CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

1.5. Standard External Cables

External cables are used on the outside of the computer to connect peripheral devices. The most commonly used connector on external cables is the D-shell connector (named for its shape), which is usually called DB. Looking at the connector with the D pointing toward the ground, pin numbering on male connectors starts with the top-left connector. With the connector in this orientation, the upper-left pin is pin 1, and the order goes across the connector and left to right for all subsequent rows. For a female receptor, hole 1 or pin 1 is in the top-right of the connector if the D is pointing down; other pins are numbered right to left. This allows pin 1 on a male connector to match pin 1 on a female connector. This section covers the three most common cables.

1.5.1. Parallel cable

A parallel cable has a male DB-25 connector on the end that connects to your computer, and a male Centronics 36 connector on the end that connects to the printer. This style of cable is a standard parallel cable or an IEEE 1284 bidirectional cable. If the cable is the latter, you should expect to see IEEE 1284 labeled on the cable or connector.

In addition to this cable, you might also see a parallel extension cable, which will have a male BD-25 connector to attach to your computer and a female DB-25 connector to attach to a parallel printer cable. This cable can easily be confused with a serial cable for a computer with a 25-pin serial connector. The only way to positively ...