Router

A router is a device that forwards data packets between computer networks, creating an overlay internetwork. A router is connected to two or more data lines from different networks. When a data packet comes in on one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Routers perform the "traffic directing" functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it gets to its destination node.

Bridge

Bridging is a forwarding technique used in packet-switched computer networks. Unlike routing, bridging makes no assumptions about where in a network a particular address is located. Instead, it depends on flooding and examination of source addresses in received packet headers to locate unknown devices. Once a device has been located, its location is recorded in a table where the source address is stored so as to avoid the need for further flooding. The utility of bridging is limited by its dependence on flooding, and is thus only used in local area networks.

Switch

A network switch or switching hub is a computer networking device that connects network segments or network devices. The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer (layer 2) of the OSI model. Switches that additionally process data at the network layer (layer 3) and above are often referred to as layer-3 switches or multilayer switches.

Digital Divide

The Digital Divide refers to any inequalities between groups, broadly construed, in terms of access to, use of, or knowledge of information and communication technologies (ICT). The divide inside countries (such as the digital divide in the United States) can refer to inequalities between individuals, households, businesses, and geographic areas at different socioeconomic and other demographic levels, while the Global digital divide designates countries as the units of analysis and examines the divide between developing and developed countries on an international scale. The impact of the Digital Divide is massive, it affects every county around the world, the impact of the divide is daunting as a large amount of people have witnessed, not being able o access or use such technology can make a person become an outcast of society in today’s life, the impact on their lives is massive, so if any student who's country is well developed might find it hard to study in other countries due to digital divide.

Network Hardware

Networking hardware or networking equipment typically refers to devices facilitating the use of a computer network.Computer networking devices are units that mediate data in a computer network. Computer networking devices are also called network equipment, Intermediate Systems (IS) or InterWorking Unit (IWU). Units which are the last receiver or generate data are called hosts or data terminal equipment. Here's an example of some of the network hardware: 1-Router: a specialized network device that connects a LAN(local area network) with a WAN(wide area network). 2-Bridge: a device that connects 2 or more LANs together. 3-Switch: a device that connects a number of computers together to make a LAN, but the switch is a more ‘intelligent’ device than a hub: if it receives a message, it checks who it is addressed to, and only sends it to that specific computer.

Wikis

A wiki is a website whose users can add, modify, or delete its content via a web browser using a simplified markup language or a rich-text editor. Wikis are typically powered by wiki software and are often created collaboratively by multiple users. Examples include community websites, corporate intranets, knowledge management systems, and notetaking.

Blogs

A blog is a personal journal published on the World Wide Web consisting of discrete entries ("posts") typically displayed in reverse chronological order so the most recent post appears first. Blogs are usually the work of a single individual, occasionally of a small group, and often are themed on a single subject. Blog can also be used as a verb, meaning to maintain or add content to a blog.

Forums

An Internet forum, or message board, is an online discussion site where people can hold conversations in the form of posted messages. They differ from chat rooms in that messages are at least temporarily archived. Also, depending on the access level of a user or the forum set-up, a posted message might need to be approved by a moderator before it becomes visible. Forums have a specific set of jargon associated with them; e.g. a single conversation is called a "thread". A discussion forum is hierarchical or tree-like in structure: a forum can contain a number of subforums, each of which may have several topics. Within a forum's topic, each new discussion started is called a thread, and can be replied to by as many people as so wish

Expert Systems

What is an Expert System?

An expert system is computer software that attempts to act like a human expert on a particular subject area.

Expert systems are often used to advise non-experts in situations where a human expert in unavailable (for example it may be too expensive to employ a human expert, or it might be a difficult to reach location).

How Do Expert Systems Work?

An expert system is made up of three parts:
A user interface - This is the system that allows a non-expert user to query (question) the expert system, and to receive advice. T|bn\Uerface is designed to be a simple to use as possible.
A knowledge base - This is a collection of facts and rules. The knowledge base is created from information provided by human experts
An inference engine - This acts rather like a search engine, examining the knowledge base for information that matches the user's query.

Process Flow Diagram

A Process Flow Diagram - PFD - (or System Flow Diagram - SFD) shows the relationships between the major components in the system. PFD also tabulate process design values for the components in different operating modes, typical minimum, normal and maximum. A PFD does not show minor components, piping systems, piping ratings and designations.

A PFD should include:

Process Piping
Major equipment symbols, names and identification numbers
Control, valves and valves that affect operation of the system
Interconnection with other systems
Major bypass and recirculation lines
System ratings and operational values as minimum, normal and maximum flow, temperature and pressure
Composition of fluids

This figure depict a small and simplified PFD:

Data Flow Diagrams

A data flow diagram (DFD) is a graphical representation of the "flow" of data through an information system, modelling its process aspects. Often they are a preliminary step used to create an overview of the system which can later be elaborated.DFDs can also be used for the visualization of data processing (structured design).

