COMPUTER CABLES

Computer Cables

Computer cable, also known as a cord, is one or more wires covered in a plastic covering that connects a computer to a power source or other device. They are used for communication and to send signals between connected devices. There are two main types of computer cables, namely:

a.       Power Cables – These are used to supply electricity to the computer system. A power cable consists of two or more electrical conductors usually held together with an overall sheath.

 

b.      Data Cables – These are cables that provides communication between devices. They allow baseband transmissions (binary 1, 0’s) from a transmitter to a receiver. There are various types of data cables. Their classification depends on the type of data transmitted and the destination port of the receiver. Examples are printer cable, Universal Serial Bus (USB), monitor cable, serial cable.

i.    Printer Cable – This carries data between a computer and a printer. There are many different types of printer cables such as Serial, Parallel, FireWire, USB.

ii.   Monitor Cable – This, also called VGA (Video Graphics Adapter) is a three-row 15-pin DB-15 connector. The 15-pin VGA connector is found on many video cards, computer monitors, and some high definition television sets. On laptop computers or other small devices, a mini-VGA port is sometimes used in place of the full-sized VGA connector. VGA connectors and cables carry analog component RGBHV (Red, Green, Blue Horizontal Sync Vertical Sync) video signals, and VESA DDC (VESA Display Data Channel) data. The monitor can be connected via VGA or DVI or HDMI connector.

iii.  Serial Cable – This cable can be used to transfer information between two devices using serial communication. The form of connectors depends on the particular physical layer used.

A cable wired for connecting two DTEs (Data Terminal Equipment) directly is known as a null modem cable. An example of a serial cable is monitor or VGA cable.

iv.  IDE/ATA/PATA – Integrated Drives Electronics/AT Attachment/Parallel ATA is an interface standard for the connection of storage devices such as hard disk drives, floppy disk drives and optical disc drives in computers.

v.   SATA – Serial AT Attachment is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives and solid-state drives. This succeeded the older Parallel ATA standard, offering several advantages over the older interface; reduced cable size and cost (seven conductors instead of 40 or 80), native hot swapping, faster data transfer through higher signaling rates, and more efficient transfer through an (optional) I/O queuing protocol.

iv.  Network Cables – Network cables are used to connect and transfer data between computers and a network. There are different types of network cable. These cables are used depending on the structure and topology of a network. The most commonly used types of network cables are:

Twisted Pair – This cabling is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of cancelling out electromagnetic interface (EMI) from external sources. Twisted pair cables were invented by Alexander Graham Bell in 1881.

Twisted pair cables are mainly used for Ethernet networks and telephone lines.

There are two types of twisted pair cables, namely: unshielded twisted pair and shielded twisted pair. A shielded twisted pair has a material covering the wires to prevent electromagnetic interference. 

Coaxial Cable – This is an electrical cable with an inner conductor surrounded by a flexible tubular insulating layer surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis. Coaxial cable was invented by English engineer and mathematician Oliver Heaviside.

Coaxial cable is used as a transmission line for radio frequency signals. Its applications include feedlines connecting radio transmitters and receivers with their antennas, computer network connections, digital audio, and distributing cable television signals. 

Optical Fiber Cable – This is a technology that uses glass or plastic threads or fibers to transmit data. A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages modulated onto light waves.

Fiber optics has several advantages over traditional metal communications lines:

*   Fiber optic cables have a much greater bandwidth than metal cables. This means that they can carry more data.

*   Fiber optic cables are less susceptible than metal cables to interference.

*   Fiber optic cables are much thinner and lighter than metal wires.

*   Data can be transmitted digitally (the natural form for computer data) rather than analogically. 

The main disadvantage of fiber optics is that the cables are expensive to install. In addition, they are more fragile than wire and are difficult to splice.

Fiber optics is a particularly popular technology for local-area networks. In addition, telephone companies are steadily replacing traditional telephone lines with fiber optic cables. In the future, almost all communications will employ fiber optics.

Telephone Cable – This is a type of male connector used to connect a telephone to the telephone wiring in a home or office, and in turn to a local telephone network. It is inserted into its female counterpart, a telephone “jack” commonly fixed to a wall or baseboard. The standard for telephone plugs varies from country to country, though the RJ11 “modular connector” has become by far the most common. A connection standard such as “RJ11” specifies not only the physical connector but now it is wired (the “pin out”)

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