Communication and Network

Physical Connection
Twisted-Pair

Twisted pair is the ordinary copper wire that connects home and many business computers to the telephone company. To reduce crosstalk or electromagnetic induction between pairs of wires, two insulated

copper wires are twisted around each other. Each connection on twisted pair requires both wires. Since some telephone sets or desktop locations require multiple connections, twisted pair is sometimes installed in two or more pairs, all within a single cable.

Coaxial Cable

Coaxial cable is the kind of copper cable used by cable TV companies between the community antenna and user homes and businesses. Coaxial cable is sometimes used by telephone companies from their central office to the telephone poles near users.




Fiber-Optic Cable

A technology that uses glass (or plastic) threads (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.

Network Terms

Node

In a network, a node is a connection point, either a redistribution point or an end point for data transmissions. In general, a node has programmed or engineered capability to recognize and process or forward transmissions to other nodes.

Client

A client is the requesting program or user in a client/ server relationship. For example, the user of a Web browser is effectively making

client requests for pages from servers all over the Web. The browser itself is a client in its

relationship with the computer that is getting and returning the requested HTML file. The computer handling the request and sending back the HTML file is a server.

Server

In information technology, a server is a computer program that provides services to other computer

programs (and their users) in the same or other computers. The computer

that a server program runs in is also frequently referred to as a server (though it may be used for other purposes as well).

Hub

A common connection point for devices in a network. Hubs are commonly used to connect segments

of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

Network Interface Card ( NIC)

Often abbreviated as NIC, an expansion board you insert into a computer so the computer can be connected to a network. Most NICs are designed for a particular type of network, protocol, and media, although some can serve multiple networks.

Network Operating System (NOS)

A network operating system (NOS) is a computer operating system system that is designed primarily to support workstation, personal computer, and, in some instances, older terminal that are connected on a local area network (LAN) Artisoft's LANtastic, Banyan VINES, Novell's Netware, and Microsoft's LAN Manager are examples of network operating systems. In addition, some multi-purpose operating systems, such as Windows NT and digital's openVMS come with capabilities that enable them to be described as a network operating system.

Host Computer

In computer networking, a network host, Internet host, host, or Internet node is a computer connected to the Internet - or more generically - to any type of data network. A network host can host information resources as well as application software for providing network services.

Network Manager

NetworkManager is a software utility aimed at simplifying the use of computer network on Linux and other Unix-Like operating systems.The project was initiated in 2004 by Red-Hat, with the goal of enabling Linux users to more easily deal with modern networking needs, particularly wireless networking. NetworkManager takes an opportunistic approach to network selection, attempting to use the best available connection as outages occur, or the user roams between wireless network. Ethernet connections are preferred over “known” wireless networks, which are preferred over wireless networks with SSIDs to which the user has never connected. The user is prompted for WEP or WPA keys as needed.

Secondary Storage

Performance Enhancement

Three ways to improve the performance of hand disks are:

Disk caching

A portion of RAM used to speed up access to data on a disk. The RAM can be part of the disk drive itself (sometimes called a hard disk (cache or buffer) or it can be general-purpose RAM in the computer that is reserved for use by the disk drive (sometimes called a soft disk cache). Hard disk caches are more effective, but they are also much more expensive, and therefore smaller. Nearly all modern disk drives include a small amount of internal cache.

Redundant arrays of inexpensive disks (RAID)

technology that allowed computer users to achieve high levels of storage reliability from low-cost and less reliable PC-class disk-drive components, via the technique of arranging the devices into arrays for redundancy.

File compression and decompression
The file compression and decompression take an existing file or files and produce a file or files that are compressed versions of the originals. The compression is also lossless, but the compression is not transparent to applications. An application can only operate on such files with the assistance of a file compression library. In addition, the only operations you can perform on such files are creating a compressed file from an original and recovering the original data from the decompressed version. Editing is typically not supported, and seeking is limited if supported at all.

Input and Output

Magnetic Ink Character Recognition (MIRC) is a character recognition technology that printed in a special typefaces with a magnetic ink or toner and used primarily by banking industry to facilitate the processing of cheque.The technology allows computers to read information (such as account numbers) off of printed documents. Unlike barcodes, however, MICR codes can be easily read by humans.

Optical-Character Recognition (OCR) is the recognition of printed or written text characters by a computer. This involves photoscanning of the text character-by-character, analysis of the scanned-in image, and then translation of the character image into character codes, such as ASCII, commonly used in data processing.





Optical Mark Recognition (OMR) also called Optical Mark Reading and OMR is the process of capturing human-marked data from document forms such as surveys and tests. In computing, a technique that enables marks made in predetermined positions on computer-input forms to be detected optically and input to a computer. An optical mark reader shines a light beam onto the input document and is able to detect the marks because less light is reflected back from them than from the paler, unmarked paper.




Dot- Matrix Printer is a type of printer that produces characters and illustrations by striking pins against an ink ribbon to print closely spaced dots in the appropriate shape. Dot-matrix printers are relatively expensive and do not produce high-quality output. However, they can print to multi-page forms (that is, carbon copies), something laser and ink-jet printers cannot do.


Plotter is a a device that draws pictures on paper based on commands from a computer. Plotters differ from printers in that they draw lines using a pen. As a result, they can produce continuous lines, whereas printers can only simulate lines by printing a closely spaced series of dots. Multicolor plotters use different-colored pens to draw different colors.





Photo Printer a photo printer is a printer (usually an inkjet printer) that is specifically designed to print high quality digital photos on photo paper. These printers usually have a very high number of nozzles and are capable of printing droplets as small as 1 picoliter.




Fax Machine is a short for facsimile machine, a device that can send or receive pictures and text over a telephone line. Fax machines work by digitizing an image, dividing it into a grid of dots. Each dot is either on or off, depending on whether it is black or white. Electronically, each dot is represented by a bit that has a value of either 0 (off) or 1 (on).




Multifunctional devices bring the worlds of copying, printing, finishing, and scanning together, all in one neat, efficient and cost-effective package. Highly efficient black-only multifunctional devices as well as a huge range of colour multifunctional devices to meet your particular requirements.




Internet telephone is a category of hardware and software that enables people to use the Internet as the transmission medium for telephone calls. For users who have free, or fixed-price Internet access, Internet telephony software essentially provides free telephone calls anywhere in the world. To date, however, Internet telephones does not offer the same quality of telephone service as direct telephone connections.