A DFD shows what kinds of data will be input to and output from the system, where the data will come from and go to, and where the data will be stored. It does not show information about the timing of processes, or information about whether processes will operate in sequence or in parallel (which is shown on a flowchart).

System Flowchart

What is a System Fowchart?
System flowcharts are a way of displaying how data flows in a system and how decisions are made to control events.
To illustrate this, symbols are used. They are connected together to show what happens to data and where it goes. The basic ones include:

Symbols used in flow charts
Note that system flow charts are very similar to data flow charts. Data flow charts do not include decisions, they just show the path that data takes, where it is held, processed, and then output.

Flowchart

What is a Flowchart?

A flowchart is simply a diagram which shows the breakdown of a task or system into all of the necessary steps.

Each step is represented by a symbol and connecting lines show the step-by-step progression through the task.

Have a look at the diagram below. It shows the process of ordering a burger.

There is a clear start, a series of steps, a clear direction of flow and a clear end or finish point.

This is a very simple flowchart. For some tasks or systems, the flowchart can be very complex and detailed.

System Design

We have discussed before about the first stage of the system life cycle, which is the system analysis. And based on the user requirements and the detailed analysis of a new system, the new system must be designed. This is the phase of system designing. It is a most crucial phase in the development of a system. Normally, the design proceeds in two stages :

preliminary or general design
Structure or detailed design
Preliminary or general design: In the preliminary or general design, the features of the new system are specified. The costs of implementing these features and the benefits to be derived are estimated. If the project is still considered to be feasible, we move to the detailed design stage.

Structure or Detailed design: In the detailed design stage, computer oriented work begins in earnest. At this stage, the design of the system becomes more structured. Structure design is a blue print of a computer system solution to a given problem having the same components and inter-relationship among the same components as the original problem. Input, output and processing specifications are drawn up in detail. In the design stage, the programming language and the platform in which the new system will run are also decided.

There are several tools and techniques used for designing. These tools and techniques are:

1-Flowchart
2-Data flow diagram (DFDs)
3-Data dictionary
4-Structured English
5-Decision table
6-Decision tree

Benefits:
1-Improved system performance; individually tailored configuration advice demonstrates where improvement is necessary, and how to improve the system to regain lost performance.

2-Customers gain a detailed understanding of how their users use their system. This Usage Profile can be leveraged to develop future architecture changes.

3-Potential to learn of future concerns, allowing customers to take proactive measures to avoid problems.

4-A baseline performance level is established against which benefits can be compared and changes to the system predicted or foreseen.

System Analysis

System analysis is the process of examining an existing system in detail, in simple terms analysis is to see what data comes in to the company, how it is processed and and what outputs they produce.The purpose of analysing the system is to see how data flows around the system. In particular the process of system analysis requires:

1-Collecting information on how the existing system works.
2-Establishing its inputs, outputs and processing.
3-Recording information, for example in the form of data flow diagrams.
4-Identifying problems.

As we have mentioned the first stage of system analysis is collecting information,and there are four methods of doing this:

1-Examination of documents
Examining all the documents within a system for example, bills, invoices, letters, order forms, payslips etc.

2-Questionnaires
The most common way of gathering information. It is a printed sheet given to the employees, which contains questions for them to answer about the system. For example, what details of the worker and their pay would you like to see on your worker's payslips?

3-Interviews
Preparing an interview with an employee on certain date, to discuss them about the system. But most probably employees will give false information.

4-Observation
Observing and having a look on the how the employees work, but most employees won't feel comfortable with this, and others might give wrong impressions while being observed, and so the analyst will get wrong information.

Activity 12 Page 13

I recently visited Ebay, which of course you might know. Ebay's main purpose is creating an online market, where goods are sold and bought between the buyer and the seller. There is also auctions in Ebay, like for any product you place a bid to buy the product at a certain price then if another one is also interested in buying that product he places a higher bid and so on, until someone places a bid which no other will placer a higher one he'll get that product. Or you can buy the product immediately but in a much higher price.

SMS

Invitation normal form:
Hello everybody, there is a party next thursday in my house starting from 5.00.So i hope you all come.

Invitation SMS form:
Hi evrybody, theres a prty nxt thursday in my house strting frm 5. so ihope u all come.

BE A FOLLOWER!!

Feel free to be a follower, just click on the button Follow below!!

The Disadvantages Of Using E-mail

E-mails have many advantages as well as disadvantages unfortuately.Because emails are easy to use, so it is also easy to misuse. And misusing the email could be mostly in sending inappropriate messages to others, such as some spoof others addresses, they do that by using faking adresses, they could use the presidents address! Another type of misusing email are by sending viruses, worms and trojans, which harm your computer. So simply becareful in using your emails.