Assalamualaikum.....i back!!!=) now i want to revision about important topic, and i thing this topic is very usefull for u=)

Title : Computer security and safety, ethisc and privacy

Computer security is a branch of computer technology known as information security as applied to computer and network.Every computer must be a security so that computer can not entered by virus.
Another point is cybercrime. Cybercrime is an online or Internet-based illegal act such as ,

• Hacker
• Cracker
• Script Kiddies
• Corporate Spies
• Unethical Employees
• Cyberextortionists
• Cyberterroirists

An infected computer has one or more of the following symptoms :

• Operating system runs much slower than usual
• Available memory  is less than expected
• Files become corrupted
• Screen displays unusual message or image
• Music or  unusual sound plays randomly
• Existing programs and files disappear
• Program or files do not work properly
• System properties change
• Operating system does not start up
• Operating system shuts down unexpectedly

 A backup is a duplicate of a file , program , or disk that can be used if the original is lost , damaged  or destroyed to back up a file means to make a copy of it.
Have a to type of backup :

• Full backup
• selective backup

Wireless is a refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications netwocrk and enterprise (business) installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. Wireless telecommunicatios networks are generally implemented and administered using a transmission system called radio waves. This implementation takes place at the physical level (layer) of the OSI model network structure.

Topologies



What is topologies ???

Topology from the Greek is mean place and study,this  is a major area of mathematics concerned with properties that are preserved under continuous deformations of objects, such as deformations that involve stretching, but no tearing or gluing. It emerged through the development of concepts from geometry and set theory, such as space, dimension, and transformation.
Topology includes many subfields. The most basic and traditional division within topology is point-set topology, which establishes the foundational aspects of topology and investigates concepts inherent to topological spaces for basic examples include compactness and connectedness is algebraic topology, which generally tries to measure degrees of connectivity using algebraic constructs such as homotopy groups and homology; and geometric topology, which primarily studies manifolds and their embeddings (placements) in other manifolds. Some of the most active areas, such as low dimensional topology and graph theory, do not fit neatly in this division.

What is network topologies ???

Network topology is the layout pattern of interconnections of the various elements links and  nodes of a computer or biological network. Network topologies may be physical or logical. Physical topology refers to the physical design of a network including the devices, location and cable installation. Logical topology refers to how data is actually transferred in a network as opposed to its physical design. In general physical topology relates to a core network whereas logical topology relates to basic network.

A local area network (LAN) is one example of a network that exhibits both a physical topology and a logical topology. Any given node in the LAN has one or more links to one or more nodes in the network and the mapping of these links and nodes in a graph results in a geometric shape that may be used to describe the physical topology of the network. Likewise, the mapping of the data flow between the nodes in the network determines the logical topology of the network. The physical and logical topologies may or may not be identical in any particular network.

The type of network of topologies :

But I want to introduce just three network topologies such as ring topology, bus topology and star topology.

Ø  Ring Topology 

Ring topology is a ring network in the network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring. Data travels from node to node, with each node along the way handling every packet.

Advantages

•   Data is quickly transferred without a ‘bottle neck’. (very fast, all data traffic is in the same direction.
• The transmission of data is relatively simple as packets travel in one direction only.
• Adding additional nodes has very little impact on bandwidth
• It prevents network collisions because of the media access method or architecture required.

Disadvantages

•  Data packets must pass through every computer between the sender and recipient therefore this makes it slower.
•  If any of the nodes fail then the ring is broken and data cannot be transmitted successfully.
• It is difficult to troubleshoot the ring.
• Because all stations are wired together, to add a station you must shut down the network temporarily.
• In order for all computers to communicate with each other, all computers must be turned on.

·    

Ø  Bus Network

A bus network topology is a network architecture in which a set of clients are connected via a shared communications line, called a bus. There are several common instances of the bus architecture, including one in the motherboard of most computers, and those in some versions of Ethernet networks.

 Advantages

•   Easy to implement and extend
• Well suited for temporary networks (quick setup)
• Initially less expensive than other topologies

·       

Disadvantages

•  Difficult to administer/troubleshoot.
• Limited cable length and number of stations.
• If there is a problem with the cable, the entire network goes down.
• Maintenance costs may be higher in the long run.
•  Performance degrades as additional computers are added or on heavy traffic.
• Low security (all computers on the bus can see all data transmissions).
• One virus in the network will affect all of them (but not as badly as a star or ring network).
• Proper termination is required.(loop must be in closed path).
• If one node fails, the whole network will shut down.
•  If many computers are attached, the amount of data flowing causes the network to slow down.

Ø  Star Network

Star network  are fairly easy to install and maintain. Nodes can be added to and removed from network with little or no disruption the nertwork.  

Advantages

•   Good performance
• easy to set up and to expand. Any non-centralised failure will have very little effect on the network, whereas on a ring network it would all fail with one fault

Disadvantages

•  Expensive to install
• Extra hardware required

Assalamualaiakum and salam 1Malaysiaa ^___^

Now i would like to discuss about virus in your computer and what is latest antivirus marked.

Title : virus and antivirus

What is virus??

