Networks & Communications

In this post, we'll take a look at several common terms where networks are concerned.

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Node

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In a network, a node is a connection point that functions as a redistrubution point (to forward) or an end point (the destination) for data transmissions. A physical network node may be a data circuit-terminating equipment (DCE) that performs functions such as signal conversion and coding such as a modem. They may also be a data terminal equipment (DTE) that converts user information into signals or reconverts signals such as a printer. In a local area network (LAN) or the Internet, the nodes are ususally host computers.

A modem is an example of a physical node.
Source: http://www.computerwar.com.my/images/modem.jpg

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Client

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In computing, a client is an application or system that accesses a remove service on another computer system known as a server via a network. In the Internet, a web browser connecting to a service is a client. Similarly, instant messaging applications and online games are forms of clients that connect to a remote server.

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Server

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The HP MediaSmart Home Server.

Source: http://www.wired.com/images/productreviews/2009/01/pr_hp_mediasmart_server_350_f.jpg

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A server is a computer application that delivers a service, such as a web server delivering web pages requested by a browser or client. The data transmission between a client and a server is regulated by a protocol such as the Hyper Text Transfer Protocol (HTTP) between a web browser and a server.

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Hub

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A hub is a physical device in a wired network that connects Ethernet cables from several devices together, allowing each device to communicate with the others. Hubs are fairly simple devices requiring no manuals or configuration, but have largely been rendered obsolete because its functionality has been integrated into other devices such as routers or modems.

A Netgear hub.

Source: http://www.superwarehouse.com/images/products/netgear_ds108.jpg

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Network Interface Card (NIC)

A PCI network card.

Source: http://www.district-85.com/images/resource/devices/nic.jpg

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Network interface cards or network cards are a type of expansion card typically built for PCI slots to provide a system with the ability to connect to a network. Wireless network cards allow network connectivity wirelessly while Ethernet network cards allow a system to access a network via an Ethernet connection. Many modern motherboards usually provide an integrated network interface.

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Network Operating System (NOS)

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A network operating system is a type of OS designed to allow a computer to serve requests from other computers via its own components and programs for data and provides access to other resources and devices such as file systems and printers. Some standalone operating systems such as Mac OS X and every Windows OS since Windows 2000 contain NOS features. Examples of dedicated network operating systems include Cisco IOS and Windows NT.

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Distributed Processing

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'Distributed processing' refers to multiple computers on a network interacting with each other to achieve a common goal. Programs running on a distributed system are referred to as distributed programs. Distributed processing is commonly used in situations such as when data is produced at one location but is needed at another. Distributed processing may also involve distributing tasks to idle CPUs on the network so that the load on each CPU is smaller.

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Host Computer

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A host computer is a node on a network that can host information resources as well as application software for providing network services. Every host is a physical network node. Host computers are usually used by the network managers or administrators of the network.

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Network Manager

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A network manager or a network administrator is a person whose job is to maintain the computer hardware and software of a computer network, including managing network equipment. A network manager concentrates on the overall health of the network, server deployment, security, and manages the network connectivity within that network.

Input & Output

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Magnetic Ink Character Recognition (MICR)

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Magnetic Ink Character Recognition (abbreviated as MICR) is a technology involving the recognition of characters printed with a magnetic ink or toner, usually containing iron oxide (hence the magnetic properties of this technology). It is commonly used in the banking industry for the processing of cheques. A MICR machine first magnetises the characters before they are passed over the machine's read head, producing a unique waveform that is identified by the system.

A closer look at the characters detectable via MICR is shown in green on a cheque.
Source: http://doit.ort.org/course/input/images/287.gif

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Optical Character Recognition (OCR)
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A DILETTA TDR400 OCR machine.
Source: http://diletta.org/Graphic/TDR400%20OCR.jpg

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Optical Character Recognition (abbreviated as OCR) is the recognition of printed or written text characters by a computer, usually involving dedicated software by first photoscanning each character in the text, analysing the image and then translating it into character codes such as ASCII. It is used to digitally preserve library collections and has also been used to sort the mail.
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Optical Mark Recognition (OMR)
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Optical Mark Recognition or Optical Mark Reading (abbreviated as OMR) is the process of digitally recognising human-marked data from forms and test slips. Most conventional OMR machines use a dedicated scanner that emits a beam of light onto dedicated OMR forms. The difference in reflectivity at determined positions of the form is used to detect marked areas. One of the most familiar uses of OMR is on the answer sheets of examinations where candidates are required to use a specific grade of pencil.

