Ribbon cable

A ribbon cable (also known as multi-wire planar cable) is a cable with many conducting wires running parallel to each other on the same flat plane. As a result the cable is wide and flat. Its name comes from its resemblance to a piece of ribbon.

Ribbon cables are usually seen for internal peripherals in computers, such as hard drives, CD drives and floppy drives. On some older computer systems (such as the BBC Micro and Apple II series) they were used for external connections as well. The ribbon-like shape interferes with computer cooling by disrupting airflow within the case and also makes the cables awkward to handle, especially when there are a lot of them; as a result, round cables have almost entirely replaced ribbon cables for external connections and are increasingly being used internally as well.

The ribbon cable was invented in 1956 by Cicoil Corporation, a company based in Chatsworth, California. The company's engineers figured out how to use a new material, silicone rubber, to 'mold' a flat cable containing multiple conductors of the same size. Since the cable looked like a flat ribbon or tape, it was named a ribbon cable. The ribbon cable allowed companies like IBM and Sperry/Univac to replace bulky, stiff round cables with sleek, flexible ribbon cables.

The early ribbon cables were used in the mainframe computer industry, on card readers, card punching machines, and tape machines. Subsequently ribbon cables were manufactured by a number of different companies, including 3M. Methods and materials were developed to simplify and reduce the cost of ribbon cables, by standardizing the design and spacing of the wires, and the thickness of the insulation, so that they could be easily terminated through the use of insulation displacement connectors (IDC). The simplicity of the cables, their low profile (compared to contemporary alternatives), and low cost due to standardization, meant ribbon cables were long used in computers, printers, and many electronic devices before getting phased out after the turn of the century.

To reduce the risk of reversed connections—which could potentially damage hardware—either when making a cable or when using a cable with unpolarized connectors, one edge of the cable is usually marked with a red stripe. By convention the edge with the stripe is connected to pin 1 on the connector. This method of identification is fine for cables that just consist of two or more IDC connectors with every connector connecting to every wire, but is somewhat less helpful when individual wires or small groups of wires must be terminated separately.

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Wikipedia