Dotman Computer Services

21/06/2013

What is Computer Virus?

A computer virus is an executable program. Depend on the nature of a virus, it may cause damage of your hard disk contents, and/or interfere normal operation of your computer.

By definition, a virus program is able to replicate itself. This means that the virus multiplies on a computer by making copies of itself. This replication is intentional; it is part of the virus program. In most cases, if a file that contains virus is executed or copied onto another computer, then that computer will also be "infected" by the same virus.

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. (Please refer to our web page on Handling Email's File Attachments for details.)

When a virus is introduced to a computer system, it can attach itself to, or sometimes even replace, an existing program. Thus, when the user runs the program in question, the virus is also executed. This usually happens without the user being aware of it.

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.
here are many types of computer viruses:

File virus : Most viruses fall into this category. A virus attaches itself to a file, usually a program file.

Boot sector virus : These viruses infect floppy and hard drives. The virus program will load first, before the operating system.

Macro Virus : This is a new type of virus that use an application's own macro programming feature to distribute themselves. Unlike other viruses, macro viruses do not infect programs; they infect documents.

18/06/2013

OA News

June 17, 2013
China can now boast the world’s fastest supercomputer, according to the semiannual TOP500 official listing of the world's fastest supercomputers released Monday.

Tianhe-2, or Milky Way-2, clocked in at number one with a performance of 33.86 petaflops per second, according to a press release issued byTOP500. The computer was developed by China’s National University of Defense Technology and will be deployed at the National Supercomputer Center in Guangzho, China, by the end of the year.

China last wore the crown of fastest supercomputer in November of 2010 with Tianhe-1.

The Chinese computer was a surprising winner, according to the release, because it was developed two years ahead of schedule.

Tianhe-2 has 16,000 nodes, each with two Intel Xeon IvyBridge processors and three Xeon Phi processors for a combined total of 3,120,000 computing cores.

"Most of the features of the system were developed in China, and they are only using Intel for the main compute part," said TOP500 editor Jack Dongarra in a news release accompanying the announcement. "That is, the interconnect, operating system, front-end processors and software are mainly Chinese," said Dongarra, who toured the Tianhe-2 development facility in May.

The previous number one, the Cray-made Titan computer installed at the U.S. Department of Energy’s (DOE) Oak Ridge National Laboratory in Tennessee, is now ranked second. The third ranking computer, IBM’s Sequoia, installed at DOE’s Lawrence Livermore National Laboratory is also in the U.S.

26/08/2011

A personal computer (PC) is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator. In contrast, the batch processing or time-sharing models allowed large expensive mainframe systems to be used by many people, usually at the same time. Large data processing systems require a full-time staff to operate efficiently.

26/08/2011