103 modem in 1967 (though the
Teletype Model 33 was the most common ASCII RS-232 device, its signal interface was an internal
Molex connector). The 1969 RS-232-C standard recommended the DB-25 female connectors for DTE and DCE devices, and male-to-male cables to connect them; this was codified in EIA-232D. The timesharing era from the mid-1960s to the early 1980s relied heavily on minicomputers, modems, printers, and video-display terminals connected by DB-25 cables. As the EIA-232 standard improved, many of its defined signals became obsolete. Handshaking and secondary channel pins were not used, making a B-size connector unnecessarily large for two signal wires and ground. Vendors gradually moved away from the DB-25 to the more compact DE-9 for serial communications, and adopted standards other than EIA-232-D. The conventions for use of DB-25 eroded: the original IBM PC, and therefore many compatibles, used a DB-25 male connector at the device and a male-to-female cable to a modem, while using a female DB-25 connector as a
parallel port (instead of the bulkier
Centronics port found on the printer itself). Early
Apple Macintosh models used DE-9 connectors for
RS-422 multi-drop serial interfaces (which can operate as RS-232). Later Macintosh models use 8-pin
miniature DIN connectors instead, while the
IBM PC/AT switched to DE-9M connectors for serial communications. 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. Such usage is not standardized between manufacturers and may require special cables.
Network ports DE-9 connectors were used for some
Token Ring networks as well as other
computer networks. ) and DE-9 (
serial console) connectors. Note the sliding clip on the former. 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 AUI cables used DA-15 connectors albeit with a sliding latch to lock the connectors together instead of the usual hex studs with threaded holes. 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. In vehicles, DE-9 connectors are commonly used in
Controller Area Networks (CAN): female connectors are on the bus while male connectors are on devices.
Computer video output DE-9 connectors 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). Even though these all use the same DE-9 connector, the displays cannot all be interchanged and monitors or video interfaces may be damaged if connected to an incompatible device using the same connector.
DE-15 connectors ,
SVGA and
XGA ports. It is blue per to the
PC System Design Guides color-coding scheme.Later analog video (
VGA and later) adapters generally replaced DE-9 connectors with
DE-15 high-density sockets (though some early VGA devices still used DE-9 connectors). DE-15 connectors have the same shell size as DE-9 connectors (see above). The additional pins of the DE-15 VGA connector were used to add increasingly sophisticated monitor-sensing
plug and play functionality.
DA-15 connectors Many Apple Macintosh models, beginning with the Macintosh II, used DA-15 sockets for analog RGB video out. These connectors had the same number of pins as the above DE-15 connectors, but used the more traditional pin size, pin spacing, and size shell of the DA-15 standard connector. "VGA adapters" (i.e. DA-15 to DE-15 dongles) were available but sometimes monitor-specific, or they needed
DIP switch configuration, as the Macintosh's monitor sense pins in particular were not identical with a VGA connector's
DDC. The earlier
Apple IIGS used the same physical DA-15 connector for the same purpose but with an incompatible
pinout. A digital (and thus also incompatible) RGB adapter for the
Apple IIe also used a DA-15F. The
Apple IIc used a DA-15F for an auxiliary video port which was not RGB but provided the necessary signals to derive RGB.
Game controller ports DE-9 connectors s The 1977
Atari Video Computer System game console uses modified DE-9 connectors (male on the system, female on the cable) for its
game controller connectors. The
Atari joystick ports have bodies entirely of molded plastic without the metal shield, and they omit the pair of fastening screws. In the years following, various video game consoles and
home computers adopted the same connector for their own
game ports, though they were not all interoperable. 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. Some computers supported additional buttons, and on some computers additional devices, such as a
computer mouse, a
light pen, or a
graphics tablet were also supported via the game port. Unlike the basic one-button digital
joysticks and the basic paddles, such devices were not typically interchangeable between different systems. Systems using the DE-9 connector for their game port include the
TI-99/4A,
Atari 8-bit computers,
Atari ST,
Atari 7800,
VIC-20,
Commodore 64,
Commodore 128,
Amiga,
Amstrad CPC (which employs
daisy-chaining when connecting two Amstrad-specific joysticks),
MSX,
X68000,
FM Towns,
ColecoVision,
SG-1000,
Master System,
Mega Drive/Genesis, and the
3DO Interactive Multiplayer. The original
ZX Spectrum lacks a built-in joystick connector of any kind but aftermarket interfaces provided the ability to connect DE-9 joysticks. Later Amstrad branded models included two DE-9 ports but used the proprietary
ZX Interface 2 layout mapped to the number keys.
