Network Model

The International Standards Organization (ISO) has defined a standard called the Open Systems Interconnection (OSI) reference model. This is a seven layer architecture listed below. Each layer is considered to be responsible for a different part of the communications. This concept was developed to accommodate changes in technology. The layers are arranged here from the lower levels starting with the physical (hardware) to the higher levels.

1. Physical Layer - The actual hardware. Concerned with the connection between the computer and the network.
2. Data Link Layer - Data transfer method (802x ethernet). Puts data in frames and ensures error free transmission. Also controls the timing of the network transmission. IEEE divided this layer into the two following sublayers.
   1. Media Access Control (MAC) - Used to coordinate the sending of data between computers. The 802.3, 4, 5, and 12 standards apply to this layer. If you hear someone talking about the MAC address of a network card, they are referring to the hardware address of the card.
   2. Logical Link control (LLC) - Maintains the Link between two computers by establishing Service Access Points (SAPs) which are a series of interface points. IEEE802.2.
3. Network Layer - IP network protocol. Routes messages using the best path available. Concerned with message priority, status, and data congestion.
4. Transport Layer - TCP, UDP. Provides properly sequenced and error free transmission. Recombines fragmented packets.
5. Session Layer - Determines when the session is begun or opened, how long it is used, and when it is closed. concerned with security and name recognition.
6. Presentation Layer - ASCII or EBCDEC data syntax. Makes the type of data transparent to the layers around it. Used to translate date to computer specific format such as byte ordering. It may include compression. It prepares the data, either for the network or the application depending on the direction it is going.
7. Application Layer - Provides the ability for user applications to interact with the network.

Many protocol stacks overlap the borders of the seven layer model. Transmission Control Protocol (TCP) provides the function of session and some of the transport layer. The Internet Protocol (IP) provides the function of the rest of the transport and most of the network layer. Netware Core Protocol (NCP) provides the function of the application, presentation, and the session layer.

About Data Entry

Data entry is the act of transcribing some form of data into another form, usually a computer program. Forms of data that people might transcribe include handwritten documents, information off spreadsheets from another computer program, sequences of numbers, letters and symbols that build a program, or simple data like names and addresses. Some people perform jobs that are exclusively data entry, while others, like programmers, might have to occasionally enter data.
Since the advent of computers, and since the beginning of typing, the need to collect and neatly present documents has required data entry. Good typists, especially those who are also excellent at 10-key typing often are the most qualified for data entry positions. On the other hand, many computer programmers are not terrific typists but still plow their way through inputting code into programs when needed

About Wide Area Network

Wide Area Networks (WANs) connect larger geographic areas, such as Florida, the United States, or the world. Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of network.
Using a WAN, schools in Florida can communicate with places like Tokyo in a matter of minutes, without paying enormous phone bills. A WAN is complicated. It uses multiplexers to connect local and metropolitan networks to global communications networks like the Internet. To users, however, a WAN will not appear to be much different than a LAN.

About Local Area Network

A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a writing lab, school, or building. Rarely are LAN computers more than a mile apart.
In a typical LAN configuration, one computer is designated as the file server. It stores all of the software that controls the network, as well as the software that can be shared by the computers attached to the network. Computers connected to the file server are called workstations. The workstations can be less powerful than the file server, and they may have additional software on their hard drives. On many LANs, cables are used to connect the network interface cards in each computer; other LANs may be wireless. See the Topology, Cabling, and Hardware sections of this tutorial for more information on the configuration of a LAN.

About Networking

Software is the technology revolution that at times brings surprising opportunities for us.  It’s help us economics growth, has successfully utilized such opportunities in the revolution to become an IT hotspot.

A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
The two basic types of networks include: 
1. Local Area Network ( LAN)
2. Wide Area Network ( WAN)

About Software

Software is the general term for information that's recorded onto some kind of medium. For example, when you go to the video store and rent or buy a tape or DVD, what you're really getting is the software that's stored on that tape or disk. Your VCR or DVD player are hardware devices that are capable of reading the software from a tape or disk and projecting it onto your TV screen, in the form of a movie.
Your computer is a hardware device that reads software too. Most of the software on your computer comes in the form of programs. A program consists of "instructions" that tell the computer what to do, how to behave. Just as there are thousands of albums you can buy on CD for your stereo, and thousands of movies you can buy to play on your VCR or DVD player, there are thousands of programs that you can buy to run on your computer.
When you buy a computer, you don't automatically get every program produced by every software company in the world. You usually get some programs. For example, when you buy a computer it will probably have an operating system (like Windows XP) already installed on it.
If you do purchase a specific program, it would be to perform some specific task. For example, you might use a graphics program to touch up photos, or you might use a word processing program to write text. You're using your Web browser program right now to read this text (assuming you're not reading a printed copy on paper). Just as there are umpteen different brands of toothpaste, there are umpteen different brands of word processing programs, graphics programs, and Web browsers.
For example, all graphics programs are designed to help you work with pictures. But there are many brands of graphics programs out there, including Adobe Photoshop, Jasc Paint Shop Pro. Adobe Illustrator, Arcsoft PhotoStudio, Corel Draw, ULead PhotoImpact, PrintShop Photo, and Macromedia Freehand, just to name a few. As to Web browsers, popular brands include Microsoft Internet Explorer, MSN Explorer, Netscape Navigator, America Online, and a few others.
When you purchase a program, you get the program stored on a CD as in the example shown at left. You may not have seen any boxes containing software when you bought your computer. That's because the software that came with your computer has been pre-installed onto your computer's hard disk for you. You don't need to use the CD to run a program that's already installed on your computer. You only need to keep the CDs as backups, in case something goes wrong with your hard disk and you need to re-install the programs.