Computer network is a system consisting of computers and other network devices that work together to achieve a common goal. The purpose of the computer network are:

* Sharing of resources: for example, shared use of printers, CPUs, memory, hard drive
* Communication: eg electronic mail, instant messaging, chat
* Access to information: for example web browsing

In order to achieve the same goal, each part of the computer network and provide service request (service). Party requesting the service is called a client (client) and that provide services called the servant (the server). This architecture is called client-server systems, and is used in almost all computer network applications.

Classification Based on the scale:

* Personal Area Network (PAN)
* Campus Area Network (CAN)
* Local Area Network (LAN): a computer network that connects a computer to another computer with a limited distance.
* Metropolitant Area Network (MAN): principle the same as LAN, only the larger distance, ie 10-50 km.
* Wide Area Network (WAN): the distance between cities, countries, and continents. This is the same with the Internet.
* Global Area Network (GAN)

Based on the function: Basically every computer network is functioning as a client and server. But there is a network that has a dedicated computer as a server and the other as a client. There is also a computer that has no special function as a server only. Therefore, based on their function there are two types of computer networks:

* Client-server

Network is the computer with a dedicated computer as a server. A service / service can be provided by a computer or more. An example is a domain like www.detik.com lots served by the web server computer. Or it could be a lot of service / services provided by a single computer. Examples are jtk.polban.ac.id server that is a multi-service computer with the mail servers, web servers, file servers, database servers and others.

* Peer-to-peer

Namely computer networks where each host can be a server and also a client simultaneously. For example in the file sharing between computers on the Windows Network Neighborhood Network have 5 computers (we give the name of A, B, C, D and E) that provide access rights to the files they have. At one point A to access the file share of B named data_nilai.xls and also gives access to the file soal_uas.doc C. When accessing a file from B then A serves as a client and as a give file access to C then A serves as a server. Both functions were performed by the same A network like this is called peer to peer.

Based on network topology, computer networks can be divided into:

* Topology bus
* Topology stars
* Topology ring
* Mesh topology
* Topology tree
* Linear topology

Based on the criteria, the computer network can be divided into 4, namely:

1. Based on the distribution of sources of information / data

- This network centralized network consisting of Client and server computers which Client computer that serves as an intermediary to access sources of information / data derived from a single server computer

- Network is a combination of several distributed centralized network so that there are several computer servers that are interconnected with the Client to form a specific network system.


2. Based on geographic coverage can be divided into:

- Network LAN is a network that connects 2 computers or more in coverage such as laboratories, offices, and in 1 cafe.

- MAN network is a network that includes a big city and its local area. Examples of local telephone networks, cellular telephone systems, as well as some ISPs relay network Internet.

- Network WAN is a network with coverage throughout the world. PT network example. Telkom, PT. Indosat, as well as GSM networks such as Cellular Satelindo, Telkomsel, and much more.


3. Based on the roles and relationships of each computer in the data processing.

- Network Client-Server In this network there are 1 or more server computers and client computers. Computers will be computers or servers to client computers and altered through the protocol software on the network. Client computer as an intermediary to be able to access data on a server computer and the server computer to provide information needed by the client computer.

-Network Peer-to-peer in this network there are no client computer or server computer because all computers can make sending and receiving information so that all computers function as clients as well as a server.


4. Based on the data transmission media

- Wired Network (Wired Network) In this network, to connect one computer to another computer in the form of necessary liaison network cable. Function in the network cable to send information in the form of electrical signals between the network computer.

- Wireless Network (Wireless Network) is a network with the medium of electromagnetic waves. In this network does not need a cable to connect between computers that use electromagnetic waves to send signals between the computer information network.

souce:http://id.wikipedia.org/wiki/Jaringan_komputer
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Jakarta, March 2008 - Linksys ®, a division of Cisco, which is a leading provider of networking products and devices for home and small businesses, has launched the Wireless-G Home Router (WRH54G), the first wireless broadband router is customized for home users in Indonesia.

Full function router and an affordable price to help meet the needs of local users in Indonesia to build broadband wireless networks. In addition to the Linksys commitment to the Indonesian market, this product launch is also expected to further increase the penetration and use of broadband wireless networks by home users in Indonesia.

To reflect its uniqueness, WRH54G comes with a black design with dual-antenna is useful to support wireless performance to be optimized. With transmission speeds reaching 54Mbps and basic functions of the other, WRH54G offers some interesting features that prove the label as a Wireless-G broadband router is 'specially made for Indonesia' (Made for Indonesia).

Packed with features Friendly Controls of Internet Access, WRH54G provide support for access control capabilities that can be tailored to user preferences and needs (On-Demand) and the management of the desired time (Time-based). This capability is designed to help users monitor and control the use of broadband access at affordable prices, especially for those who use time-based services (Time-based) or volume (volume-based).
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Wireless-G Home Router WRH54G

WRH54G a Flexible Wireless Radio Control with On / Off function Control Scheduler to provide management capabilities for more than one scheduling system while protecting wireless access in the home. Users simply select the 'start / stop' existing or adjust the wireless signal strength on the device. This device is also equipped with build-in web-based setup wizard that helps users to install WRH54G easily and quickly.

As a wireless broadband network solutions integration, WRH54G also able to function as a Wireless Access Point, designed according to compatibility and standardization of devices Wireless-G (802.11g) and Wireless-B (802.11b) available today. Supported features 4-port full duplex 10/100 Ethernet switch, WRH54G network device capable of connecting an Ethernet cable, or even overlap with additional switches to provide more switch port connections. This product also supports encryption standard widely used in network industries, namely 128-bit encryption to protect data and user privacy. Users also facilitated in the security features enabled through the Linksys web-based utility, which is a web-based utility.


