Computer Ports and Connectors

Computer Ports and Connectors

This hub will describe the nature of each of the main external Computer ports, their connector types and common usage. A port is a connector at the back of a computer where you plug in an external device such as a printer, keyboard, scanner, modem etc. This allows instructions and data to flow between the computer and the device.The computer ports are also commonly referred to as the Input/Output ports (I/O ports).

Most connectors are polarized, permitting the cable to be plugged in only in the correct direction. The keyboard and mouse use "PS2" connectors. The PS2 connectors are color-coded. The purple connector is for the keyboard. The green connector is for the mouse.

Note: The PS2 type connector was invented by IBM for their model PS2 computers.

To plug in a keyboard or mouse cable, first match the cable to the connector. Rotate the cable until the connector keys match up. Then push the cable into the connector. Be sure not to force the connector because you will end up bending the pins.

The parallel port, serial port, and video port all use "D" type connectors (DB-25M, DB-9M and DB-15F respectively). These are called D connectors because of their shape, which permits the cables to be plugged in only one way.

The serial port was originally used for the mouse and modem, but it was a real pain to configure those ports. The serial port is now obsolete. The parallel port is almost obsolete, although it is still required by some printers. Both of these ports have been replaced by the USB (Universal Serial Bus) port. A USB port is keyed so that a USB cable can be plugged in only one way.

The audio jacks are the most confusing connectors on the back panel. Although the jacks are sometimes color-coded, the devices that plug into them rarely are.

The green jack (audio out) is where you plug in your left speaker. The right speaker plugs into a jack on the left speaker. The red jack is where you plug in your microphone. The center jack (audio in) is where you plug in audio from another device, such a CD player.

Note: The audio jacks have identifying symbols stamped into the metal next to them.

A computer cable connector is the part of a cable that plugs into a port or interface to connect a device to the motherboard or to another device. Most connectors are either male (containing one or more exposed pins) or female (containing holes in which the male connector can be inserted). A number of different connector types are used to connect various external devices to the computer.

DB Connectors

This connector type is most often associated with the serial, parallel and display monitor ports. DB stands for ‘D Bucket’ connector and the full connector designation e.g. DB25 male refers to the number of pins in the connector and whether the connector is male (plug) or female (socket) type.

NB: If a DB-type port uses a female connector, the cable associated with the port will require a male connector to ‘mate’ correctly and vice versa.

The standard 15-pin VGA connector was derived from an older 9-pin design; consequently the plugs have 15 pins in a connector shell originally designed for 9. The only way to make more pins fit was to make them thinner; this also makes them more prone to bending so always take care when plugging in video leads because bent pins are hard to straighten without them breaking off.

The DIN connectors

Another type of connector we have is the DIN connector - DIN is an abbreviation for Deutsches Institut für Normung, or German Institute for Standardization, which is a German manufacturing industry standards group. DIN connectors are round, with pins arranged in a circular pattern. This type of connector was used widely for PC keyboards, MIDI instruments, and other specialized equipment.

We have two types of DIN, Full DIN and Mini DIN.

Full DIN or five pin DIN

The 5-pin Din connector has 5 pins that are arranged in a circular pattern. This type of connector was commonly used for older AT-style computer keyboards which are obsolete nowadays.

Mini DIN

The 6-Pin Mini Din has 6 pins as well as a keying block. This interface was first used on the IBM PS/2 personal computer. For this reason the connector is often called a PS/2 connector. This connector has become the industry standard for connecting keyboards and mice.

Audio Connectors

Most of the audio connectors on a PC are 3.5mm mono and stereo jack plugs as used on most portable domestic audio equipment.