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 and Bally Astrocade use DE-9 connectors for their detachable joystick as well. Both are incompatible with the Atari connector. Many
Apple II computers also use DE-9 connectors for joysticks, but they have a female port on the computer and a male on the controller, use analog rather than digital sticks, and the pinout is completely unlike that used on the aforementioned systems. DE-9 connectors were not used for game ports on the Macintosh,
Apple III,
IBM PC compatibles, or most game consoles outside the aforementioned examples. Sega switched to proprietary controller ports for the
Saturn and
Dreamcast.
DA-15 connectors DA-15S connectors are used for PC joystick connectors, where each DA-15 connector supports two joysticks each with two analog axes and two buttons. In other words, one DA-15S
game adapter connector has 4 analog potentiometer inputs and 4 digital switch inputs. This interface is strictly input-only, though it does provide +5 V DC power. Some joysticks with more than two axes or more than two buttons use the signals designated for both joysticks. Conversely, Y-adapter cables are available that allow two separate joysticks to be connected to a single DA-15 game adapter port; if a joystick connected to one of these Y-adapters has more than two axes or buttons, only the first two of each will work. 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. The
standard straight game adapter connector (introduced by IBM) has three ground pins and four +5 V power pins, and the MIDI adaptation replaces one of the grounds and one of the +5 V pins, both on the bottom row of pins, with MIDI In and MIDI Out signal pins. (There is no MIDI Thru provided.) Creative Labs introduced this adaptation. The
Neo Geo AES game console also used the DA-15 connector, however, the pins are wired differently and it is therefore not compatible with the regular DA-15 PC game controllers. The
Family Computer console had controllers that were hardwired but also included a DA-15 expansion port for additional peripherals. Many
clones of the hardware used a DA-15 which implemented a subset of the Famicom expansion port and were therefore compatible with some Famicom peripherals. Later clones switched to the cheaper DE-9 port. The
Atari 5200 console also used a DA-15 instead of the DE-9 of its predecessor to facilitate the
matrix for the keypad. The
Atari Falcon,
Atari STe and
Atari Jaguar used a DE-15.
Other 25-pin sockets on Macintosh computers are typically single-ended
SCSI connectors, combining all signal returns into one contact (again in contrast to the Centronics C50 connector typically found on the peripheral, supplying a separate return contact for each signal), while older
Sun hardware uses DD-50 connectors for Fast-SCSI equipment. As SCSI variants from Ultra2 onwards used differential signaling, the Macintosh DB-25 SCSI interface became obsolete. 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. Atari also used this connector on their
16-bit computer range for attaching
hard disk drives and the Atari
laser printer, where it was known as both the ACSI (Atari Computer System Interface) port and the
DMA bus port. 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). In professional audio, several connections use
DB-25 connectors: •
TASCAM and many others are using a connection over DB-25 connectors, which has been standardized into
AES59. This connection transports
AES3 digital audio or analog audio using the same pinout. • TASCAM initially used their
TDIF connection over DB-25 connectors for their
multitrack recording audio equipment. The transported signals are not AES3 compatible. •
Roland used DB-25 connectors for their
multi-track recording audio equipment (
R-BUS). A few
patch panels have been made which have the DB-25 connectors on the back with
phone jacks (or even
TRS phone connectors) on the front, however, these are normally wired for TASCAM, which is more common outside of
broadcasting. In broadcast and professional video,
parallel digital is a
digital video interface that uses DB-25 connectors, per the
SMPTE 274M specification adopted in the late 1990s. The more common
SMPTE 259M serial digital interface (SDI) uses
BNC connectors for digital video signal transfer. 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. The comparatively rare DC-37 connector was also found as the so-called "
GeekPort" electronics experimentation
breakout connector on the even rarer
BeBox computer. DB-25 connectors are commonly used to carry analog signals for beam displacement and color control to laser projectors, as specified in the ISP-DB25 protocol published by the
International Laser Display Association. ==Wire-contact attachment types==