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Modem that comes from the word Modulator demodulator is a device used by phone lines to connect between two computers. Modem is in charge to change the digital signal from the computer into analog signals and vice versa so it can be accepted or sent through the phone wires.

In the majority of new generation mobile phones have built-in modem inside, so to access the Internet more easily done. In this article we will learn to use the phone's modem support, so the facility can be enabled modem in our computer. Cellular phones are used as an example here is the Nokia phone (Nokia 3105, 6225, 6585).

There are some basic steps that must be done in order to use this service:

* Phone with Computer Connection
* Installing the Modem Driver Nokia
* Create New internet connection


After doing these three steps correctly, then we are ready computers for browsing the Internet using a modem that is on the cellular phone. Actually, in principle, the above steps can be used for all mobile phone brands such as Siemens, Samsung, Sony Ericsson or other mobile phone brands have provided support modems.

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1. Understanding Computers

Here are some computer terms

1. Computers are a series of electronic machines or a group that consists of thousands and even millions of components that can cooperate with each other, and formed a working system neat and meticulous. This system can then be used to carry out a series of jobs automatically, based on the order of instructions or programs provided to him.

2. Computers are the result of the progress of electronics and informatics technology that serves as a tool for writing, drawing, editing pictures or photos, create animation, scientific analysis program operates, simulation and for control equipment.
3. Computers are a tool to ease the job supporting the human in the process of solving various problems, because these devices have the operational speed, the ability to save memory, reliable, and cost saving. source: TIK Class XI book published Widya Utama

2. Characterization Computers

Computers can be classified based on the processed data, computer skills, capacity and size, and the problem area.

2.1. Based on the data being processed, the computer classified into three, namely:

1. Analog computer

Is a type of computer that can be used to process qualitative data. The data is not a symbol, but still a state. Like for example: state of the air temperature or humidity, altitude or speed is a condition defined by the computer then that becomes a measure.
Analog widely used dipabrik-tujuannnya plant to control or produce a product. The definition is closer to analog computer with a robotic or automated machinery.

2. Digital computer

Is a type of computer that can be used to process data that is quantitatively (very many in number). Data from a digital computer is usually a symbol that has a specific meaning, for example: aphabetis symbols depicted with the letters A s / d Z, or as / dz, a numerical symbol represented by numbers 0 to 9, or special symbols, such as: ? / + * &!.

3. Hybrid computer

Is a type of computer that can be used to process data and quantitative or qualitative. Hybrid computer can also be said as a combination of analog and digital computers. This kind of computer system used by the various hospitals which used to examine the circumstances of the patient's body, which in turn, can release a variety of computer analysis presented in the form of images, graphics or text.

2.2. Based on ability, computers classified into three, namely:

1. Small scale computer

This kind of computer system has a capacity of 64 Mb to 8 Mb and can handle dozens of separate computer terminals of the computer center.

2. Medium scale computer

This kind of computer system has a capacity of between 512 Kb to 8 Mb and can handle hundreds of separate computer terminals of the computer center.

3. Large scale computer

This kind of computer system has a capacity of between 512 Kb to 8 Mb, but this computer has a higher speed.

2.3. Based on the capacity and size, computers are classified into three, namely:

1. Microcomputer (Personal Computer / PC)

At first, this kind of computer system created to meet the needs of the individual (personal). Individual needs in terms of storing or processing data, certainly not as much need for a company. Because of this, capabilities and technologies owned by the Personal Computer in the beginning was very limited.

With the benefits of relatively cheap price, small form-owned technology bet is already sufficient, then the personal computer became so popular so quickly. Personal computers are now not only used by individuals but in the end is widely used by companies to solve various problems diperusahaan.

a. Notebook / Laptop

Is the type of PC that can carry and can be used anywhere because it is equipped with a portable battery-power, so that without any electric-note-book can still be operated

b. PDA / Pocket Computer

Is a kind of pocket-sized PC that can be taken anywhere.

2. Midrange computer or mini computer

Mini computer has the capability of times greater when compared with the personal computer. This is caused by micro-pocessor used to process the data does have the ability far superior when compared with that used in micropocessor personal computers. Pisiknya size can for a small cupboard.
Mini computer in general can be used to serve more than one user (multi user). In this multiuser system, in the end personal computers are widely used as a terminal that serves to enter data. Example Minicomputer: IBM AS-400

3. Mainframe computer or mini computer

The main characteristic that distinguishes the notion of mini-computers to mainframes is, the mainframe has more than one processor. Thus, in terms of speed mainframe process much faster when compared with mini-computers.

Mainframe generally requires a special room where the environmental factors of temperature, humidity or smoke problems it can be monitored. This is because the value of the computer and the value of information stored in it is very expensive. The room is usually equipped with various electronic security systems.

4. Super Computer

As the name implies, the super computer has characteristics, namely high-speed process and have the ability to store data much larger when compared with the main-frame. The price is very large super computer and expensive. Satau One example is the super computer Cray-2. Super computer users are the countries that have developed or companies that are large, such as IPTN aircraft industry.
Due to the ability extraordinary and include the ability to read / tap various data from the satellite, then to purchase a super computer to get approval directly from the president. Indonesia has rejected a request by the American president when Nurtantio want to buy a super computer from the United

2.4. Based on the problem area, computers are classified into two, namely:

1. Special purpose computers

This kind of computer system can only solve one problem only, so only certain programs are intended in this computer. For example, computers used in oil refineries.

2. General-purpose computer

This kind of computer system can solve many problems. Computers are included in this type, ie digital and analog computers, but is commonly used digital computer. For example, computers and computer education for business. Canon PIXMA MX860 Wireless All-In-One office Printer


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