Chapter 9

-Modulation

Modulation is a signal which gives the addition of information to an electronic signal carrier. The same as morse code which are invented for telegraphy and still used in radios .

-Demodulation

Demodulation is a electronics process by an output wave/signal is obtained having the aspect of the orginal modulating wave/signal. Demodulation process is basically the reverse process of modulation.

-Bandwidth

Bandwidth is a signal process which is passed through frequency or radio bandwidth by the range of frequencies . Bandwidths are normally counted by hertz . Bandwidth could also be the rate of data transfer . These bandwidths are counted by bit rate . 

-TCP/IP

Transmission Control Protocol/Internet Protocol(TCP/IP) is the language or protocol of the internet. The IP is the basic communications to private or public network . You may be able to send the file to another computer which has IP address through the internet.

-Node

Node is a connection point either a redistribution point or communication end point . The definition of node is not fix and it depends on the network and protocol layer. Its probably an active electronic device that is fixed to a network and have to ability to send , receive or forwarding informations through a communication channel.

-Client

Client is an application that is able to access a remote service on another computer system , which is also known as server . Clients that connect to the web server and also get web pages are known as Web browsers.

-Server

Server is a computer program which runs to serve the needs of other programs, also known as clients. Its a software/hardware system which is running on a dedicated computer such as a database server, file server, etc etc

-Network Operating Systems 

A network operating system(NOS) is a software that runs servers and also allows the server to do various functions . The functions such as managing datas, users , groups.security,applications and many more is applied. It also allowed sharing files and printer access among other computer in the network.

Secondary Storage

-Disk caching

 Disk caching is basically have the same function as the one in the computers. It improves the hark disk performance by anticipating the data. The hard disk remembers the number of usage of a certain files or program and keeps it in the cache so it can speed the information transfer.

-File compression

 This program can increase the total storage capcity by minimizing the amount of space taken to store certain datas.With compressed files , you can transfer files from one computer to another much more faster than the actual file.People normally send compressed files through the net.


-File decompression

After the file is compressed and sent through the net , the user needs to decompress the files in order to open what is in the folder. By decompressing means taking out the data and put it onto your desktop . This will takes up much more space than the compressed files.


-Internet hard drive

Internet hard drive is a place where you can store your storage and profiles online . These website must be paid in order the get the space on the internet. This can be much faster and more portable than a normal hard drive . However, the files on the internet hard drive are not safe and might be intruded

-Optical DIsc Drive

A optical disc drive is a disk drive from the desktop which uses laser light or electromagnetic waves that reads and writes data from the computer.These Optical disk drive can work on CD,DVD and Blu-Ray disc . Its often used to burn informations onto the disc.

-Solid-state storage

A solid state storage is a data storage device that is able to store persistent data. It uses micro chips to store the datas in the storage and it contains no moving parts

Input and output

-Ergonomic keyboard

 An ergonomic keyboard is a designed keyboard to reduce strain on the hand while typing . It usually have a V shape similar according to the humans right and left hands. The downfall of this keyboard is expensive , too bulky ,heavy and not easily portable.


-ink-jet printer

 Printers transfer processed information by the system unit and comes out as paper. The Ink jet printer sprays ink at high speed onto the paper to appear as words or images . This type of printer are the most common used because its reliable , quiet and inexpensive.


-laser printer

 Laser printers uses laser to beam to produce words and images similar to a photocopy machine. The resolution of these printers are high quality . Its more expensive than ink-jet printers but its much faster and are mostly used in offices.


-magnetic-ink character

 Magnetic ink character recognitions(MIRC) is a character recognition technology which are usually used by banks . The MIRC allows technologies to read printed information such as cheques account number. MIRC is different from barcodes because the MIRC can be read by humans too .


-optical-character recognition

 Optical character recognition(ORC) is a technology which is able to transfer hand written images to the computer. Most people use this technology to convert books into online files . On the other hand , people also use it to computerize record books , or to publish something online .


-optical-mark recognition

 Optical mark recognition(OMR) is a device that shines a beam of light onto a paper to leave some reflectivity on the paper. The paper is used to detect darker shades of colours because it blocks the reflection of light rather than the blank areas of the paper. This type of papers are mostly used for examinations