Communication and Network

Physical Connection

Twisted-pair cable(Telephone lines)

Twisted pair cable consists of two independently insulated wires twisted around one another. It is one of the cable type that used in telecommunication for very long time. Cable twisting helps to reduce noise pickup from outside sources and crosstalk on multi-pair cables. While twisted-pair cable is used by older telephone networks and is the least expensive type of local-area network cable, most networks contain some twisted-pair cabling at some point along the network.

Coaxial cable

A coaxial cable be composed of two conductors that share a common axis. It used to carry radio signals, video signals, measurement signals and data signals. Coaxial cable are typically characterized with the impedance and cable loss. Although it more expensive than standard telephone wire, it is much less susceptible to interference and can carry much more data.

Fiber-optic cable

Fiber optic cable is 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.
Optical fiber carries much more information than conventional copper wire and is in general not subject to electromagnetic interference and the need to retransmit signals. Now, most telephone company long-distance lines are made by optical fiber.

Computer Networks

Node

In a networks, node is a connection point, is either a redistribution point or a communication endpoint. In general, node has programmed or engineered capability to recognize and process or forward transmissions to other nodes.

Client

A client is an application or system that accesses a remote service on another computer system. Web browser is a client in its relationship with the computer that is getting and returning the requested HTML file.

Server

A server is a computer or device on a network that manages network resources. A network server is a computer designed to process requests and deliver data to other computers over a local network or the Internet, it is include Web servers, proxy servers, and FTP servers.

Hub

Hub is a common connection point for device in a network. In data communications, a hub is a place of convergence where data arrives from one or more directions and is forwarded out in one or more other directions. Hubs are commonly used to connect segments of a local area network.




Network Interface Card (NIC)

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



Network Operating System (NOS)

NOS is an operating system that includes special functions for connecting computers and devices into a local-area network. NOS is also designed for client computers and provide functions so the distinction between network operating systems and stand alone operating systems.



Host Computer

Host computer is a computer system that is accessed by user who are working at a remote location. Basically, this term is used when there are two computer systems connected by modems and telephone lines.

Network Manager

Network Manager is a set of co-operative tools that make networking simple and straightforward. Either wireless or wired, network manager allows you to quickly move from one network to another network.

Secondary Storage

Disk Caching

Disk cache is a mechanism for improving the time it takes to read from or write to a hard disk. Nowadays, the disk cache is usually included as part of the hard disk. A disk cache can also be a specified portion of random access memory (RAM). A portion of RAM used to speed up access to data on a disk.

Redundant Arrays of Inexpensive Disks(RAID)

RAID is a way of storing the same data in different places on multiple hard disks. It is also a 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. When data is placing on multiple disks, input and output operations can overlap in a balance way. Besides that, it also can improve performance.

File Compression and Decompression

Input and Output

Magnetic Ink Character Recognition(MIRC)

In computing, MIRC is a character recognition system that using special ink and character which can read and magnetised automatically. The banking industry use MICR to print details on cheques to enable automatic processing because MIRC uses magnetically chargeable ink or toner to print the numbers and special characters on the bottom of checks or other financial transaction documents and are therefore ideal for marking and identifying the account and sort code numbers on cheques.

Optical-Character Recognition(OCR)

Optical Character Recognition 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 translation of the character image into character codes, such as ASCII, commonly used in data processing. When a character is recognized, it will converted into an ASCII code. The libraries are using OCR to digitize and preserve their holdings. OCR is also used to process checks and credit card slips and sort the mail.

Optical-Mark Recognition(OMR)

Optical Mark Recognition also called Optical Mark Reading. It is a technology of electronically extracting intended data from marked fields, such as checkboxes and fill-in fields, on printed forms and it's also a process of capturing human-marked data from document forms such as surveys and tests. OMR technology scans a printed form, reads predefined positions and records where marks are made on the form.

Dot-matrix printer

Dot matrix printer also called impact matrix printer. It is a the type of computer printer that produces characters and illustrations by striking pins against an ink ribbon to print closely spaced dots in the appropriate shape, much like a typerwriter. Although dot-matrix printers are relatively expensive, it do not produce high-quality output. However it cannot produce high-quality output but it can print to multi-page forms that laser and ink-jet printers cannot do. Dot-matrix printers have two important characteristics that are speed and print quality.

Plotter

A device that draws pictures on paper based on commands from a computer. There are two types of main plotters, pen plotters and electrostatic plotters.Plotters are different from printers because they draw lines using a pen and they can produce continuous lines but printers can only simulate lines by printing a closely spaced series of dots. Multicolour plotters use different colour pens to draw different colours. Plotters are more expensive than printers because they are used in engineering application where precision is mandatory.

Photo Printer

Photo printer usually is a injek printer. It is a printer specialized for smaller prints such as 4x6" and 5x7". Photo printer is specifically designed to print high quality digital photos on photo paper and it usually have a very high number of nozzles and are capable of printing droplets as small as 1 picoliter.

Portable Printer

Portable printer is useful for people that are travelling but who need to work while on the go because is light weight and easy to carry.It just like with laptop computers and the smaller notebooks a reduction in size will more than like reduce the power and the features, while raising the price on the product.

Fax Machine

Fax machine is a telecomunication technology that can send or receive pictures and text over a telephone line. Fax machines work by digitizing an image,it dividing it into a grid of dots. In this way, the fax machine translates a picture into bit map that can be transmitted like computer data. A fax machine reads the incoming data and translates the bitmap into dots, and reprints the picture.

Multifunctional Device

A Multifunctional Device is an office machine which incorporates the functionality of multiple devices in one. It is also a single device that serves several functions. Typically, multifunctional device act as a printer, scanner, fax machine and also a photocopier. It become popular for SOHO user is because it more cheaper than
buying four separate devices.

Internet Telephones

Internet telephones are a category of hardware and software that enables people to use the Internet as a transmission medium for telephone calls. For people who have free or fixed-price Internet access, internet telephones software can provides free telephone calls anywhere in the world. Internet telephones do not have the same quality of telephone service as direct telephone connections.