An OMR answer sheet.
Source: http://iam0101.new21.net/zbxe/files/attach/images/1916/309/211/omr-form.jpg

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Dot Matrix Printer

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A dot matrix printer (also known as an impact matrix printer) is a computer printer that prints characters and illustrations with a printing head that moves back and forth in two directions along the printer by impacting pins against an ink ribbon to print closely spaced dots in the appropriate shape and formation. Dot matrix printers can print to multi-page forms and can print over a continuous sheet of paper instead of just multiple sheets of paper. However, dot matrix pritners are relatively noisy and tend to have limited printing quality.

A Panasonic dot matrix printer.

Source: http://img.alibaba.com/photo/104543319/Panasonic_Dot_Matrix_Printer_KX_P1121.jpg

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Plotters

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A plotter is a versatile vector graphics printing tool often confused with a printer, but uses line drawings instead of forming images with dots to print graphical plots. A common type of plotter is the pen plotter, which holds a drawing tool such as a pen or pencil with a mechanical arm to draw lines on paper. On the other hand, electrostatic plotters produce a raster image by charging paper with a high voltage which attracts the toner and melts it down into the paper with heat. They are comparatively fast, but are considered to be of inferior quality to pen plotters. Plotters may be connected to a computer or function independently. Plotters may be used to create layouts, diagrams and banners.

An electrostatic plotter.

Source: http://www.recycledgoods.com/zoom_s_p_12109_01.jpg.ashx

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Photo Printer

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A Canon photo printer.

Source: http://www.digitalworldtokyo.com/entryimages/251105_Canon_Printer.jpg

A photo printer is a type of printer (usually of the inkjet variety) used to print high quality digital photographs on specialised photo paper. Because of the need for high levels of detail, these printers usually have many nozzles and are able to print droplets as small as 1 picolitre. What commonly differentiates photo printer from conventional inkjet printers is the usage of additional specialised cartriges to increase the printer's colour range in order to produce more vivid and realistic images. It must be noted that a marketing ploy exists where conventional inkjet printers are marketed as photo printers because there are no official specifications of what makes an inkjet printer a photo printer.

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Portable Printer

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A Zink Polaroid PoGo Portable Printer

Source: http://gopaultech.com/files/2009/03/zink-polaroid-pogo-portable-printer.jpg

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A portable printer is, like its name implies, a printer designed for portability. They are usually compact and rely on an internal power source like a battery. This allows users to connect their digital cameras to the portable printer and supply it with paper to print their photographs on the spot without a computer.

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Fax Machine

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A Samsung fax machine.
Source: http://en.wikipedia.org/wiki/File:Samfax.jpg

A fax (short of fascimile) machine is used in telecommunications to transfer copies of documents over a telephone network. It consists of an image scanner, modem and a printer. A fax machine scans documents documents fed to it similar to the way scanners do to be sent digitally to the receiver and is able to print received documents. While most businesses currently retain some form of fax capability, they are increasingly becoming forgone for Internet-based systems.

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Multifunctional Devices

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A multifunctional device (also known as a Multi Function Product/Printer/Peripheral or an all-in-one) is a machine typically used in offices that possess the functionality of two or more devices, saving space that would otherwise be taken up by individual dedicated machines. A typical multifunctional device may have a combination of printer, scanner, photocopier, fax and e-mail capabilities.

A Canon IR2270 office multifunctional printer.

Source: http://en.wikipedia.org/wiki/Multifunction_printer

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Internet Telephone

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The term 'Internet telephone' typically refers to vocal communication over the Internet using the Voice over Internet Protocol (VoIP). This may include live calls or voice messages which are sent through the Internet as opposed to a public telephone network like conventional phones. This form of communication allows flexibility as more than one call may be transmitted simultaneously over a single connection. It also tends to have lower operational costs because of the way Internet services are billed compared to regular telephone calls. VoIP is commonly integrated with many Internet services such as instant messaging programs. However, dedicated VoIP phones also exist.

A Cisco VoIP phone.

Source: http://en.wikipedia.org/wiki/Internet_telephone

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Telephony

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'Telephony' refers to the general use of equipment to provide voice communication over distances by connection telephones together. Most modern telephones today are plugged into telephone jacks. 'Digital telephony' is the usage of digital technology in telephony. Almost all calls are provided this way, with the conversion between digital and analogue signals taking place inside the phone. IP telephony uses an Internet protocol to transmit voice data - essentially VoIP.