  

   A computer virus is a program that spreads by first infecting files or the system areas of a computer or network router's hard drive and then making copies of itself. Some viruses are harmless, others may damage data files, and some may destroy files. Viruses used to be spread when people shared floppy disks and other portable media, now viruses are primarily spread through email messages.

Viruses can also replicate themselves. All computer viruses are man-made. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.

A virus can be introduced to a computer system along with any software program. For Internet users, this threat can come from downloading files through FTP (file transfer protocol), or referencing email attachments.

A virus program contains instructions to initiate some sort of "event" that affects the infected computer. Each virus has an unique event associated with it. These events and their effects can range from harmless to devastating. For examples:

· An annoying message appearing on the computer screen.

· Reduced memory or disk space.

· Modification of data.

· Files overwritten or damaged.

· Hard drive erased.

List latest virus in market.

·         Kaspersky Antivirus

·         Avira antivirus

·         Avast antivirus

·         Microsoft security essential

·         AVG antivirus

But, better to use Kaspersky Antivirus because more function to protect your computer from virus.The benefit is

• Real-time protection against viruses and spyware
• Scanning of websites and emails for malicious code
• Protection for your digital identity at all times
• Vulnerability scan and treatment advice
• Easy-access Desktop gadget

 

 So use any types antivirus and can make safety your computer.....//=)
that all....

asslamualaikum....hye  guys..i thing has long time i not up load my suggestion or knowlegde,or little information to you know.....^_____^
now i would like you  know about input and output about computer...

WHAT IS INPUT????

Input is any hardwere device that sends data to the computer, without any input devices, a computer would only be a display device and not allow users to interact with it, much like a TV. For example like your computer such as mouse,web cam, keyboard and other thing information to put your computer.Like some TV if do you  use without remote control you cannot exchange your channel, so remote control like same as input device.More defination input is allow to enter data and instruction into a computer.

images for input :

     

keyboard

mouse



microphone



WHAT IS OUTPUT????

An output device receives information from the computer and translates it from machine language to a form that humans can read or so that another machine can read the information. An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) to the outside world.
Electronic output devices can be mechanical, audio, or visual. Mechanical outputs include motors, solenoids, and other electromagnetic devices. Audio outputs include buzzers, loudspeakers, piezo transducers, and ultrasonic transmitters. Mechanical and audio outputs tend to have a higher power demand than other output devices. Visual outputs include lamps, LEDs (light-emitting diodes), and infrared transmitters.To more better  understand is output means hardware component tahat conveys information to one or mare people.
Such as printer is also output to print out your assigment and other thing. Besides printer, monitor,mechine photostes or other related to output.

show images output :

             
Printer




speaker

Now you can know a bit about input and output.This information is also what i know and from my study my learning in my class.




so good luck for your reading and not to be sleeping......\\=)

general knowledge  =)

Advantages and Disadvantages of the Internet 

Today,  Internet has brought a globe in a single room. Right from getting news across the corner of the world to accessing knowledge resources to shopping, everything is at your fingertips. Internet has tremendous potential and a lot to offer in terms of services.




 


 










 more information can't give from internet. 

The advantage is :

1) Faster Communication  - the mean its Internet has always been speedy communication and it has excelled way beyond the expectations. Now, you can communicate in a fraction of second with a person who is sitting in the other part of the world. wherever you go you can seacrh internet or chatting with your friends and explore what do you want and what do you know.

2) Information Resources  - Information is probably the biggest advantage that Internet offers. Internet is a virtual treasure trove of information. The search engines like Google, Yahoo are at your service on the Internet. There is a huge amount of information available on the Internet for just about every subject known to man, ranging from government law and services, trade fairs and conferences, market information, new ideas and technical support, the list is simply endless.

4) Entertainment - Entertainment is another popular raison d'être why many people prefer to surf the Internet. Downloading games or just surfing the celebrity websites are some of the uses people have discovered. Even celebrities are using Internet effectively for promotional campaigns.

5) Social Networking - One cannot imagine an online life without Facebook or Twitter. Social networking has become so popular amongst youth that it might one day replace physical networking. It has evolved as a great medium to connect with millions of people with similar interests. Apart from finding long-lost friends, you can also look for job, business opportunities on forums, communities etc. Besides, there are chat rooms where users can meet new and interesting people. Some of them may even end up finding their life partners.

The disadvantage is : 

1) Virus Threat - Internet users are often plagued by virus attacks on their systems. Virus programs are inconspicuous and may get activated if you click a seemingly harmless link. Computers connected to Internet are very prone to targeted virus attacks and may end up crashing.

2) Social Disconnect -Thanks to Internet, people now only meet on social networks. More and more people are getting engulfed in virtual world and drifting apart from their friends and family. Even children prefer to play online games rather than going out and mingling with other kids. This may hamper a healthy social development in children.

3) Theft of Personal Information - If you use the Internet for online banking, social networking or other services, you may risk a theft to your personal information such as name, address, credit card number etc. Unscrupulous people can access this information through unsecured connections or by planting software and then use your personal details for their benefit. Needless to say, this may land you in serious trouble.