Types of Operating Systems

           Operating system can be broadly classified into two categories based on the type of interface provided to the user. Command Line Interface          In these types of operating systems the user can enter commands through the keyboard and each command will perform a specific action. But this type of interface is very difficult for a beginner to use, because the commands have to be remembered.           MS-DOS is such a Operating System. Dos stands for Disk Operating system. It was developed by Microsoft as an operating system in the 1980s. Windows 3x needed DOS to run, but the later versions...

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Operating System

         An Operating System or OS is a software program that enables the computer hardware to communicate and operate with the computer software. Without an Operating System, a computer would be useless. Features Expected of an Operating System To Startup and Shutdown the computer.  To act as an interface between the user and the hardware. To perform house keeping tasks such as file handling, disk/ memory management. To be able to allow the user to configure the system. This includes changing the types of printers, adding new hardware (such as sound cards), etc. ...

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The Internet

   The Internet is a network of autonomous computer networks that spans the globe. It provides an infrastructure for global electronic information exchange. Today the Internet is used by millions of people of facilitate various activities such as business, education and plain communication.    The Internet grew out of a United States Department of Defense project, the ARPANET (Advanced Research Project Agency Network) started in late 1960s. Its main objective was to provide network links between universities, research organizations and remote computer centers.             The following figure shows how the Internet is structured. At the bottom level are the...

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How to Protect a Computer from Computer Viruses

        There are many ways of preventing a computer from virus attack. Some of these precautions are listed below. Verbal Warning Avoiding the use of unchecked disks Avoiding the use of unauthorized or unchecked software Anti-virus Software         Anti-virus software contains anti-virus scanners, which look for viruses. On-access scanners - Automatically check the hard disk and diskette each time the system starts up. On-demand scanners - Executes only on users demand and can be scheduled to run at various times        Most commercial anti-virus software provides both types of scanners. It will take some time for an anti-virus software designer get to know about a new type of...

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Main Types of Virus

Boot Virus           Boot virus infects the boot sector of the hard disk and is activated every time the computer is switched on. Once infected, the computer may fail to start properly. Usually boot viruses spread from the boot sectors in floppy diskettes to the boot sector of the hard disk. When you start up the system with an infected diskette in the diskette drive, the virus transfers from the diskette to the boot sector of the hard disk. Once infected, the virus may remain in the main memory and infect other diskettes. File Virus (Parasitic Virus)          File viruses are virus programs attached to executable files. They become active every time the program is executed. Macro Virus         ...

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Main Phases of Virus Activity

The main phases of virus generally follows are; Gains access to the system Lies dormant Propagates Virus is triggered by some event Virus Action ...

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Popular Viruses and Worm Programmes

2000            May : The VBS/Loveletter ('ILOVEYOU') worm appeard. As of 2004 this is the most costly virus to business, causing upwards of 10 billion dollars in damage.   2001             January : A worm strikingly similar to the Morris worm, names the Ramen worm infected only Red Hat Linux machines running version 6.2 and 7.                July 13 : The Code Red worm attacking Microsoft Internet Information Services.                October 26 : The Klez worm is first identified.    2003              January 24 : The SQL slammer worm also known as the Sapphire...

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Components of a Virus

A virus comprises of four general components. The replicator (or Engine) : Replicates the virus. The safeguard : Prevents the detection and the removal of the virus. The trigger monitor : Monitors for a specific condition to deliver payload. These specific conditions may be the arrival of a particular date, time, keyboard stroke, etc. The payload : the action it does apart from propagation. This action may be an amusing or malicious action resulting in distraction from the current work or destruction of data....

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